Draft Airplane Greenhouse Gets Standards
Technical Support Document (TSD)
&EPA
United States
Environmental Promotion
Agency

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Draft Airplane Greenhouse Gas Standards
Technical Support Document (TSD)
Assessment and Standards Division
Office of Transportation and Air Quality
U.S. Environmental Protection Agency
NOTICE
This technical report does not necessarily represent final EPA decisions or
positions. It is intended to present technical analysis of issues using data
that are currently available. The purpose in the release of such reports is to
facilitate the exchange of technical information and to inform the public of
technical developments.
x=/EPA
United States
Environmttntsl ProlGfiliOn
Ag en cy
EPA-420-D-20-004
July 2020

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TABLE OF CONTENTS
Chapter 1 Industry Characterization	2
1.1	Introduction	2
1.2	Market Basics	5
1.3	Product Categories	6
1.4	Product Manufacturers	9
Chapter 2 Technology and Cost	14
2.1	Overview	15
2.2	Technology Principles	16
2.3	Technologies	32
2.4	Technology Application	38
2.5	Estimated Costs	41
2.6	Airplane Fuel Savings	52
2.7	Fuel Prices	56
2.8	Summary of Benefits and Costs	56
Chapter 3 Test Procedures	72
3.1	CAEP Test Procedure Requirements-Overview	72
3.2	Test Procedures for Airplane GHG Emissions Based on the Consumption of Fuel.... 72
3.3	Determination of the Fuel Efficiency Metric Value	73
3.4	Application of Rules for New Version of an Existing GHG-Certificated Airplane	75
3.5	Changes for non-GHG Certificated Airplane Types	78
Chapter 4 Airplane Performance Model and Analysis	81
4.1	Purpose and Scope	81
4.2	Methodology of the EPA Emissions Inventory and Stringency Analysis	81
4.3	Fleet Evolution Model and Data Sources	83
4.4	Full Flight Simulation with PIANO and Unit Flight Matrix	89
4.5	Inventory Modeling and Stringency Analysis	90
Chapter 5 Impacts on Emissions and Fuel Burn	95
5.1	Executive Summary	95
5.2	Introduction	95
5.3	Fleet Evolution Results and Baseline Emissions	96
5.4	Stringency Analysis of U.S. and Global CO2 Emission Impacts	106
5.5	Sensitivity Case Studies	108
Chapter 6 Analysis of Alternatives	121
6.1	Overview	121
6.2	GHG Emission Reductions and Costs of Two Alternative Scenarios	132
6.3	Sensitivity Case Studies	144
6.4	Summary	146
Chapter 7 Regulatory Flexibility Analysis	158
7.1	Requirements of the Regulatory Flexibility Act	158
7.2	Need for the Rulemaking and Rulemaking Objectives	159
7.3	Definition and Description of Small Entities	159
7.4	Summary of Small Entities to Which the Rulemaking Will Apply	159
7.5	Related Federal Rules	160
7.6	Projected Reporting, Recordkeeping, and Other Compliance Requirements	160
7.7	Projected Effects of the Proposed Rulemaking on Small Entities	160
7.8	Regulatory Alternatives to Accommodate Small Entities	160

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List of Acronyms
AC
Aircraft
AIR
Aerospace Information Report
ANPR
Advanced Notice of Proposed Rulemaking
APU
Auxiliary Power Unit
ASK
Available Seat Kilometers
ASTM
American Society for Testing and Materials
ATK
Available Ton Kilometers
AVL
Asset Value Loss
BAU
Business As Usual
BGA
Business and General Aviation Airplane
BPR
Bypass Ratio
CAA
Clean Air Act
CAEP
Committee on Aviation Environmental Protection
CAT
Airplane Category
CBI
Confidential Business Information
CFR
Code of Federal Regulations
CI
Continuous Improvement
CMS
Continuous Modification Status
ch4
Methane
C02
Carbon Dioxide
COzDB
C02 Certification Database
COD
Common Operations Database
DICE
Dynamic Integrated Climate and Economy model
DOC
Direct Operating Cost
DOT
Department of Transportation
ECS
Environmental Control System
EIA
Energy Information Administration
EIS
Entry Into Service
EP
Extended Production
EPA
Environmental Protection Agency
FAA
Federal Aviation Administration
FUND
Climate Framework for Uncertainty, Negotiation, and Distribution model
G&R
Growth and Replacement
GDP
Gross Domestic Product
GHG
Greenhouse Gas
HLFC
Hybrid Laminar Flow Control
1AM
Integrated Assessment Model

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ICAO
International Civil Aviation Organization
ICF
ICF International, Inc.
InP
In-production
IWG
Interagency Working Group
M
Millions
MTOM
Maximum Takeoff Mass
MTOW
Maximum Takeoff Weight
NG
Next Generation
NHTSA
National Highway Traffic Safety Administration
NLF
Natural Laminar Flow
NRC
Non-recurring Cost
NT
New Type Designs
N20
Nitrous Oxide
OD
Origin-Destination
OMB
Office of Management and Budget
PAGE
Policy Analysis of the Greenhouse Gas Effect model
PIANO
Project Interactive Analysis and Optimization
PIP
Performance Improvement Package
R&D
Research and Development
RC
Retirement Curve
RFA
Regulatory Flexibility Act
RGF
Reference Geometric Factor
RIA
Regulatory Impact Analysis
RPM
Revenue Passenger Miles
RTM
Revenue Ton Miles
SAE
Society of Automotive Engineers
SAR
Specific Air Range
SBA
Small Business Administration
SBFA
Small Business Flexibility Analysis
SBREFA
Small Business Regulatory Enforcement Fairness Act
SC
Survival Curve
SOs
Stringency Options
TAF
Terminal Area Forecast
TC
Type Certificate
TRL
Technology Readiness Level
TSD
Technical Support Document
TSFC
Thrust Specific Fuel Consumption

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Executive Summary
The Environmental Protection Agency (EPA) is proposing greenhouse gas (GHG) emission
standards and other requirements applicable to greenhouse gas emissions from certain classes of
engines used by certain civil subsonic jet airplanes (those with a maximum takeoff mass greater
than 5,700 kilograms), as well as larger subsonic propeller-driven airplanes (those powered by
turboprop engines with a maximum takeoff mass greater than 8,618 kilograms). These proposed
standards are equivalent to the Airplane CO2 Emission Standards adopted by the International
Civil Aviation Organization (ICAO) in 2017 and would apply to both new type designs (new
type design airplanes) and in-production airplanes, consistent with U.S. efforts to secure the
highest practicable degree of uniformity in aviation regulations and standards. The proposed
standards would also meet the EPA's obligation under section 231 of the Clean Air Act (CAA) to
adopt GHG standards as a result of the 2016 positive endangerment and contribution findings for
six well-mixed GHGs emitted by certain classes of airplane engines.
We project no reductions in fuel consumption and GHG emissions associated with the
proposed standards. This is because all the potentially affected airplanes currently in production
either meet the stringency levels of the proposed standards or will be out of production when the
proposed standards would take effect, according to our projected technology responses.
This Draft Technical Support Document (TSD) is generally organized to provide overall
background information, methodologies, and data inputs, followed by results of the various
technical and economic analyses. A summary of each chapter of the Draft TSD follows.
Chapter 1: Industry Characterization. In order to assess the impacts of the proposed GHG
standards upon the affected industries, and especially on any small entities, it is important to
understand the nature of the industries potentially impacted by the proposed regulations.
Further, it is helpful to put the contribution of the potentially impacted industry in context
regarding its contribution to the overall mobile source GHG inventories. This chapter provides a
general overview of the airplane and airplane engine industries, including some basic
information on the companies involved in them. It also provides brief overviews of current and
projected future air traffic, as well as the relative contribution of this market to overall mobile
source GHG emissions.
Chapter 2: Technology and Cost. This chapter presents details of the airplane and airplane
engine technologies and technology packages for reducing airplane GHG emissions and fuel
burn. The methodologies used for projecting technology usage and resultant improvements in
GHG/fuel burn are presented for both the near/mid-term and the long term. Specific airplane and
engine technologies and their associated fuel burn improvements are then discussed, followed by
the projected costs of these technologies. This information provides the basis for the emissions
and cost projections.
Chapter 3: Test Procedures. This chapter describes the relevant test procedures, including
methodologies for determining GHG emissions based on fuel consumption and the determination
of the fuel efficiency metric value, which would be used to determine compliance with the
proposed regulations. Finally, a description of when changes to an existing airplane design
would trigger the need for a new certification is presented.
ES-1

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Chapter 4: Airplane Performance Model and Analysis. This chapter describes
methodologies, assumptions and data sources used to develop the airplane GHG emissions and
fuel burn inventories for the proposed standards and two alternative stringency scenarios that
were evaluated but not proposed. A description of the airplane fleet and how we project it to
evolve is first presented, followed by a description of how this fleet evolution is projected to
translate into airplane activity. Finally, the methodology is presented for determining individual
airplane flight GHG emissions, fuel consumption, and how that data is used in conjunction with
airplane activity projections to develop overall emissions inventory projections.
Chapter 5: Results of Performance Model Analysis. This chapter describes the results of the
analysis using the methodology described in Chapter 4 to determine the impacts of the proposed
standards. Included are analyses of the baseline emissions, the impact of the proposed standards,
and some sensitivity studies looking specifically at the impacts of some key assumptions.
Chapter 6: Analysis of Alternatives. This chapter provides EPA's analysis of two
alternatives to the proposed standards. The emissions reductions and costs associated with
scenarios of accelerated timing and accelerated timing in conjunction with more stringent
regulatory levels are presented.
Chapter 7: Regulatory Flexibility Analysis. This chapter describes the EPA's analysis of the
small business impacts of the proposed regulations.
For reasons discussed throughout this Draft TSD, the EPA does not project any emissions
reductions associated with the proposed GHG regulations. We do, however, project a small cost
associated with the proposed annual reporting requirement.
ES-2

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Industry Characterization
Table of Contents
Chapter 1 Industry Characterization	2
1.1	Introduction	2
1.1.1	Overview	2
1.1.2	Air Traffic	2
1.1.3	Greenhouse Gas Emissions from Aircraft	4
1.2	Market Basics	5
1.3	Product Categories	6
1.3.1	Airplanes	6
1.3.1.1	Commercial - Large Jet	7
1.3.1.2	Commercial - Regional Airplane	8
1.3.1.3	Business and General Aviation	8
1.3.2	Airplane Engines	8
1.4	Product Manufacturers	9
Table of Figures
Figure 1-1 Projection of Domestic Passenger Traffic	3
Figure 1-2 Projections of International Passenger Traffic	4
Figure 1-3 Contribution to GHG Emissions from U.S. Transportation in 2017	5
Table of Tables
Table 1-1 - Airplane Manufacturers	9
Table 1-2 - Airplane Engine Manufacturers	10
1

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Industry Characterization
Chapter 1 Industry Characterization
1.1 Introduction
1.1.1	Overview
In order to assess the impacts of the proposed regulations upon the affected industries, it is
important to understand the nature of the industries potentially affected by the regulations. In
general, this would include the manufacturers of subsonic civil jet airplanes with a maximum
takeoff mass (MTOM) greater than 5,700 kilograms (kg), the manufacturers of subsonic
propeller-driven airplanes (those powered by turboprop engines) with MTOM greater than 8,618
kg, and the manufacturers of engines for these categories of airplanes. A brief description of the
airplane and engine development process is presented in section 1.2. A general description of
these product categories is contained in section 1.3. An overview of the potentially affected
airplane and engine manufacturers is contained in section 1.4.
1.1.2	Air Traffic
General information on air traffic in the U.S. was obtained via the Federal Aviation
Administration's (FAA) Aerospace Forecast; Fiscal years 2019-2039.1 This quick overview
looks at U.S. air traffic in four general categories - domestic commercial passenger
enplanements, international commercial passenger enplanements, cargo traffic (in revenue ton
miles) and operation hours for business/general aviation.
As shown in
Figure 1-1, domestic enplanements totaled over 780 million in 2018. The FAA projects that
domestic revenue passenger miles (RPM) will increase between 2019 and 2039 at an average
annual rate of 1.9 percent.1 In contrast, RPMs for international flights are projected to grow at an
annual rate of 3.0 percent during this same period, as illustrated in Figure 1-2.
1 This projection was developed before the COVID-19 pandemic. While the projected level of aircraft operations is
affected by the COVID-19 pandemic, aviation is a growth industry that is expected to recuperate over time.
2

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Industry Characterization
U.S. Commercial Air Carriers
Domestic Enplanements by Carrier Group

1,200

1,000

c
600
u

E

a>

c
CO
400
a.

e

ill


200
204 H
^ ml 189 ¦ ¦
176 l^*
II III
837
| 690 ¦ 723 H 777 H	|
2018E 2019 2023 2027 2031
Fiscal Year
¦ Mainline ¦ Regional
2035
2039
Mainline carriers are defined as those providing service primariiy via aircraft with 90 or more seats. Regional
carriers are defined as those providing service primarily via aircraft with 89 or less seats and whose routes serve
mainly as feeders to the mainline carriers.
Figure 1-1 Projection of Domestic Passenger Traffle:
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Industry Characterization
Total Passengers To/From the U.S.
American and Foreign Flag Carriers
600
500
§M00
L
o
c
J 200
5
100
0
2018 2019 2023 2027 2031 2035 2039
Calendar Year
¦ Atlantic* ¦L.America ¦ Pacific * Canada Transborder
Source: US Customs & Border Protection data processed and released by Department of Commerce; data also
received from Transport Canada
* Per past practice, the Mid-East region and Africa are included in the Atlantic category.
Figure 1-2 Projections of International Passenger Traffic3
In the business/general aviation sector, fixed wing turbine powered airplanes were projected
to operate approximately 8 million hours in 2019. Operating hours in this sector are projected to
grow at an annual rate of 2.4 percent through 2039.
U.S. carriers flew 42.8 billion revenue ton miles (RTM) in 2018. Of this, 15.8 billion RTMs
were domestic cargo, while 27.0 billion RTMs were international cargo. Of this, approximately
80 percent of cargo is carried by all-cargo carriers, with the remainder carried by passenger
carriers. Through 2039, domestic RTM growth is projected at a rate of 1.6 percent annually,
with international RTM growth projected at 4.0 percent annually. Overall RTM growth
(domestic and international combined) is projected at a rate of 3.3 percent annually.
1.1.3 Greenhouse Gas Emissions from Aircraft
The importance of this proposed rulemaking is highlighted by the fact that GHGs from
aviation made up over 12 percent of total transportation-related GHG emissions in 2017, as
shown in Figure 1-3. Although the aircraft portion of this chart contains three aviation sectors
that would not be covered by the proposed rule (e.g., military, helicopters, and airplanes
4

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Industry Characterization
operating on aviation gasoline), these three sectors comprised well under one percent of total
transportation related GHG emissions in 2017.
2.0%
-	Cars, Light-Duty Trucks and
Motorcycles
-	Medium- and Heavy-Duty
Trucks and Buses
¦	Aircraft
Ships and Boats
¦	Rail
-	Pipeline
Source: U.S. EPA, Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2017, Tables 3-
104 and A-121, published 2019
Figure 1-3 Contribution to GHG Emissions from U.S. Transportation in 2017
1.2 Market Basics
The development of a new airplane from the ground up (i.e., a "clean sheet" design) is a very
lengthy and expensive project. As such, completely new airplane designs (known as new type
designs) are not introduced very often. The introduction of the Boeing 787, and Airbus A350
and A220 (formerly the Bombardier CSeries) in the last 10 years has marked a relatively active
period in the introduction of new type designs in the commercial airplane market.
In contrast to the development of new type designs discussed above, a more common practice
is to develop generational updates to existing airplane designs (or redesigns of the airplane). For
example, the Boeing 737 was first introduced into commercial operation in 1968. Since that
time, it has seen three redesigns - the Classic series in the 1980s, the Next Generation (NG) in
the 1990s, and the recent MAX series, introduced in 2017. These generational updates can
include any number of improvements/modifications to the previous design, but frequently
include new engines, new or redesigned wings, and updated operating systems (or some
combination of these modifications). Such updates are not considered new type designs for
purposes of certification. Rather, they are considered to be redesigns of an existing design. As
such, they are not required to undergo a completely new certification process, but instead go
through an amendment certification process of the existing type certificate. Thus, the 737 MAX
is covered under an amended version of its original 50 year-old type certificate.
This distinction between new type designs and redesigned versions of existing in-production
types is an important one for the purposes of the proposed regulations, which contain different
applicability dates and regulatory limits for new type design and in-production airplanes. An in-
production airplane is one which received it initial type certificate (TC) prior to the applicability
5

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Industry Characterization
date of the standards for new type designs. Even if an in-production airplane receives a major
redesign as described above, it would likely still be considered an in-production airplane for the
purposes of the proposed standards applicability.
Engines used on airplanes subject to the proposed standards are generally designed
specifically for the airplane type on which they will be used, with precise thrust ratings tailored
specifically to an airplane's requirements. The range and payload capacity (as indicated by
MTOM) are primary drivers of the engine specifications. Also, it is common for there to be
multiple variants of a given airplane type, with different ranges and/or stretched or shortened
fuselages. Each of these variants would similarly require a variant of the original engine type,
with a slightly different required thrust rating. It is common for an airplane manufacturer to
offer engines from two (or in some cases, three) different manufacturers on a given airplane type.
However, it is also common in the case of some smaller commercial airplanes and especially
business jets for a manufacturer to only offer a single engine option.
1.3 Product Categories
This section contains a high-level overview of the types of airplanes and engines that are
potentially affected by the proposed regulations. ICF performed a detailed industry
characterization of these industries for the EPA.4 This section, and the following section 1.4,
contain a brief summary of that report. As described in Section II of that report, ICF draws on a
number of sources to develop their industry forecasts, including working directly with the
airplane and equipment production industries, attending industry conferences and keeping up
with the latest industry news, published articles and papers. ICF synthesizes all of these sources
into their own market forecasts, which they then benchmark against global market forecasts done
by Boeing and Airbus to assure that their forecasts fall within a reasonable range.
1.3.1 Airplanes
Airplanes potentially affected by the proposed regulations can be broadly divided into three
main groups - large commercial jets, regional commercial jets, and business and general aviation
airplanes. Although there is some overlap among these categories, notably the blurring of the
line between the small end of the large commercial jet range and regional commercial jets, these
categories serve as a useful way to subdivide the world of potentially affected airplanes for
purposes of the cost and emissions analyses contained in later chapters of this document.
In general, the aviation marketplace is an international one. Manufacturers produce and sell
their airplanes for use around the world. The global prevalence of international flights (i.e.,
those that originate in one country and terminate in another) means that airplanes (especially
those in the large commercial jet category) are generally designed to operate in the international
air transport market. For example, the U.S. flight data which served as the basis for the analyses
presented later in this document show that in 2015 almost nine percent of commercial flights
originating in the U.S. were to destinations outside of the U.S. Even smaller airplanes with
ranges not suitable for international flights are often sold to countries other than a manufacturer's
home country.
Finally, while this summary focuses on passenger-carrying airplanes, it is noted that a small
number of dedicated freight airplanes are also produced which would be subject to the proposed
6

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Industry Characterization
regulations. These tend to be modifications of existing passenger airplane designs rather than
airplanes designed exclusively for freight applications.
1.3.1.1 Commercial - Large Jet
The large commercial jet category consists of a broad range of turbofan-powered airplane
types, from single-aisle airplanes seating over 100 people to very large twin-aisle airplanes that
can seat well over 500 passengers. The smallest of these are not generally used for transoceanic
international flights. Collectively, there were 1,443 large commercial jets manufactured world-
wide in 2016, with a total value of $102B. The large commercial jet category can be further
divided into four subcategories: small single aisle, small twin aisle, large twin-aisle and large
quads.
The small single aisle category consists of airplanes with a single passenger aisle and
designed to carry roughly 100-200 passengers at up to six abreast. These airplanes tend to have a
range of 60,000 kg to 97,000 kg in MTOM. Examples include the Boeing 737 series and the
Airbus A320. As previously mentioned, the line between large commercial jets and regional jets
is becoming less clear with the coming introduction of the Airbus A220 (formerly Bombardier
CSeries) and the Embraer E2 series. In terms of 2016 production, 72 percent of large
commercial jets were small single aisle. However, they only accounted for 45 percent of the
total production value.
Small twin-aisle airplanes are wide enough to feature two passenger aisles and can typically
carry 230-300 passengers at up to eight abreast. They tend to range from 186,000 kg to 308,000
kg in MTOM. Main examples of small twin-aisle airplanes are the Boeing 787 and the Airbus
A330. This subcategory accounted for 10 percent of the 2016 production and 17 percent of the
production value.
Large twin-aisle airplanes also feature two passenger aisles but with wider fuselages that can
accommodate up to 400 passengers at up to eight abreast and with MTOM from 233,000 kg to
around 350,000 kg. An example of a large twin-aisle is the Boeing 777, although the large
variants of the Airbus A330 and A350 (small twin-aisles) blur the distinction between small and
large twin-aisles. This subcategory accounted for 15 percent of the 2016 production and 30
percent of the production value.
The last subcategory of large commercial jets is the large quad. These airplanes are also twin-
aisle, but they are large enough to require four engines (as opposed to the three previously
discussed subcategories which are typically powered by two engines). These airplanes can carry
as many as 575 passengers in ten-abreast configuration. Examples include the Boeing 747 and
the Airbus A380. This subcategory accounted for 3 percent of the 2016 production and
accounted for 8 percent of the production value. However, demand for large quad airplanes is
declining dramatically for multiple reasons. First, the increasing efficiencies, range and
passenger (and payload) capacity of the large twin-aisle airplanes has made them attractive as
replacements for large quads. Second, the development of Extended-range Twin-engine
Operational Performance Standards (ETOPS) has allowed twin-engine airplanes to safely service
routes previously only serviced by airplanes with more than two engines. Finally, the overall
growth in the commercial passenger aviation market has resulted in making more city pairs
profitable using direct flights with smaller airplanes, thus reducing the demand for large quads to
service the "hub and spoke" model of passenger air traffic. Although the future of the large quad
7

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Industry Characterization
market has been the subject of much debate in the aviation world, ICF's 2018 analysis projected
that production of large quad airplanes is likely to end altogether by the mid-2020s. As
discussed further in Chapter 5 and Chapter 6, since the ICF analysis was completed, Airbus has
announced plans to end production of the A380 in 2021.
Total sales of large commercial jets are projected to climb to almost 1,800 units in 2021 but
drop back to around 1,600 units in 2026. More significantly, it is expected that the large quad
subcategory will shrink dramatically in this time frame.
1.3.1.2	Commercial - Regional Airplane
The regional commercial airplane category can be divided into two subcategories: the
regional jet and the regional turboprop. Regional jets are turbofan-powered jets which typically
carry 50-100 passengers with an MTOM in the range of 19,000 kg to 60,700 kg. Examples
include the Embraer EJet and the Bombardier CRJ. Regional turboprops are also powered by
turbine engines, but the engines' power is instead used to drive a propeller. Regional turboprops
tend to be smaller than their jet counterparts, with an MTOM range of 18,600 kg to 30,000 kg
and a capacity of around 40 to 80 passengers. Examples include the ATR 42/72 and the
Bombardier Q400. While turboprops tend to be more fuel-efficient than their turbofan
counterparts, they are also slower and have higher levels of cabin noise which somewhat serves
to offset the appeal of that better fuel efficiency.
There were 267 regional commercial airplanes produced in 2016, with a total value of S6.3B.
Regional jets accounted for 57 percent of the production volume and 69 percent of the
production value. Production of regional airplanes is projected to remain relatively steady
through 2026.
1.3.1.3	Business and General A viation
The business jet and general aviation market includes a wide range of small, turbofan-
powered airplanes designed for business and personal use. These airplanes range from 6,200 kg
to 48,000 kg MTOM, with capacities of 6 to 19 passengers. There were 567 business and
general aviation airplanes produced in 2016, with a market value of $16.8B. Production of this
category of airplanes is expected to steadily grow to well over 800 units in 2026. The main
manufacturers in this market include Embraer, Dassault, Gulfstream, Cessna and Bombardier.
1.3.2 Airplane Engines
There are two main types of engines potentially affected by the proposed regulations -
turbofans and turboprops. While both are turbine engines, they differ in their mode of
propulsion. A turbofan engine utilizes the mechanical energy of the turbine to power a ducted
fan which provides the majority of the propulsion. However, the air that flows through the
turbine itself and exits as combustion exhaust also provides a portion of a turbofan's propulsion.
In contrast, a turboprop utilizes the turbines mechanical energy to power an open propeller,
which provides the entirety of turboprop's propulsion. In terms of utilization on airplanes
covered by the proposed regulations, turbofans are used across the entire spectrum of airplanes,
from the smallest business jets to the largest commercial airplanes. In contrast, turboprops tend
to be limited in use to commercial regional airplanes.
8

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Industry Characterization
There were 5,069 commercial engines produced in 2016 for airplanes that would be subject to
the proposed regulations. Large commercial jet engines accounted for 64 percent, while regional
jet engines accounted for 12 percent and business/general aviation engines accounted for the
remaining 24 percent. In terms of production value, large commercial airplane engines
accounted for 89 percent of the $38B total, with regional airplane at four percent and
business/general aviation accounting for the remaining seven percent.
Commercial engine production is driven by airplane production and is expected to grow to
5,817 units in 2026. Most of this growth is expected to be in the business/general aviation
sector.
1.4 Product Manufacturers
This section contains a brief overview of the manufacturers of products that would be covered
by this proposed rule. Some of this information (i.e., each manufacturer's number of employees)
was used in the screening analysis for the Small Business Flexibility Analysis (SBFA) which
evaluates the potential impacts of the proposed rule on small entities. That analysis is discussed
in Chapter 7.
Table 1-1 - Airplane Manufacturers
Manufacturer
Categories3
Main Products
Employee Countb
Airbus
Comm
A220, A320, A330, A350, A380
136,574
ATR
B/GA
ATR 42, ATR72
1,300°
Boeing
Comm
737, 747, 767, 777, 787
147,683
Bombardier
Comm, B/GA
CRJ, Q400
61,900
Cessna
B/GA
Citation
36,000
CO MAC
Comm
ARJ
Unavailable
Dassault
B/GA
Falcon
11,942
Embraer
Comm, B/GA
Legacy, Phenom, ERJ, E2
19,357
Gulfstream
B/GA
G150, G280, G450, G550, G650
13,313




Irkut
Comm
MS-21
10,000
Mitsubishi
Comm
MRJ
68,247
Pilatus
B/GA
PC-24
1,905
Sukhoi
Comm
Superjet
10,000
a.	Comm = commercial, B/GA = business and general aviation
b.	In some cases, the employee count is that of the parent company
c.	ATR is jointly owned by Airbus and Leonardo. Thus, the parent companies have significantly more than the
1,500 employee cutoff used to determine whether a company is a small entity. See Chapter 7.
9

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Industry Characterization
Table 1-2 - Airplane Engine Manufacturers
Manufacturer
Categories3
Main Products'5
Employee Count
CFM International
Comm
CFM56, LEAP
NAC
Engine Alliance
Comm
GP7200
NAd
GE
Comm, B/GA
GEnx, GE9x, CF6, CF34, Passport

Honeywell
B/GA
HTF7000, TFE731
40,000
International Aero
Comm
V2500
NAe
Pratt & Whitney
Comm
PW4000, GTF
35, 104
Pratt & Whitney Canada
B/GA
PW100, PW500, PW800
9,200
PowerJet
Comm
SAM 146
NAf
Rolls-Royce
Comm, B/GA
Trent series, BR700, AE3007
49,900
Safran
B/GA
Silvercrest
15,700
Williams International
B/GA
FJ44
<1,000
a.	Comm = commercial, B/GA = business and general aviation
b.	This is not an exhaustive list, and only includes products that are potentially affected by the proposed
regulations. It also includes some products which are still under development but nearing commercial
introduction.
c.	CFM International is a joint venture between GE and Safran.
d.	Engine Alliance is a joint venture between GE and Pratt & Whitney.
e.	International Aero is a joint venture between Pratt & Whitney, Japanese Aero Engine Corporation and MTU
Aero Engines.
f.	Powerjet is a joint venture between Safran and NPO Saturn.
10

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Industry Characterization
REFERENCES
1	FAA, 2020: FAA Aerospace Forecast; Fiscal Years 2019-2039, U.S. Federal Aviation Administration, TC18-
0004. Accessed March 18, 2020 at https://www.faa.gov/data research/aviation/aerospace forecasts/media/FY2019-
39 FAA Aerospace Forecast.pdf (last accessed March 20. 2020).
2	See Reference #1
3	See Reference #1
4ICF, 2018: Aircraft COi Cost and Technology Refresh and Industry Characterization, Final Report, EPA Contract
Number EP-C-16-020, September 30, 2018.
11

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Technology and Cost
Table of Contents
Chapter 2 Technology and Cost	14
2.1	Overview	15
2.2	Technology Principles	16
2.2.1	Short- and Mid-Term Methodology	16
2.2.2	Long-Term Methodology	25
2.2.2.1	Fuel Burn Reduction Prospect Index	25
2.2.2.2	Market Driver Index	26
2.2.2.3	Metric Value Improvement Acceleration Index	27
2.2.2.4	Example for Long-Term Metric Value Forecast	28
2.2.2.5	Long-Term Replacement Airplane Analysis (2030-2040)	 31
2.3	Technologies	32
2.3.1	Airframe Technologies	34
2.3.1.1	Advanced Wingtip Devices	34
2.3.1.2	Adaptive Trailing Edge	35
2.3.1.3	Aft Body Redesign	35
2.3.1.4	Hybrid Laminar Flow Control - Empennage	35
2.3.1.5	Riblet Coatings	36
2.3.1.6	ECS Aerodynamics and On-Demand ECS Scheduling	37
2.3.2	Engine Technologies	37
2.4	Technology Application	38
2.4.1	Technology Responses	39
2.4.2	One Percent Additional Design Margin for Technology Response	41
2.5	Estimated Costs	41
2.5.1	Non-Recurring Costs	41
2.5.1.1	Non-Recurring Costs Component Proportions	42
2.5.1.2	Non-Recurring Cost Scaling Factors	43
2.5.2	Comparing the EPA NRC to ICAO/CAEP NRC for International Airplane CO2
Emission Standards	46
2.5.3	Certification Costs	50
2.5.4	Recurring Costs	51
2.5.5	Reporting Requirement Costs	52
2.6	Airplane Fuel Savings	52
2.7	Fuel Prices	56
2.8	Summary of Benefits and Costs	56
Appendix A	- Airframe Technologies	57
Appendix B	- Engine Technologies	63
Appendix C	- Example Supply Curves by Airplane Category	64
12

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Technology and Cost
Table of Figures
Figure 2-1.- Expected Value Technology Impact	17
Figure 2-2 Graphical Form of Metric Value Index Scoring	28
Figure 2-3. Example Supply Curve	40
Figure 2-4. Single Aisle Category Non-Recurring Cost Component Proportions	43
Figure 2-5. Example Non-Recurring Cost Scaling by Airplane Category - Large Incremental Update	45
Figure 2-6. CAEP NRC Surface's Coefficient D (left) and f (AMV) (right) Formulation	48
Figure 2-7. CAEP Cumulative CO2 (Megatonnes) Reductions from the Effective Date to 2040 	54
Figure 2-8. CAEP Change in Cumulative Costs for 2028 Effective Date'	55
Figure 2-9 Example Supply Curve for Small BGA	64
Figure 2-10 Example Supply Curve for Large BGA	65
Figure 2-11 Example Supply Curve for Turboprop	65
Figure 2-12 Example Supply Curve for Regional Jet	66
Figure 2-13 Example Supply Curve for Single Aisle	66
Figure 2-14 Example Supply Curve for Small Twin Aisle	67
Figure 2-15 Example Supply Curve for Large Twin Aisle	67
Figure 2-16 Example Supply Curve for Large Quad	68
Table of Tables
Table 2-1 - Airplane Metric Value (MV) Forecast/Reduction (PIANO Data)	21
Table 2-2 Metric Value Index Scoring	27
Table 2-3 Single Aisle Example for Fuel Burn Reduction Prospect Index	29
Table 2-4 Other Airplane Category Examples of Fuel Burn Reduction Prospect Index	30
Table 2-5 Single Aisle Example for Metric Value Improvement Acceleration Index	30
Table 2-6 Long-Term Potential Replacement Airplanes	31
Table 2-7 Airframe and Systems Technologies	33
Table 2-8 Engine Technologies	33
Table 2-9. Representative Engine Performance Improvement Packages	38
Table 2-10 - Non-Recurring Cost Component Scaling Factor Sources	44
Table 2-11 - Non-Recurring Cost Component Scaling Factors	44
Table 2-12 Comparison Results of EPA NRC to CAEP NRC Surface ($ Billions) - Part 1	49
Table 2-13 Comparison Results of EPA NRC to CAEP NRC Surface ($ Billions) - Part 2	50
Table 2-14 Fuel Burn and Costs Impacts for Advanced Wingtip Devices	58
Table 2-15 Fuel Burn and Costs Impacts for Adaptive Trailing Edge	59
Table 2-16 Fuel Burn and Costs Impacts for Aft Body Redesign	60
Table 2-17 Fuel Burn and Costs Impacts for Hybrid Laminar Flow Control - Empennage	60
Table 2-18 Fuel Burn and Costs Impacts for Riblet Coatings	61
Table 2-19 Fuel Burn and Costs Impacts for ECS Aerodynamics and On-Demand ECS Scheduling	62
Table 2-20 Fuel Burn and Costs Impacts for Engine Technologies	63
Table of Equations
Equation 2-1 Metric Value Reduction	18
Equation 2-2: Calculation of Metric Value Reduction - Advanced Wingtip Devices for A330 in 2018	19
Equation 2-3: Calculation of Metric Value Reduction - Adaptive Trailing Edge for A330 in 2018	19
Equation 2-4 Function of CAEP's NRC Surface	47
Equation 2-5 Equation to Calculate AMV	48
Equation 2-6 Equation to Calculate Normalized MV Improvement	48
13

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Technology and Cost
Chapter 2 Technology and Cost
As described in section VII of the preamble, the EPA and FAA participated in ICAO/CAEP's
analysis that informed the adoption of the international airplane CO2 standards (ICAO Airplane
CO2 Emission Standards). A summary of that analysis was published in the report of
ICAO/CAEP's tenth meeting,5 which occurred in February 2016. This summary is useful in
giving an overview of the analytical results used by CAEP in deciding on the final standards.
However, due to the commercial sensitivity of much of the underlying data used in this ICAO
analysis, the ICAO-published report (which is publicly available) provides only limited
supporting data for the ICAO analysis. This EPA Draft TSD compares the ICAO analysis to the
EPA analysis.
For the purposes of the proposed GHG standards, the EPA presents an evaluation based on
publicly available and independent data. In support of this work, the EPA had an analysis
conducted of the technological feasibility and costs of the international Airplane CO2 Emission
Standards through a contractor (ICF) study.6'7 The results developed by the contractor include
estimates of technology responses and non-recurring costs for the proposed domestic GHG
standards, which are equivalent to the international Airplane CO2 Emission Standards.
Technologies and costs needed for airplane types to meet the proposed GHG standards were
analyzed and compared to the improvements that are anticipated to occur in the absence of
standards (business as usual improvements).
The ICF study is an update to work performed in support of the 2015 U.S. EPA Aircraft
Greenhouse Gas Emissions Advance Notice of Proposed Rulemaking (henceforth the "2015
ANPR").8 At that time, the EPA contracted with ICF to develop estimates of technology
improvements and responses needed to modify in-production airplanes to comply with the
international Airplane CO2 Emission Standards. ICF conducted a detailed literature search,
performed a number of interviews with industry leaders, and did its own modeling to estimate
the cost of making modifications to in-production airplanes.9 Subsequently, for this proposed
rulemaking, the EPA contracted with ICF to update its analysis (herein referred to as the "2018
ICF updated analysis"), which is located in the docket for this proposed rulemaking.10,11 It had
been three years since the initial 2015 ICF analysis was completed, and with the fast pace of
advancing aviation technology the status of CO2 technology improvements has changed in this
short time frame.111 The 2018 ICF updated analysis was peer-reviewed by multiple independent
II	The data sources for the 2018 ICF updated analysis are detailed in section II. 1.2 of this ICF analysis (or this ICF
report), including a description of ICF's broad and thorough aviation market interview program on technology
performance, modeling approach and methodology, commercial feasibility, and costs. ICF conducted over 40
interviews with an expansive cross-section of key aviation individuals in the industry - airframe, engine, and
systems manufacturers, and airlines — and in university/research organizations. In addition, ICF leveraged
knowledge they had gained through past and ongoing project work on in-depth cost and performance models for
aviation.
III	The ICAO test procedures for the international airplane CO2 standards measure fuel efficiency (or fuel burn).
Only two of the six well-mixed GHGs—CO2 and N2O are emitted from airplanes. The test procedures for fuel
efficiency scale with the limiting of both CO2 and N2O emissions, as they both can be indexed on a per-unit-of-
fuel-burn basis. Therefore, both CO2 and N2O emissions can be controlled as airplane fuel burn is limited. Since
limiting fuel burn is the only means by which airplanes control their GHG emissions, the fuel burn (or fuel
efficiency) reasonably serves as a surrogate for controlling both CO2 and N2O.
14

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Technology and Cost
subject matter experts, including experts from academia and other government agencies, as well
as an independent technical expert.11
2.1 Overview
As described in the preamble, ICAO/CAEP traditionally sets standards that are technology-
following standards, rather than technology-forcing standards. This means that the international
standards reflect a level of emissions performance that is already achieved by some portion of
current in-production airplanes. For the international Airplane CO2 Emission Standards,
ICAO/CAEP determined in 2012 that all technology responses for its analysis would have to be
based on technology that would be in common use by the time the standards were to be decided
upon in 2016 or shortly thereafter (ICAO/CAEP's analysis was completed in 2015 for the
February 2016 ICAO/CAEP meeting). This generation of technology or technical feasibility was
defined within CAEP as "... any technology expected to be demonstrated to be safe and
airworthy and proven Technology Readiness Level (TRL) 8 by 2016 or shortly thereafter"1V
(approximately 2017) — and "expected to be available for application in the short term over a
sufficient range of newly certificated aircraft" (approximately 2020).12 This means that the
analysis that informed the international standards considered the emissions performance of in-
production and on-order or in-developmentv airplanes, including types that would first enter into
service by about 2020.
In assessing the airplane GHG standards proposed today, the 2018 ICF updated analysis,
which was completed a few years after the ICAO analysis, uses a different approach for
technology responses. ICF based these responses on technology that would be available at TRL8
by 2017 and assumed continuous improvement of fuel efficiency metric values for in-production
and in-development (or on-order) airplanes from 2010 to 2040 based on the incorporation of
these technologies onto these airplanes over this same timeframe." Also, ICF considered the end
of production of airplanes based on the expected business as usual status of airplanes (with the
continuous improvement assumptions). The ICF approach differed from ICAO/CAEP's analysis
for years 2015 to 2020 and diverged even more for years 2021 and after. We believe this
approach provides a more up to date assessment compared to ICAO/CAEP's analysis.™ Since
ICF used the proposed effective dates in their analysis of the proposed airplane GHG standards
(for new type design airplanes 2020, or 2023 for airplanes with less than 19 seats, and for in-
production airplanes 2028), ICF was able to differentiate between airplane GHG technology
improvements that would occur in the absence of the proposed standards compared to
lv TRL is a measure of Technology Readiness Level. CAEP has defined TRL8 as the "actual system completed and
'flight qualified' through test and demonstration." TRL is a scale from 1 to 9, TRL1 is the conceptual principle,
and TRL9 is the "actual system 'flight proven' on operational flight." The TRL scale was originally developed by
NASA. ICF International, CO2 Analysis of C02-Reducing Technologies for Airplanes, Final Report, EPA
Contract Number EP C 12 011, see page 40, March 17, 2015.
v Airplanes that are currently in-development but were anticipated to be in production by about 2020.
V1 ICF used the terminology, "CO2 metric values," in their updated analysis, consistent with ICAO, when referring to
fuel efficiency metric values.
vu ICAO/CAEP did not consider continuous improvement of metric value (from 2010 to 2040) for in-production and
project (or on-order) airplanes based on incorporating 2016/2017 TRL8 technologies (or 2017 technologies).
Instead, ICAO/CAEP considered transition pairs, where project airplanes (or on-order airplanes) would replace
their paired in-production airplanes, and these transitions typically represented a step-change in technology and
MV improvement.
15

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Technology and Cost
technology improvements/responses that would be needed to comply with the proposed
standards.
2.2 Technology Principles
2.2.1 Short- and Mid-Term Methodology
ICF analyzed the feasible technological improvements to new in-production airplanes and the
potential GHG emission reductions they could generate. For this analysis, ICF created a
methodological framework to assess the potential impact of technology introduction on airplane
GHG emissions for the years 2015-2029 (short- and mid-term timeframe). Baseline emission
rates over the ICAO/CAEP test procedure/cycle, as described in Chapter 3 of the Draft TSD and
section III of the preamble, were generated using PIANO data (PIANO is a physics-based
airplane performance model).vm These emission rates are in units of kilograms of fuel burned
per kilometer and are referred to as metric values.
ICF's framework included six steps to estimate annual metric value improvements for
technologies that are being or will be applied to in-production airplanes. First, ICF identified the
technologies that could reduce GHG emissions of new in-production airplanes. Second, ICF
evaluated each technology for the potential GHG reduction and the mechanisms by which this
reduction is achieved. Third and fourth, the technologies were passed through technical success
probability and commercial success probability screenings, respectively. These first four steps
were analyzed by airplane category. Fifth, individual airplane differences were assessed within
each airplane category to generate GHG emission reduction projections by technology at the
airplane family level (e.g., 737 family). Finally, ICF extended the GHG emission reduction
projections by technology to the airplane variant level or airplane model level (e.g., 737-700,
737-800, etc.).
ICF refers to their methodological framework for projection of the metric value improvement
or reduction as the expected value methodology. The expected value methodology is a
projection of the annual fuel efficiency metric value improvement1* from 2015-2029 for all the
technologies that would be applied to each airplane, or business as usual improvement in the
absence of a standard. Figure 2-1 is a flow chart of the expected value methodology (or expected
vm To generate metric values, the 2015 ICF analysis and 2018 ICF updated analysis used PIANO (Project Interactive
Analysis and Optimization) data so that their analyses results can be shared publicly. Metric values developed
utilizing PIANO data are similar to ICAO metric values. PIANO is the Aircraft Design and Analysis Software by
Dr. Dimitri Simos, Lissys Limited, UK, 1990-present; Available at www.piano.aero (last accessed March 17,
2020). PIANO is a commercially available aircraft design and performance software suite used across the
industry and academia.
lx Also referred to as the constant annual improvement in fuel efficiency metric value.
16

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Technology and Cost
value technology impact methodology*) .X1,X11,13,14 The elements in the flow chart are described in
more detail later in this chapter.
Key Steps	Output
Identify the technologies that can reduce
C02 emissions if installed on new In-
Production airplanes
Technology List
Identifythe magnitudeand meansby which
these technologies reduce C02 emissions
by airplane category
Unconstrained
Technology Impact
Matrix
Assess the probability of technical success
by technology and airplanecategory
Technical Success
Screened Matrix
Assessthe probability of commercial
success by t e ch n o I ogy a n d a i rpl a n e category
COj Emissions
Reduction Forecast
(by airplane category)
Drive the forecasted C02 reductions down to
the airplane family level within airplane category
COz Emissions
Reduction Forecast
(by airplane family)
Exte n d t h e f o re ca st C02 re d u ct i o n s d o w n to
airplane variantlevel based on airplane
family level improvements
CO, Emissions
Reduction Forecast
(by airplane variant)
Figure 2-1.- Expected Value Technology Impact
As a modification to the 2015 ICF analysis, the 2018 ICF updated analysis extended the
metric value improvements at the airplane family level to the more specific airplane variant
level. Thus, to estimate whether each airplane variant (e.g., 737-700, 737-800, etc.) complied
with the proposed GHG standard, ICF projected airplane family metric value reductions to a
baseline (or base year) metric value of each airplane variant. Equation 2-1 below shows this
x The use of the term, "expected value technology impact methodology," versus "expected value methodology" in
the title of Figure 2-1 is to highlight the following: for the short- and mid-term analysis we evaluated each
technology and the level or amount of fuel burn and metric value impact (or improvement) the technology
contributes to each airplane variant.
X1 ICF based technology responses on technology that was TRL8 in 2017 — considering continuous improvements of
in-production and project (or on-order) airplane metric values from the incorporation of these technologies in the
2015 to 2029 timeframe (for the short- and mid-term timeframe). Also, in this same time frame, ICF estimated
the expected production status of in-production airplanes based on business as usual improvements (or the
continuous improvement assumptions). The approach differing compared to ICAO/CAEP's analysis for years
2015 to 2020 and diverging even more for years 2021 and after - due to ICF including the continuous
improvement assumptions).
xu Through interviews, prior project work, and extensive literature research, ICF identified the sources of airplane
fuel burn improvement. Subsequently, by going through the major systems within an airplane (aerostructures,
engines, airframe systems, interior, avionics), ICF then determined the range of magnitude of MV improvements,
its applicability to each airplane size category, and other drivers as listed in the diagram (such as probability of
technical feasibility, commercial feasibility, etc.).
17

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Technology and Cost
approach. ICF used this approach to estimate metric values for 125 airplane models, and this
approach allows for a comparison of the estimated metric value for each airplane model to the
level of the proposed GHG standards at the time the standards would go into effect. Table 2-1
below provides the results of the analysis of metric value reduction (i.e., fuel efficiency
improvement) by airplane variant for the years 2015, 2018, 2020, 2023, and 2028 (the 2015-2029
timeframe) using the short- and mid-term methodology, and 2030 and 2040 (the 2030-2040
timeframe) using the long-term methodology, which is described later in section 2.2.2
Equation 2-1 Metric Value Reduction
Metric value reduction
= Technology applicability percentage
*	commercial feasibility factor * probability of technical success
*	Average metric value benefit of technology by airplane type
where:
•	Technology applicability percentage111 = percentage representing the metric value
benefit a technology would provide for an airplane family (some technologies only
realize partial benefits on certain particular airplane families);
•	Commercial feasibility factor = factor representing the probability of commercial
success a technology would provide for an airplane family;
•	Probability of technical success = factor representing the probability of technical success
a technology would provide for an airplane family; and,
•	A verage metric value benefit of technology by airplane type = absolute metric value
reduction of a technology by airplane size category;X1V
xm For technology applicability percentage, we accounted for partial applicability of an MV reducing technology for
an airplane model. Typically, in-development airplanes will have lower baseline metric values (improved or
better performing metric values) compared to legacy airplanes, since they have more advanced technologies
implemented within the initial launch of the airplane. Consequently, there will be fewer incremental
improvements available from future technologies for in-development airplanes. Due to the addition of a number
of new in-development airplanes into the analysis, ICF modified the technology applicability matrix from
analyzing each technology in a binary manner (i.e. technology can only be fully applicable or fully un-
applicable), to a continuous manner so that partial impacts of technologies could be applied to new airplane
models (i.e. percentage magnitude of a fuel burn impact will each technology provide).
Xlv The initial average metric value benefit assessment is conducted at the airplane size category level. Then, we use
this airplane size category level assessment for each technology and apply the technology applicability percentage
for each in-production airplane variant, which extends the magnitude of metric value benefit from the size
category level to the variant level.
As an example, the winglet is assessed to have a 3.5% metric value benefit for widebodies (airplane size category
level). We then take this assessment and multiply for the MS-21 airplane, which we assess will only reap 50% of
the benefit (variant level) [3.5%*50%]. Another example is the 777X airplane, which we assess will reap none of
the benefit (variant level) [3.5%*0%]; because winglets are not applicable to 777X wing design.
18

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Technology and Cost
Example calculation #1 of metric value reduction — advanced wingtip devices for A330
in year 2018:
•	Technology applicability percentage of advanced wingtip devices (A330): 100%
•	Commercial feasibility factor (advanced wingtip devices in 2018): 10%
•	Probability of technical success (advanced wingtip devices in 2018): 100%
•	Average metric value benefit of technology by airplane type (large twin aisle): 3.5%
Equation 2-2: Calculation of Metric Value Reduction - Advanced Wingtip Devices for A330 in 2018
= technology applicability percentage of advanced wingtip devices (i4330)
*	commercial feasibility factor (advanced wingtip devices in 2018)
*	probability of technical success (advanced wingtip devices in 2018)
*	average metric value benefit of technology by airplane type (large twin aisle)
= (100% * 10% * 100%) * 3.5% = 0.35%
This means that 0.35% of MV benefit in A330 in 2018 is attributable to advanced wingtip
devices. To obtain the total MV reduction in a particular year, we would perform this calculation
for all applicable technology and then sum up the results of MV benefit for each technology.
Example calculation #2 of metric value reduction - adaptive trailing edge for A330 in
year 2028:
•	Technology applicability percentage of adaptive trailing edge (A330): 100%
•	Commercial feasibility factor (adaptive trailing edge in 2028): 15%
•	Probability of technical success (adaptive trailing edge in 2028): 100%
•	Average metric value benefit of technology by airplane type (large twin aisle): 2.0%
Equation 2-3: Calculation of Metric Value Reduction - Adaptive Trailing Edge for A330 in 2018
= technology applicability percentage of adaptive trailing edge (i4330)
*	commercial feasibility factor (adaptive trailing edge in 2028)
*	probability of technical success (adaptive trailing edge in 2028)
*	average metric value benefit of technology by airplane type (large twin aisle)
= (100% * 15% * 100%) * 2.0% = 0.3%
This means that 0.3% of MV benefit in A330 in 2028 is attributable to adaptive trailing edge.
In addition, ICF projected which airplane models would end their production prior to the
effective date of the proposed GHG standards. These estimates of production status, at the time
the standards would go into effect, further informed the projected response of airplane models to
the proposed standards.
19

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Technology and Cost
As described earlier in section 2.2.1, the short- and mid-term methodology (2015-2029) is
appropriate for the EPA proposed GHG standards because it is from assumptions based on the
actual effective dates of the proposed GHG standards. A description of the airplane and engine
technologies, which are the primary basis for these assumptions for the short- and mid-term
methodology, is provided later in section 2.3.
20

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BOEING
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BOEING
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BOEING
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-------
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Market Category
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FAL7X
ERJLEG
GVI
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Learjet 40XR
Learjet 45XR
Learjet 60XR
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CNA525B
CNA525C
CNA560-XLS
CNA680
CNA750
FAL2000LX
EMB505
G280
GULF150
Learjet 70
Learjet 75
CNA680-S
CNA750-X
PC-24

-------
Technology and Cost
2.2.2 Long-Term Methodology
To project metric value improvements for the long-term, years 2030-2040, ICF generated a
different methodology compared to the short- and mid-term methodology. The short- and mid-
term methodology is based on forecasting metric value improvements due to the implementation
of specific existing technologies. ICF projects that in about the 2030 timeframe a new round of
technology implementation would begin.15 For this reason, ICF developed a different method
for predicting metric value improvements for the long term. For 2030 or later, ICF used a
parametric approach to project annual metric value improvements.16 This approach included
three steps. First, for each airplane type, technical factors were identified that drive fuel burn
and metric value improvements in the long-term (i.e., propulsive efficiency, friction drag
reduction), and the fuel burn reduction prospect index, which is described below in section
2.2.2.1, was estimated on a scale of 1 to 5 for each technical factor. Second, a long-term market
prospect index was generated on a scale of 1 to 5 based on estimates of the amount of potential
research and development (R&D) put into various technologies for each airplane type. Third, the
long-term market prospect index for each airplane type was combined with its respective fuel
burn reduction prospect index to generate an overall index score for their metric value
improvements. A low overall index score would indicate that the airplane type will have a
decelerated annual metric value reduction, and a high overall index score would indicate an
accelerated annual metric value improvement (relative to an extrapolated short- and mid-term
annual metric value improvement).xv
As discussed earlier in section 2.1, ICAO/CAEP's analysis did not include a long-term
technology assessment for 2030-2040, but instead focused on technology that would have been
in operation by 2016/2017 (and considered the emissions performance of in-production and on-
order or in-developmentxvl airplanes, including types that would first enter into service by about
2020). ICF's long-term approach is appropriate for the EPA proposed GHG standards because it
derives reasonable assumptions based on the best available information for this timeframe.
2.2.2.1 Fuel Burn Reduction Prospect Index
The fuel burn reduction prospect index is a projected ranking of the feasibility and readiness
of technologies (for reducing fuel burn) to be implemented for 2030 and later. For the fuel burn
reduction prospect index, the technology factors that mainly contribute to fuel burn were
identified.17 These factors included the following engine and airframe technologies as described
below: (Engine) sealing, propulsive efficiency, thermal efficiency, reduced cooling, and reduced
power extraction and (Airframe) induced drag reduction and friction drag reduction. A number
of these technology factors are described in more detail later in section 2.3. Also, the 2018 ICF
updated analysis provides further details on the technology factors.
• Sealing: Imperfect air sealing in the engine leads to leaking that diminishes the engine
efficiency (especially in the engine compressor) that ultimately increases the fuel burn.
xv Accelerated metric value improvement rate means that the metric value is improving at an accelerated rate (i.e.,
faster than the historical rate). Decelerated metric value improvement rate means that the metric value is
improving at a decelerated rate (i.e., slower than the historical rate).
XV1 Airplanes that are currently in-development but were anticipated to be in production by about 2020.
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Technology and Cost
•	Propulsive efficiency: This is the part of the kinetic energy added to the air that
contributes to thrust. (Not to be confused with the overall propulsive efficiency, which is
the product of the propulsive efficiency and the thermal efficiency). Increasing bypass
ratio is the primary approach to increase propulsive efficiency and thus reduce fuel burn.
•	Thermal efficiency: This is the efficiency with which the chemical energy of the fuel is
converted into mechanical power. The primary approach to increase the thermal
efficiency is by increasing the turbine entry temperature.
•	Reduced cooling: To cool the hotter parts of the engine, bleed air is taken from the engine
compressor stage. This leads to a loss that on its own that increases the fuel burn, but
contributes to improving the thermal efficiency by making it possible to raise the turbine
entry temperature.
•	Reduced power extraction: Bleed air is commonly used for other airplane systems (anti-
icing, cabin pressurization, pneumatic actuators, etc.). In addition to power extraction
through bleeding air, shaft power may be extracted through electric generators to power
airplane systems. The less the power extraction, the less the fuel burn.
•	Induced drag reduction: This type of drag is induced by the generation of lift. For a given
lift, this can be decreased by optimizing the distribution of pressures on the wing through
aerodynamic shaping, increasing wingspan, and adding wing tip devices. The lower the
induced drag, the lower the fuel burn.
•	Friction drag reduction: This type of drag is due to mechanical friction of the air with the
airplane surface. This can be decreased by reducing the exposed area, improving surface
finishing, and through aerodynamic shaping. The lower the friction drag, the lower the
fuel burn.
•	Profile drag reduction: This type of drag is due to flow separation that causes a turbulent
wake where energy is dissipated. Profile drag can be decreased by aerodynamic shaping.
The technology factors were each scored on three dimensions that were considered to drive
the overall fuel burn reduction effectiveness in the latter end of the forecast years. These three
scoring dimensions include the following criteria:
•	Effectiveness of technology in improving fuel burn;
•	Likelihood of technology implementation; and
•	Level of research effort needed.
The scoring dimensions of the effectiveness of technology in improving fuel burn and level of
research effort needed were considered the primary drivers in the technical factors because of
past experience. These two factors are the most important since the effectiveness of a
technology in decreasing fuel burn (or decreasing the metric value) would most incentivize
manufacturers to pursue research, while the level of research effort would direct how
economically feasible a technology is. Thus, heavier weightings were allocated to these two
factors (40 percent weighting on each of these factors) compared to likelihood of implementation
(20 percent weighting on this factor). The scoring of each of the technical factors on the three
dimensions was averaged to develop an overall fuel burn reduction prospect index.
2.2.2.2 Market Driver Index
Market driver indices for each airplane type18 were developed based on where the market is
projected to shift towards in the latter end of the forecast years. The extent of research and
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Technology and Cost
development that manufacturers will carry out was also weighted towards this shift. Engine
manufacturers were projected to make more efficient engines that would enable more point-to-
point travel, subsequently decreasing the need for large quad airplanes and creating more market
demand and more focus on improvements for single aisle and small twin-aisle airplanes. Recent
technology developments have been focused on re-engine improvements, and thus, it was
anticipated that there would be ample possibilities for an airframe redesign in the next round of
technological improvement due in the early 2030s. In addition, it was projected that the number
of business jets, turboprops, and regional jet airplanes would grow slightly slower compared to
the recent past (or the growth in the number of these airplanes would be relatively stagnant in the
outbound years). We expect the highest long-term growth in number of airplanes to occur in the
single aisle and small twin aisle airplane categories (the highest near- and mid-term growth is
also anticipated in these two airplane categories).19
2.2.2.3 Metric Value Improvement Acceleration Index
The fuel burn reduction prospect index was combined with the market driver index via
weighted average for each airplane type to calculate the overall metric value improvement
acceleration index.20 A scoring of 1 was a 60 percent improvement rate relative to extrapolated
short/mid-term annual metric value improvement, a scoring of 3 was a continued extrapolated
short/mid-term annual metric value improvement, and a scoring of 5 was a 140 percent
improvement rate relative to extrapolated short/mid-term annual metric value improvement.
Table 2-2 below shows the improvement rates for this assessed index scoring. (A little more
weighting was put on the technological factors (or fuel burn reduction prospect index) with a 65
percent scoring weight, compared to market factors (market driver index) with a 35 percent
scoring weight, because of past experience. The weighting is reasonable since while fuel burn
prospects are the most important factor for manufacturers, the manner in which the overall
market is evolving (e.g., more single aisle airplanes) would affect the way manufacturers
apportion their research efforts.) Finally, the short/mid-term metric value improvement impact
estimates described earlier were extended to the end of the long-term forecast timeframe (2040)
and overall metric value improvement acceleration index scoring developed by each airplane
type was applied to those estimates.
Table 2-2 Metric Value Index Scoring
MV Acceleration
Index Scoring
Improvement rate (relative to extrapolated
short/mid-term annual MV improvement)
1
60%
2
80%
3
100%
4
120%
5
140%
Figure 2-2 provides the graphical form of the improvement rates for this assessed index
scoring, which is in Table 2-2 above. It was extrapolated to cover all scores between 1 and 5.
The scoring follows the linear regression of y = 0.2x + 0.4 (where x is the scoring, and y is the
resulting improvement rate). Figure 2-2 can be utilized to interpret intermediate scores (that are
in between 1 and 5) to obtain how much faster or slower the metric value improvement is based
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Technology and Cost
on the technical factor scoring of the fuel burn reduction prospect index. 100 percent (or a score
of 3) indicates that the pace of metric value improvement will continue at 100 percent of the
estimated current rate of reduction (i.e., rate higher than 100% means larger of reduction and rate
lower than 100% means vice versa). Furthermore, a score of 3 means that the continuous annual
metric value improvement rate for the short- and mid-term methodology remains the same for
the long-term methodology or timeframe. A score of 2 means that the continuous annual metric
value improvement rate decelerates (or decreases) for the long-term methodology, and a score of
4 means that the rate accelerates (or increases).
Scoring
Figure 2-2 Graphical Form of Metric Value Index Scoring
2.2.2.4 Example for Long-Term Metric Value Forecast
An example of an overall fuel burn reduction prospect index for a single aisle airplane type is
provided below in Table 2-3.21 Also, examples of fuel burn reduction prospect indexes for the
other airplane categories are shown below in Table 2-4.
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Technology and Cost
Table 2-3 Single Aisle Example for Fuel Burn Reduction Prospect Index
Single Aisle
Technical Factors:
Effectiveness in
reducing fuel burn
(1-5) [40%]
Likelihood of
implementation in
new technology
(1-5) [20%]
Level of Research
Effort Required
(l-5)xvii [40%]
Fuel Burn
Reduction Prospect
Index
Weight
N/A
N/A
N/A
N/A
Sealing
1
2
4
2.4
Propulsive
3
3
2
2.6
efficiency




Thermal efficiency
3
3
2
2.6
Noise reduction
1
2
3
2
Reduced cooling
3
3
3
3
Reduced power
3
3
3
3
extraction




Reduced thermal
3
3
3
3
management




Induced drag
5
4
1
3.2
reduction




Friction drag
5
4
1
3.2
reduction




Overall Fuel Burn 2.8
Reduction Prospect
Index:
For single aisle, it was projected that there will be a new clean sheet design that will have
substantial aerodynamics improvement, which will reduce drag, and it will have the latest engine
technologies. Thus, there is plenty of potential for the scoring dimensions of fuel burn
effectiveness and likelihood of implementation (favorable scoring in these dimensions).
However, due to the efforts required, there will be risks related to attaining the improvement.
This reasoning led to an overall fuel burn reduction prospect indexxvm that is a little decelerated
from a technical perspective.
xvn For Level of Research Effort, 5 is the least amount of effort needed (more favorable) and 1 is the most amount of
effort needed (less favorable).
xvm As described earlier, the fuel burn reduction prospect index is a projected ranking of the feasibility and readiness
of technologies (for reducing fuel burn) to be implemented for 2030 and later. There are three main steps to
determine the fuel burn reduction prospect index. First, the technology factors that mainly contribute to fuel burn
were identified. These factors included the following engine and airframe technologies as described below:
(Engine) sealing, propulsive efficiency, thermal efficiency, reduced cooling, and reduced power extraction and
(Airframe) induced drag reduction and friction drag reduction. Second, each of the technology factors were
scored on the following three scoring dimensions that will drive the overall fuel burn reduction effectiveness in
the outbound forecast years: effectiveness of technology in reducing fuel burn, likelihood of technology
implementation, and level of research effort required. Third, the scoring of each of the technical factors on the
three dimensions were averaged to derive an overall fuel burn reduction prospect index.
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Table 2-4 Other Airplane Category Examples of Fuel Burn Reduction Prospect Index
Technical Factors:
Large
Quad
Large Twin
Aisle
Small Twin
Aisle
Single
Aisle
Regional
Jet
Turboprop
Large
BGA
Small
BGA
Weight
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Sealing
2.8
2.8
2.8
2.4
2.4
2.2
2.2
1.8
Propulsive efficiency
2.6
2.6
2.6
2.6
2.6
1.6
1.6
1.6
Thermal efficiency
2.6
2.6
2.6
2.6
2.6
1.6
1.6
1.6
Reduced cooling
3.4
3
3
3
3
2.4
2.4
2.4
Reduced power
extraction
3.4
3
3
3
3
2.4
2.4
2
Reduced thermal
management
3.4
3
3
3
3
2.4
2.4
2.4
Induced drag
reduction
3.2
3.2
3.2
3.2
3.6
3
3
3
Friction drag
reduction
3.2
3.2
3.2
3.2
3.6
3
3
3
Profile drag
reduction
2.4
2.4
2.4
2
2
1.8
1.8
1.4
Fuel Burn Reduction
Prospect Index
3
2.9
2.9
2.8
2.9
2.3
2.3
2.1
However, we recognized that the single aisle market is expected to be thriving in the long-
term based on more point-to-point travel from more fuel-efficient engines, as described earlier.
Thus, it is projected that the market driver index for single aisle is quite favorable with a scoring
of 5, since manufacturers are anticipated to concentrate their research efforts on this market.
Combining the fuel burn reduction prospect index and the market driver index, the resulting
metric value improvement acceleration index is 3.56 as provided in Table 2-5 below.
Table 2-5 Single Aisle Example for Metric Value Improvement Acceleration Index
Fuel Burn Reduction Prospect
Index [65%]
Market Driver Index
[35%]
Metric Value Improvement Acceleration
Index
2.78
5
3.56
This 3.56 score shows that the single aisle metric value improvement will be accelerated
faster compared to an extrapolated short/mid-term metric value improvement rate. With the
linear regression that a 1 score represents 60 percent annual metric value decelerated
improvement rate and a 5 score represents a 140 percent annual metric value accelerated
improvement rate, a score of 3.56 represents that single aisle will annually accelerate at a rate of
111 percent. This annual metric value accelerated improvement rate was integrated into the
extrapolated short/mid-term metric value forecast for the appropriate airplane models.
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2.2.2.5 Long-Term Replacement Airplane Analysis (2030-2040)
In addition to the long-term metric value forecast, the potential long-term replacement
airplanesxlx were analyzed according to the following factors: historical airplane design
transitions, metric value improvement step-down (metric value improvements of 10-20 percent)
per airplane generation, and timing of airplane design transition.™'22 Based on these factors, the
potential long-term airplane replacements that current/new generation airplanes will transition
into were developed for the latter end of the forecast years. The potential airplane replacements
were identified as provided below in Table 2-6.XX1
Table 2-6 Long-Term Potential Replacement Airplanes
Market
Category
Airplane
Type
2030-2040 Replacement
Estimated
EISa
MV Improvement
Estimate
Uncertainty
Band (+/-)
Air Transport
Large Quad
No direct replacement.
N/A
N/A
N/A
Air Transport
Large Twin
Aisle
777X
beyond
2040
N/A
N/A
Air Transport
Small Twin
Aisle
Re-wing or re-engine small twin
aisle
late 2030
~15%
3%
Air Transport
Single Aisle
Clean sheet airplane
early 2030
~20%
4%
Air Transport
Regional Jet
Re-wing regional jet
early 2030
~10%
2%
Air Transport
Turboprop
Re-wing or re-engine turboprop
airplane
early 2030
-10%
2%
Air Transport
Freighter
A330neo or 777X freighter
late 2020
N/A
N/A
BGAb
Large BGA
Re-wing or re-engine large
business jet
early 2030
-10%
2%
BGA
Small BGA
Re-wing or re-engine small
business jet
early 2030
-10%
2%
a.	Entry into service (EIS)
b.	BGA means business and general aviation airplane.
The detailed results of the long-term replacement and reference airplane assessment is in the
Technology Response Database that accompanies the 2018 ICF updated analysis, which is
located in the docket for this proposed rulemaking.™1 In the Technology Response Database,
XD! The term, "replacement airplane," in the long-term methodology means airplane that are projected to replace in-
production airplane and current in-development (or on order airplane) that are expected to go out of production in
the 2030-2040 timeframe. For some airplane categories, ICF identified specific airplane to replace airplane (e.g.,
777X for Large Twin Aisle category), and for most categories ICF identified a generic airplane (e.g., Clean sheet
airplane for Single Aisle category and re-wing or re-engine small twin aisle for Small Twin Aisle category).
xx Every 15 to 25 years after entry into service, airplane models normally incur major redesigns that are motivated
by aerodynamics or engine efficiency improvements that substantially reduce fuel burn. These major re-designs
normally generate significant reductions in fuel burn and MV - 10 percent to 20 percent compared to the previous
generation they replace, depending on the type of redesign. There are three types of major airplane redesigns:
redesigned engines (re-engine), redesigned wings (re-wing), or clean sheet development.
XX1 This table shows historical examples of major re-design improvements that have been achieved by airplane
manufacturers. Clean sheet re-designs have historically produced about 20+ percent, re-wing have historically
yielded about 15 to 20 percent, while re-engine have historically accomplished about 10 to 15 percent.
xxn ICF, 2018, Airplane CO2 Cost and Technology Refresh and Industry Characterization, EPA Contract Number
EP-C-16-020, September 30, 2018. Technology Response Database that accompanies this report provides these
detailed results of the long-term replacement and reference airplane assessment.
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the long-term replacement airplanes for all in-production and in-development airplane models
(models covered by the MTOM thresholds of the proposed standard) were evaluated, and metric
values for these long-term replacement airplanes were projected based on the available metric
values of reference airplanes,™11 which were grouped by airplane type and manufacturer.
Also, uncertainty bands in determining the metric value improvement estimates were
provided for the long-term replacement and reference airplane assessment. These uncertainty
bands differ by the magnitude of design improvement expected by airplane type. The more
challenging the design improvement, the higher the uncertainty band. For example, designing a
clean sheet airplane will result in a greater potential metric value improvement, but there are
more risks related to attaining the design improvement; therefore, a higher uncertainty band was
estimated. In contrast, a re-engine design improvement has less risk related to achieving the
improvement, and thus, a lower uncertainty band was estimated.
Table 2-1 above provides the results of the analysis of metric value reduction by airplane
variant for the years 2030 and 2040 (the 2030-2040 timeframe) using the long-term methodology
and years 2015, 2018, 2020, 2023, and 2028 (the 2015-2029 timeframe) using the short- and
mid-term methodology, which is described earlier in section 2.2.1.
2.3 Technologies
ICF identified and analyzed about seventy different airframe and engine technologies for fuel
burn reductions, as shown in Table 2-7 and Table 2-8. These technologies are mainly for the
short- and mid-term methodology, years 2015-2029, since the effective dates for the proposed
standards would be within this time frame: 2020 (or 2023 for airplanes with less than 19 seats)
for new type design airplanes and 2028 for in-production airplanes. Further details on these
technologies are presented in the appendix of the 2018 ICF updated analysis. Although weight-
reducing technologies affect fuel burn in-use, they do not affect the metric value for the proposed
GHG standards.XX1V Thus, ICF's assessment of weight-reducing technologies was not included in
this proposed rule, which excluded about one-third of the technologies evaluated by ICF for fuel
burn reductions. Therefore, based on the methodology described earlier in section 2.2.1, ICF
utilized a subset of the about fifty aerodynamic and engine technologies to account for the
improvements to the metric value for the proposed standards (for in-production and in-
development airplanesxxv).
The 2018 ICF updated analysis considered a number of technologies incorporated on
airplanes that had entered service since the initial 2015 analysis. Thus, there are actual service
xxm Reference airplane means an existing in-production airplane or in-development airplane that is expected to go
out of production in 2030-2040 timeframe (and which will have a replacement airplane take its place in the fleet
in the long-term).
XX1V The metric value does not directly reward weight reduction technologies because such technologies are also used
to allow for increases in payload, equipage, and fuel load (this is the case for incorporating weight reduction
technologies to in-production airplanes, but it may not be the case for new type design airplanes). Thus,
reductions in empty weight can be canceled out or diminished by increases in payload, fuel, or both; and, this
varies by operation. Empty weight refers to operating empty weight. It is the basic weight of an airplane
including the crew, all fluids necessary for operation such as engine oil, engine coolant, water, unusable fuel and
all operator items and equipment required for flight but excluding usable fuel and the payload.
xxv Airplanes that are currently in-development but will be in production by the applicability dates. These could be
new type design or redesigned airplanes.
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Technology and Cost
histories to consider now, especially for natural and hybrid laminar flow. Also, the recent
completion of some major design changes (i.e., re-engine, re-wing) were assessed.
Table 2-7 Airframe and Systems Technologies
Airframe Technologies
Aerodynamic
Structural
Systems
• Adaptive Trailing Edge
• Advanced Metals
• Lightweight Lightening Strike
• Advanced Wingtip Devices
• Increased Composite
Protection
• Variable Camber Trailing Edge
Application
• More Electric Systems
• Re-Wing (non-retrofittable)
• Advanced Composites (non-
• On demand Environmental
• Riblet Coatings
retrofittable)
Control Systems
• Laminar Flow Control
• Re-Wing (non-retrofittable)
• Fuel cell Auxiliary Power Unit
• Natural and Hybrid
• Advanced Configurations (non-
(APU)
• Nacelle, Empennage, and Wing
retrofittable)
• Light interior
• Advanced Configurations (non-
• Titanium Landing Gear
• Fly By Wire
retrofittable)
• Lightweight Paint / Surface
• Carbon brakes
• Gap Reductions
Treatment
• Zonal Drying
• Aft Body Redesign
•
• Control Surface
• Light Profile

•
Table 2-8 Engine Technologies

Engine Technologies

Materials
Architecture
Systems
• Titanium Aluminide (TiAl)
• Ultra High By Pass(UHBP)
• Bleedless engines
turbine airfoils
engine (above 10 Bypass Ratio
• Electric engine start
• TiAl compressor airfoils
(BPR))
• High Pressure Compressor
• Ceramic-matrix composites
• UHBP (above 20 BPR)
(HPC) mod. Clearance control
(CMC) turbine shrouds/ Outer
• Open rotor
• Turbine mod. Clearance
Air Seal (OAS)
• Variable cycle
control
• CMC High Pressure Turbine
• Intercooled compressors
• Clearance control w/ feedback
(HPT) blades/ vanes
• Integrated propulsion system
• High Pressure (HP)/LP power
• CMC Low Pressure (LP) blades/
• Lightweight component fab
extraction sharing
vanes
techniques
• High eff. Oil/air cooler
• Organic Matrix Composite
• Reduced hub-tip ratio fan
• Recuperative exhaust
(OMC) fan blades
• Fan drive gear

• OMC case
• Next gen load sharing

• CMC exhaust nozzle
architecture

• Ceramic bearings


• Turbine coatings


• OMCstator


• OMC comp. cases


Aerodynamics
Sealing
Coating / Cooling
• Next gen engine airfoil designs
• Compressor blisks
• Compressor airfoil coating
• Optimized fan root fairing
• Turbine blisks
• Turbine air cooling air cooling
• Scalloped fan exhaust

• Next gen. turbine airfoil
• Low Pressure Ratio (PR) fan

cooling design
• Low drag inlet/nacelle


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Technology and Cost
Airframe technologies: The airframe technologies that accounted for the improvements to the
metric values from airplanes included aerodynamic technologies that reduce drag. Drag-
reducing technologies included advanced wingtip devices, adaptive trailing edge, aft body
redesign, laminar flow control (hybrid laminar flow control - empennage), riblet coatings, and
environmental control system (ECS) aerodynamics and on-demand ECS scheduling. For the
2018 ICF updated analysis, the technical feasibility projection was increased for riblet coatings
due to recent progress on this technology, and the commercial feasibility was mainly decreased
for hybrid laminar flow control (empennage) due to the decrease in fuel prices.
Engine technologies: Engine manufacturers target improvements to address thrust specific
fuel consumption (TSFC), propulsion system weight reduction, maintenance cost reduction,
performance improvement, or system reliability. Though there are a range of improvement
drivers that can be embodied (including the use of better materials and optimization in engine
architecture), the gas turbine engine technologies that accounted for incremental reductions to
the metric values are mainly driven by improvement in airfoil aerodynamics and sealing
technologies. Airfoil aerodynamics technologies included next generation engine airfoil designs,
and sealing technologies included compressor and turbine blisksXXV1.23 For the 2018 ICF updated
analysis, the fuel burn reduction impact and commercial feasibility were increased for engine
technologies due to recent progress in the technologies listed above. This reflects the
observation that engine manufacturers are constantly improving these technologies, and it seems
to be a high priority for industry to incorporate such engine technology improvements.
Details on the airframe and engine technologies listed above for metric value improvement
are described below in sections 2.3.1 and 2.3.2 and the appendix for Chapter 2. Further details of
these technologies are also provided in the 2018 ICF updated analysis (particularly section VII
Appendices, Appendix 6, Technology Profiles).
2.3.1 Airframe Technologies
2.3.1.1 Advanced Wingtip Devices
Advanced wingtip devices are successful at increasing the lift-to-drag ratio of an airplane,
which improves its performance (including takeoff and climb performance) and reduces fuel
burn. The annual rate of fuel burn improvement is projected to be 3.5 percent for all the airplane
categories. These advanced wingtip devices include winglets (single or split) or span extensions.
Enlarging the span or the vertical extent of the wing reduces the lift-induced drag by spreading
the vorticity, decreasing the adverse impact that this vorticity has on the remainder of the wing.
There are tradeoffs between extending the wing horizontally compared to installing a winglet.
Aerodynamically, a wing horizontal extension is more effective in decreasing the induced drag
compared to an equivalent increase in the vertical extent of the wing. The equivalent horizontal
extension can be made smaller for the same induced drag reduction, and this further reduces the
viscous drag penalty. However, the horizontal extension induces larger bending moments on the
wing and thus results in a heavier wing, which makes it more challenging to integrate on a wing
that has already been designed.
xxvl Blisks means disks and individual blades are manufactured in one piece - blades are not inserted into disk later -
which removes the need for blade roots and disk slots.
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Technology and Cost
2.3.1.2	Adaptive Trailing Edge
The objective of the adaptive trailing edge is to tailor the wing to minimize the drag at
different flight conditions. Instead of using hinged surfaces to modify the shape of the wing,
morphing the wing (or morphing the trailing edge of the wing) changes the shape of the structure
continuously by using piezoelectric materials or by internal mechanisms. (A morphing wing can
change its geometric shape during flight to optimize performance.). The outcome is a smooth
variation in the shape of the wing with no gaps that would otherwise add to the overall drag.
There are two possibilities to implementing the morphing trailing edge: (a) local morphing on
the trailing edge or conventional moving surfaces to augment or replace the conventional
adaptive trailing edge technology or (b) replace all control surfaces with morphing. The latter
possibility would have the advantage of eliminating the drag from gaps, and it enables a finer
control of the spanwise distribution of the trailing edge camber. The annual rate of fuel burn
improvement of this technology is projected to range from 0.5 to 2 percent for the various
airplane categories. However, the small business and general aviation category is projected to
have no fuel burn improvement from this technology (due to technical or economic reasons).
2.3.1.3	Aft Body Redesign
There are possibilities for aerodynamic improvements on the aft body of numerous
contemporary airplanes. The majority of aerodynamic analysis and design effort targets the
wings; however, opportunities for drag reduction on non-lifting parts such as the fuselage have
also become an emphasis of airplane manufacturers. For example, this technology is on the
Boeing 737 MAX.XXVU
For in-production airplanes, it is not practical for airplane manufacturers to conduct a major
redesign of the aft body, but it is possible to make modifications on the existing shape. The area
where the horizontal and vertical tails join the fuselage is especially important for interference
drag, and it is an effective area for redesign. The annual rate of fuel burn improvement of this
technology is projected to range from 1 to 1.3 percent for the various airplane categories.
2.3.1.4	Hybrid Laminar Flow Control - Empennagexxvm
Skin-friction drag is one of the main sources of drag on an airplane, and it typically accounts
for over 50 percent of the total drag at cruise operations. This drag is due to the friction caused
by the boundary layer.XX1X Boundary layers can be either laminar or turbulent, and the former
produce less friction and therefore less drag. Laminar boundary layers are also thinner,
contributing to a reduction in pressure drag as well. Because of the combination of high speed
xxvii "The tail cone will be extended and the section above the elevator thickened to improve steadiness of air flow.
This eliminates the need for vortex generators on the tail. These improvements will result in less drag, giving the
airplane better performance." April 11, 2012. Available at http://www.b737.org.uk/737max.htm (last accessed
March 17, 2020)
xxvm empennage, commonly called the tail assembly, is the rear section of the airplane. Its primary purpose is to
provide stability to the airplane. It includes the horizontal stabilizer and the vertical stabilizer or fin. Available at
http://www.pilotfriend.coni/training/flight training/fxd wing/emp.htm (last accessed March 17, 2020).
XX1X The boundary layer is a thin layer of air flowing over the surface of an airplane wing or airfoil (as well as other
surfaces of the airplane). Available at http://www.pilotfriend.coni/training/flight training/aero/boundary.htm
(last accessed March 20, 2020).
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Technology and Cost
and scale of commercial transport airplanes, the boundary layers on these airplanes are almost
entirely turbulent. It is especially challenging to attain a laminar boundary layer in this flow
regime through passive means, particularly in lifting surfaces that are swept. Even though they
begin as laminar at the leading edges, they will quickly transition to turbulent unless the right
technology is utilized.
Natural laminar flow (NLF) depends exclusively on the careful design of the aerodynamic
shape to delay the transition of the boundary layer from laminar to turbulent as much as possible.
The higher the speed and the longer the dimensions, the more difficult it is to attain.
Furthermore, wing sweep has an adverse effect. Therefore, NLF is currently not feasible on
wings of commercial transports flying at high subsonic speeds.
Yet, recent progress has made it possible to attain NLF for a substantial portion of engine
nacelles, as is the case in the Boeing 787. NLF necessitates particularly tight manufacturing
tolerances and focus on the paint material and thickness. The Boeing 777X will also have
nacelles with NLF.
The boundary layer will ultimately transition from laminar to turbulent when the streamwise
distance is long enough. To increase the extent of laminar flow beyond what is possible through
passive means of NLF, or to ensure laminar flow with an adverse shape or flight condition, it is
possible to use hybrid laminar flow control (HLFC).
HLFC uses suction to delay the transition from laminar to turbulent and, therefore, generate
areas with a laminar boundary layer. This technology was tested for the 787-9 vertical tail.
Typically, the suction is generated by mechanical means and requires a source of power. The
patent filed by Boeing seems to show a system that does not necessitate mechanical power: it
sucks the boundary layer in through tiny holes in the skin to a plenum, or hollow chamber, inside
the leading edge vertical tail that is then connected to an area of lower pressure elsewhere. This
technology decreases the complexity of the system and eliminates the power requirement,
making it commercially more viable. The annual rate of fuel burn improvement of this
technology is projected to range from 0.3 to 2.5 percent for the various airplane categories.
However, as indicated earlier since the initial 2015 ICF analysis, the commercial feasibility of
this technology has reduced — primarily due to the decreased price of jet fuel. Also, based on
Boeing's continued review of this technology for drag reduction for the 787, we found that
because of the current wing shape and several other factors, the technology is not producing as
effective a balance of cost and performance as initially expected.
2.3.1.5 Riblet Coatings
Riblets are a pattern of tiny ridges that are aligned in the direction of the flow. This
technology decreases the turbulence at the surface in the direction perpendicular to the flow,
decreasing the skin friction drag. Although this is a well understood approach of decreasing skin
friction drag, the issues of this technology are the manufacturing cost, the durability in service,
and maintenance. With the rising value of decreasing drag, there is a chance that this technology
would be deployed early in the next decade. The annual rate of fuel burn improvement of this
technology is projected to range from 0.5 to 1.5 percent for the various airplane categories. For
the updates to the technologies in the 2018 ICF updated analysis compared to the initial 2015
36

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Technology and Cost
ICF analysis, Airbus and Lufthansa are already experimenting with shark skin coatings,xxx and
British Airways has conducted a test trial with riblet coatings on the transatlantic route-dedicated
Airbus A318. Thus, as described earlier, for the updates to riblet coatings in the 2018 ICF
updated analysis compared to the initial 2015 ICF analysis, the technical feasibility projection
was increased for this technology due to this recent progress on this technology.
2.3.1.6 ECS Aerodynamics and On-Demand ECS Scheduling
The airplane's environmental control system (ECS) provides air supply, thermal control, and
cabin pressurization for the crew and passengers. In addition, avionics cooling, smoke detection
and fire suppression are normally considered part of an airplane's environmental control system.
The Boeing 787 and Airbus A350 both have aerodynamic and power-saving improvements to
the ECS system. The inlet and outlet ducts to the system's compressor have been optimized to
decrease the pressure drag. Also, on-demand ECS scheduling now enables engines to power the
system only when necessary as opposed to powering it for an entire flight. The annual rate of
fuel burn improvement of this technology is projected to be 0.6 percent for all the airplane
categories.
2.3.2 Engine Technologies
Airplane gas turbine engine manufacturers are continually incorporating technologies into
engines to address TSFC, performance improvement, or system reliability. Engine technologies
include a range of improvements, such as materials (e.g., ceramic matrix composite parts),
architecture (e.g., optimizing thermal efficiency versus propulsive efficiency), airfoil
aerodynamics, sealing (e.g., blade tip clearances), and cooling (i.e., blade cooling to enable
higher operating temperatures). Usually, it is airfoil aerodynamics and sealing technologies that
are applied to engines in new in-production airplanes to improve fuel burn, and it is projected
that the annual rate of fuel burn improvement of these technologies would be 0.2 percent for all
airplane categories (except a 0.1 percent annual rate for turboprops). An airplane gas turbine
engine is a highly integrated set of systems that typically limit the number of modifications that
can be made to a new engine after entry into service.
Furthermore, engine manufacturers regularly produce performance improvement packages
(PIPs) that improve fuel burn, reduce maintenance cost, and/or improve performance —
representative PIPs are shown in Table 2-9. below. A minimum of 0.5 to 1 percent fuel burn
improvement (total) is needed to justify the development and certification costs of PIPs. With
the numerous new engine developments that occurred recently or are ongoing, technologies
developed for new engines (such as LEAP-X and Trent XWB) are being migrated back to prior
versions of existing engines (e.g., technology developed for the Trent 1000 and 700EP was
incorporated into a PIP for the Trent 900). While PIPs will vary from engine to engine,
technologies developed in recent engine programs (e.g., GEnx, Trent 1000/XWB, geared
turbofan (GTF), LEAP-X, etc.) will be incorporated into existing engines.
xxx Shark skin riblet coatings have a structure like the skin texture of sharks. Available at
https://www.trave1and1eisure.coni/air1ines-airports/sharkskin-squid-helping-build-planes (last accessed March 17,
2020).
37

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Technology and Cost
Table 2-9. Representative Engine Performance Improvement Packages
Trent 900
V2500
CFM56-5B / -7B

Trent 900









rfl
iM





Introduction of elliptical leading-
edge modifications throughout
the entire compression system
Improved high- and
intermediate pressure
(HP/IP) compressor
blades and vanes
Improved fan and outlet
guide vanes
Tweaks to the air management
system
New software for electronic engine
control (EEC)
New variable stator vane (VSV)
and bleed valve schedules
High Pressure Compressor (HPC)
•	Improved airfoil technology
•	Improved airfoil surface
finish
•	Controlled leading edge
profile
•	Latest design standards
Re-staggered first row of low
pressure turbine (LPT) vanes
New materials / coatings,
advanced sealing, and airfoil
cooling in the high pressure turbine
(HPT)
HPC kit - improved blade
aerodynamics
HPT blade kit - low shock airfoil
with improved cooling
LPT nozzle kit - improved cooling
Lower NOx combustor
2.4 Technology Application
Based on the short- and mid-term methodology and the resulting expected metric value
improvements described above for airplanes (or business as usual improvements to airplane
metric values in the absence of a standard), the EPA does not project the proposed GHG
standards would cause manufacturers to make technical improvements to their airplanes that
would not have occurred in the absence of the proposed standards. The EPA projects the
manufacturers would meet the proposed standards independent of the EPA standards for the
following reasons (as was described in section VILA of the preamble):
•	Manufacturers have already developed or are developing improved technology in
response to the ICAO standards that match the proposed GHG standards;
•	ICAO decided on the international Airplane C02 Emission Standards, which are
equivalent to the proposed GHG standards, based on proven technology by 2016/2017
that was expected to be available over a sufficient range of in-production and on order
airplanes by approximately 2020. Thus, most or nearly all in-production and on order
airplanes already meet the levels of the proposed standards;
•	It is likely that those few in-production airplane models that do not meet the levels of the
proposed GHG standards are at the end of their production life and are expected to go out
of production in the near term; and
•	These few in-production airplane models anticipated to go out of production are being
replaced or are expected to be replaced by in-development airplane models (airplane
38

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Technology and Cost
models that have recently entered service or will in the next few years) in the near term —
and these in-development models have much improved metric values (which are
expected to meet the proposed standards)compared to the in-production airplane model
they are replacing.
Therefore, a technology response would likely not be necessary for airplane models to meet
the proposed standards. This result confirms that the international Airplane CO2 Emission
Standards are technology-following standards, and that the EPA's proposed GHG standards as
they would apply to in-production and in-development airplane models would also be technology
following.
For the same reasons, a technology response is not necessary for new type design airplanes to
meet the proposed GHG standards. The EPA is currently not aware of a specific model of a new
type design airplane that is expected to enter service after 2020 (no announcements have been
made by airplane manufacturers). Additionally, any new type design airplanes introduced in the
future would have an economic incentive to improve their fuel burn or metric value at the level
of or less than the proposed standard.50™1
2.4.1 Technology Responses
As described above, the proposed standards would likely not require a technology response.
However, it is informative to describe the different steps in our technology response
methodology for the short- and mid-term (for years 2015-2029) in addition to the discussions
above on short- and mid-term methods and technologies. First, we determined the difference in
metric value of an airplane model compared to the stringency levels of stringency scenarios.
Note, Chapter 6 of this Draft TSD describes the three stringency scenarios we analyzed for this
proposed rule, and these three scenarios comprise the proposed standards and two alternatives.
Using PIANO metric valuesxxxu and the metric value reduction forecast, we compared the
projected metric values for each airplane model to the stringency levels of the scenarios in the
year of their effective dates — to estimate the difference between the expected performance of the
airplane model to stringency scenarios. Second, we sorted out from the analysis those airplane
models that would end production before an effective date of a stringency scenario. Third,
airplane models that met the levels of the stringency scenarios were sorted out next, and thus, the
remaining airplane models were those models that did not meet at least one of the stringency
scenarios. Chapter 6 of the Draft TSD discusses the airplane models that do not meet the
stringency scenarios and the impacts associated with these scenarios.
ICF developed supply curves that provide the projected metric value improvement of a given
technology against its estimated non-recurring costs (NRC).24 NRC is described in detail later in
section 2.5. The outcome of the supply curves is a ranking of the incremental technologies by
airplane family, from most cost effective to least cost effective. For determining a technical
response, it was assumed that a manufacturer would invest in and apply the most cost-effective
technologies to start and subsequently continue to the next most cost-effective technology — to
attain the incremental metric value improvements anticipated by the metric value reduction
xxxl There will be new type design airplanes in the future, and we expect these airplanes to meet the proposed
standards. This projected outcome would be the baseline status of airplanes, or it would be the business as usual
status of airplanes without this proposed rule.
xxxu As indicated earlier, baseline metric values were generated using PIANO data.
39

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Technology and Cost
forecast. When the new technology is implemented, there is expected to be a step change in the
metric value reduction - where metric value reductions are achieved all at once (instead of
gradually).
For an example, see Figure 2-3 below (MV improvement percentage versus NRC (Smillion)).
which presents business as usual improvements for the Superjet 100 airplane. From the base
year to an example effective date of standards (2025), the metric value reduction forecast
estimates a given reduction -- 6.25 percent. Yet, to attain that amount of reduction, the
manufacturer would need to incorporate Advanced Wingtip Devices and Engine Technologies
onto the airplane, for a total of 7.7 percent in metric value reductions. Although the smoothed
forecasted reduction shown in the supply curve is 6.25 percent at the example effective date, the
actual reductions are greater since the metric value improvement from the technology is fully
realized when the technology is incorporated onto the airplane. Representative metric value
improvements and their associated non-recurring costs by airplane category are shown in Table
2-10 and Table 2-11 below. Also, the NRC and fuel burn reduction for each technology
described earlier in section 2.3 are provided in the technology profiles in the Appendix of this
chapter. Also, see the Appendix for examples of supply curves by the different airplane
categories.
$1,600
Example: Superjet 100 Incremental Improvement Technology Supply Curve
Gap to scenario t%)

I 2035 irnpuvemert Le«
1
I Adaptive Trading Edge
3 C?*»Vtii Surface - Optimal Control
Lvihs for hanzontal stab trim
| Natural Laminar Flow Central -
Nacrito
3 Gap Hedwatefli- Siao, Spoiler*,
etc.
Aerodyne trie APLI Faring / Aft
body re design
I Other Systems Im prs ana
I ECS Aero and On C-em&nd EC'S
Scheduling
I Otfier Aerodynamc improvements
I Redudftg Prc-fiie- of the Light*
3 Engine Technologies
I Advanced wngcp Dtvfces -
Retrofit
		 ^ MV Supply Curve Line
6%	8%	10%
Metric Value Improvement
Accelerated technology insertion analysis methodology:
Q For a given future year, a manufacturer's technology insertion is assumed to have progressed up the supply curve
0 Implementation of those technologies may yield a greater MV reduction than the smoothed MV forecast implies
^ Remaining more expensive technologies are the ones eligible for accelerated investment
Figure 2-3. Example Supply Curve
The approach below was used to develop a projected business as usual metric value
improvement in the form of a smoothed forecast for each airplane type that would need a
technology response (to comply with a stringency scenario):
40

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Technology and Cost
1.	For a given future year, a manufacturer's technology insertion was assumed to have moved
up the supply curve (i.e., technologies with the largest improvement and most economical
cost are implemented first). Thus, these most economical technologies would have already
been applied by the stringency year and will not be available for future investment.
2.	The smoothed forecasted incremental metric value improvement is overlaid by the stringency
year on an airplane model's distinct supply-curve. From this overlay, the most economical
technologies were identified that would already have been applied by the stringency year.
3.	The remaining technologies not yet applied are available for accelerated investment when a
technology response is necessary. For each in-scope airplane model, these technology
responses were assessed using PIANO data.
2.4.2 One Percent Additional Design Margin for Technology Response
In the event where a technology response was modeled, we assumed that a manufacturer
would need to provide an additional 1 percent design margin beyond the level needed to achieve
the standard. This design margin would ensure the technology response attains the level of the
standard, where in reality fuel burn reductions for a given technology response can be variable.
2.5 Estimated Costs
This section provides the elements of the cost analysis for technology improvements,
including non-recurring costs (NRC), certification costs, and recurring costs. As described,
above, the EPA does not anticipate new technology responses due to the proposed GHG
standards, and, consequently, we do not expect any costs (technology costs) from the proposed
GHG standards — except limited costs associated with our annual reporting requirement.
However, it is informative to describe the characteristics of these different cost elements. While
recognizing that the proposed GHG rule does not have NRC, certification costs, or recurring
costs, it is informative to describe the elements of these costs (particularly to provide context for
the NRC of an alternative described later in Chapter 6).
2.5.1 Non-Recurring Costs
Non-recurring cost (NRC) consists of the cost of engineering and integration, testing (flight
and ground testing) and tooling, capital equipment, and infrastructure (capital). Engineering and
integration costs include the engineering and research and development (R&D) needed to
progress a technology from its current technology readiness status to a status where it can be
incorporated into a production airframe,50™11 as well as costs for airframe and technology
integration. Testing costs include the fixed costs for test instrumentation, infrastructure, and
project management and variable costsXXX1V associated with the amount of required flight and
ground testing. Capital costs include the following: (a) tooling necessary to change the
production line to support the fuel burn improvement, (b) modifications to plant, property, and
equipment, and (c) other items such as information technology and supply chain systems.
As described earlier for the technology improvements and responses, ICF conducted a
detailed literature search, conducted a number of interviews with industry leaders, and did its
xxxm See description of technology readiness levels (TRLs) earlier in section 2.1.
XXX1V Variable costs are flight and ground testing costs that scale with the amount of time used for testing. For
example, fuel costs and crew/test engineer salaries scale with the time for flight and ground testing.
41

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Technology and Cost
own modeling to estimate the NRC of making modifications to in-production airplanes. The
EPA used the information gathered by ICF for assessing the cost of individual technologies,
which were used to build up NRC for incremental improvements (a bottom-up approach). These
improvements would be for 0 to 10 percent improvements in the airplane fuel efficiency metric
value, and this magnitude of improvements is typical for in-production airplanes (the focus of
our analysis). In the initial 2015 ICF analysis, ICF developed NRC estimates for technology
improvements to in-production airplanes, and in the 2018 ICF updated analysis these estimates
have been brought up to date. The technologies available to make improvements to airplanes are
described earlier in section 2.3.
The methodology for the development of the NRC for in-production airplanes consisted of
five steps. First, technologies were categorized either as minor PIPs with 0 to 2 percent (or less
than 2 percent) fuel burn improvements or as larger incremental updates with 2 to 10 percent
improvements. Minor PIPs were aerodynamic cleanups (e.g., redesigned fairings) and other fuel
burn improvements where frequently compliance is attained by analysis and without dedicated
flight test airplanes.xxxv Large incremental updates were aerodynamic or structural
improvements (e.g., winglets) that reduce fuel burn, where compliance would include flight test
programs - typically with production airplanes. Second, the components of non-recurring costs
were identified (e.g., engineering and integration costs), as described earlier. Third, baseline
non-recurring cost component proportions were developed by incremental technology category
for single-aisle airplanes. Fourth, the baseline NRC components for a single-aisle airplane were
scaled to the other airplane size categories. Fifth, we compiled technology supply curves by
airplane model. Appendices A and B of this Chapter 2 and the 2018 ICF updated analysis
provide a more detailed description of this NRC methodology for technology improvements and
results.25
2.5.1.1 Non-Recurring Costs Component Proportions
For single aisle airplane technologies, the proportions of the various NRC components differ
whether it is an airframe or engine technology.26 Also, for airframe technologies, this proportion
varies whether the technology is a minor PIP or a large incremental update. Figure 2-4 below
shows the NRC component proportions for the category of single aisle airplanes. Generally, for
engine improvements, flight and ground testing is a substantial portion of the NRC. However,
for minor airframe PIPs, the NRC is mainly engineering costs. Since minor airframe PIPs
typically do not necessitate dedicated flight testing, NRC is focused on the engineering design
and analysis required to analytically show compliance for PIPs. Large incremental updates for
airframes would necessitate a flight test program, and thus, a substantial fraction of the NRC
would be from this testing.
xxxv Compliance for minor PIPs would typically include only minor ground, wind tunnel, and flight tests (with the
analysis).
42

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Technology and Cost
Engrg
. 55%
Engrg
, 85%
Airframe
Large
Airframe
Minor PIP
Engrg = Engineering and Integration PIP = performance improvement package
Figure 2-4. Single Aisle Category Non-Recurring Cost Component Proportions
2.5.1.2 Non-Recurring Cost Scaling Factors
Non-recurring cost components for metric value improvement scale differently with airplane
size — or maximum takeoff mass; therefore, different scaling factors were used. Engineering and
integration costs and capital costs are not strongly correlated with airplane size, and thus,
airplane realized sale price was used to scale this component. Flight and ground testing scales
with airplane operating costs; therefore, block hour5"™ average operating costs were used to
scale with this component. Table 2-10 below shows estimates of these scaling sources.
Engineering and capital scale by 15 percent of the differential in average realized sale price,
with the single aisle airplane category as the baseline.xxxvu Testing scales with 100 percent of the
operating cost differential, using the single aisle airplane category as the baseline. This results in
factors that scale the cost components for the baseline of the single aisle airplane category to the
other airplane categories, as shown in Table 2-11.27 Using these scaling factors, NRC was
estimated for technologies for each of the airplane categories. (The basic premise is that we
believe that the larger the airplane, the more expensive the engineering and integration cost
would be. Anchoring single aisle airplane as the base index for engineering and integration, as
an example, we then would extrapolate the small twin aisle engineering and integration cost
index by airplane realized price. See example calculation below.)
xxxvi 3iock hour means the time from when the airplane door closes at departure until the airplane door opens upon
arrival (for a given flight).
xxxvu ¦j'q derive the 15 percent scaling factor for engineering and integration costs, we conducted interviews with
market experts to confirm the appropriate factors for engineering and integration — and that engineering and
integration cost does not scale linearly with airplane value (or realized sale price).
43

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Technology and Cost
Table 2-10 - Non-Recurring Cost Component Scaling Factor Sources
Aircraft
Category
Average Realized
Sale Price
Avg Operating Cost
($/E3lock Hour)
Smalt BGA
$10M
$1,340
Large 8GA
$40M
52,668
Turboprop
$25M
$2,016
Regional Jet
$30 M
$2,688
Single Aisle
S45M
$4,538
Small Twin
Aisle
S130M
$8,143
Large Twin
Aisle
S165M
$10,500
Very Large
Aircraft
S195M
$14,449
Table 2-11 - Non-Recurring Cost Component Scaling Factors
Aircraft
Category
Engineering &
Integration Cost
Flight & Ground Test
Tooling, Capital
Equipment, &
Infrastructure
Small BGA
0.88
0.30
0.88
Large BGA
0.98
0.59
0.98
Turboprop
0.93
0.44
0,93
Regional Jet
0.95
0.59
0.95
Single Aisle
1
1,00
1
Small Twin
Aisle
1,28
1.79
1.28
Large TWin
Aisle
1.40
2.31
1.40
Very Largo
Aircraft
1.50
3.18
1.50
Below is an example calculation of the engineering and integration cost.
We assumed a representative realized price of:
•	Single aisle: $45M
•	Small twin aisle: $130VI
•	Large twin aisle: S165M
44

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Technology and Cost
We then scale the engineering and integration cost by 15 percent of the differential™™1" in
average realized prices.
•	Small twin aisle: 1+15%($130M-$45M)/$45M= 1.28
•	Large twin aisle: 1+15%($165M-$45M)/$45M=1.40
For all large incremental updates (2 to 10 percent improvements), it was assumed that there
would be a minimum $5 million (M) fixed cost, and this fixed cost was used for all incremental
upgrades (which meant the same amount of minimum fixed cost regardless of technology or
airplane category). This minimum fixed cost is for a manufacturer's overhead of basic program
management that comes with any degree of improvement
For an example of the use of the NRC scaling factors by airplane category, see Figure 2-5
below that represents winglets -- which are a large incremental update. For the single aisle
airplane baseline, the total NRC is comprised of the following components: 3 percent baseline
fixed, 52 percent engineering and integration, 40 percent testing, and 5 percent capital. For this
example, an NRC of $173 million was used for the category of single aisle airplanes. With this
baseline, the cost component breakdown provided earlier in Table 2-10 separated the total NRC
into the different components.28
SM NRC
$450
$400
$350
$300
$250
$200
$150
$100
$50
$0
Turboprop Regional Jet Single Aisle Small Twin Large Twin Very Large
Aiste	Aisle Aircraft
Figure 2-5. Example Non-Recurring Cost Scaling by Airplane Category - Large Incremental Update
xxxvm ¦pkg approach 0f scaling the engineering and integration from the single aisle category to the other airplane
categories using the 15% differential in average realized prices was developed by ICF, based on their data
sources. As described earlier in this chapter, the data sources for the 2018 ICF updated analysis are detailed in
section II. 1.2 of this ICF analysis (or this ICF report). These data sources include ICF's broad and thorough
market interview program (with key individuals in the aviation industry and university/research organizations),
research, and knowledge gained through past work on in-depth aviation cost models.
$375






$257


S173



$128
$140






















iloofing. Caprtal
Equip, &
Infrastructure
i Flight & Ground
Test
i Engineering &
Integration
i Minimum Fixed
Cost
45

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Technology and Cost
2.5.2 Comparing the EPA NRC to ICAO/CAEP NRC for International Airplane CO2
Emission Standards
As described earlier, ICAO's CAEP conducted an analysis of the international Airplane CO2
Emission Standards, which were agreed to at CAEP in February 2016, and this analysis included
an assessment of the NRC. For purposes of showing all the available data on NRC for the
standard, we are providing a comparison of the NRC costs in our analysis to the NRC costs in
the CAEP analysis. Note that CAEP published a report of their meeting in February 2016, and
Appendix C of this meeting report is a summary of the methods and results - for costs and
emission reductions — from the CAEP analysis.29 Some of the information used in the CAEP
analysis is not available in this report and thus to the public, due to commercial sensitivities.
Any information from the CAEP analysis that is not in the report of the February 2016 CAEP
meeting cannot be shared outside of CAEP, and thus, it will not be provided in this EPA Draft
TSD.
As described in the 2015 ANPR, CAEP developed an approach for estimating NRC that was a
function of an airplane's MTOM and the required metric value improvement (percent metric
value improvement for a technology response), which CAEP termed the Continuous
Modification Status (CMS) approach. Based on past practice, industry provided estimates for
developing clean sheet designs and redesigns, only including high level information that has
been made available to the public. As a result, this was a top-down estimate which included all
airplane development costs (type certification, noise, in-flight entertainment, etc.), not just those
costs for CO2 improvements.
Since the initial dataset provided by industry only included major changes (or major
improvements), the EPA supplemented this dataset with an estimate of C02-only improvements,
which was a bottom-up estimate. These changes would be much smaller, on the order of a few
percent, and could be applied to in-production airplanes. As described earlier, we contracted
with ICF to develop an estimate of the cost to modify in production airplanes to comply with
CO2 standards (the initial 2015 ICF analysis).30 The results from this 2015 ICF peer-reviewed
study (for small changes) were then combined with inputs from the industry and the other CAEP
participants (for large changes) to develop the CO2 technology response and cost estimation. For
the cost estimation, the CAEP combined the two different methodologies to develop the final
cost surface.XXX1X Due to this combination of these methods for CAEP's CMS approach, CAEP
indicated that the accuracy of the costs generated by the NRC methodology is representative and
considered fit for purpose.
As described above, CAEP's top-down approach in NRC for large changes would be seen in
redesigns or new type designs. For redesigns that result in new series of an established model,
these types of changes may include redesigned wings, new engine options, longer fuselages,
improved aerodynamics, or reduced weight. When making significant design changes to an
airplane, many other changes and updates get wrapped into the process that do not affect the CO2
emissions of the airplane, and redesigns may not have been spurred solely by changes to fuel
efficiency (CO2 reductions). This confluence of changes led CAEP to agree that it was
reasonable to use the full development cost for a new type design or redesign for significant
xxxix two dgtgsets were merged together, and a single cost surface was then generated to calculate the cost to
modify any airplane based on the MTOM, and percent metric value change needed.
46

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Technology and Cost
design changes. Total costs for past projects were used to estimate non-recurring cost for the
CAEP analysis. This type of airplane improvement/development program has historically
ranged approximately from $ 1 to $ 15 billion depending on the size of the airplane and scope of
the improvements desired.
As discussed above, CAEP's bottom-up approach was used to model smaller incremental
metric value changes to airplane design. CAEP agreed that the above top-down approach would
not be the best approach for minor changes or incremental improvements, because the significant
design efforts include many changes that would not be required for smaller CO2 reductions. The
EPA used the information gathered by ICF in their 2015 report to provide input to CAEP on the
cost for individual technologies, and the ICF's information was used to build up CAEP's non-
recurring costs for these incremental improvements (a bottom-up approach). The technologies
available to make incremental improvements to airplanes are wide ranging and airplane specific.
Some examples of technologies are described earlier in section 2.3. As an example, in the initial
2015 analysis, ICF estimated that depending on the additive nature of specific technologies and
the magnitude improvement required, the cost to incrementally improve the Boeing 767 could
range from approximately $230 million to $1.3 billion US dollars (3.5 percent to 11 percent
metric value improvement).31
CAEP's CMS approach was based on the functional form of the NRC surface as provided in
Equation 2-4 below.32 NRC is measured in billions of US Dollars with a 2010 reference year.xl
The NRC surface has been calibrated to generate NRC estimates across a broad range of airplane
sizes or MTOMs (MTOM is the same as MTOW) and metric value improvements. The method
consists of a single cost surface that is a function of metric value improvement and airplane
MTOM.
Equation 2-4 Function of CAEP's NRC Surface
	2-	1 -(	1
^	# Engines } \MJO M-„., J
Reference	Reference	A ire rail
Airframe NRC	Engine NRC	Si/e Solisni
Where coefficients and functions; A, B, C, D and f(AMV) are defined as follows:
NRC Surface Coefficients
ABC
0.188902 3.247077 -0,142274
All coefficients are regressed based on metric value improvement data, except for D, which
along with f(AMV) is represented as a sigmoid function, as shown in Figure 2-6 below. Since
boundaries of metric value improvements differ with MTOM (or MTOW), the cost surface is
driven by a normalized metric value improvement. The normalized metric value improvement is
generated by:xh
xl CAEP's NRC is measured in billions of US Dollars with a 2010 reference year.
xh The Metric Value Improvement Upper and Lower Bounds were airplane specific terms developed by CAEP.
These terms were not discussed, nor were data provided on them, in the publicly available Appendix C of the
February 2016 CAEP meeting report, and thus, they are not described further in this EPA Draft TSD.
47

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Technology and Cost
Equation 2-5 Equation to Calculate AMV
AMV = |MV Improvement\ — MV Improvement Lower Bound
Equation 2-6 Equation to Calculate Normalized MV Improvement
Normalized MV Improvement = x
AMV
MV Improvement Upper Bound - MV Improvement Lower Bound
0.16
0.14
0.12
0.1
2 0.08
0.697-0.5453
D= 0.5453 +	. ...	004	/	0.15
i +e(-2SU-0.3})	,	/	=
0.2	0.4	0.6	0.8	1	0 i
x (Normalized AMV)
1 + e(-2S{x-Q3))
0.4	0.6
x (Normalized AMV)
Figure 2-6. CAEP NRC Surface's Coefficient D (left) and f (AMV) (right) Formulation
Table 2-12 and Table 2-13 below show a comparison of today's NRC results from the EPA
analysis (based on 2018 ICF updated analysis) to the results of the ICAO/CAEP's NRC Surface
(for the CAEP 10 meeting in 2016): NRC ($B) for percent metric value improvement. Table
2-12 and Table 2-13 provide NRC for representative airplanes in each airplane category, ranging
from a percent metric value improvement of 3.5 percent to greater than or equal to 10 percent.
Note that ICAO/CAEP's NRC are a function of MTOM, and nearly all the representative
airplanes and associated airplane categories have different MTOMs, which shows how the
ICAO/CAEP NRC changes with MTOM. The results from the ICAO/CAEP NRC surface are on
average about 170 percent greater compared to EPA's analysis. Table 2-12 indicates that the
results from the CAEP NRC surface are on average about 90 percent greater for small BGA
through single aisle airplane categories, and Table 2-13 shows that the CAEP NRC are on
average 245 percent greater for small twin aisle through large quad categories.
These results are expected for two reasons. First, CAEP's technology responses were based
on technology available in 2016-2017 (or frozen technology 2016-2017) — compared to the
EPA's responses that considered technology available by 2017 and assumed continuous
improvement until 2040 based on the incorporation of these technologies onto airplanes. Also,
ICF considered the end of production of airplanes based on the expected business as usual status
of airplanes. Thus, ICF was able to use the actual effective dates of the proposed standards in
their analysis. Second, the CAEP NRC surface is a combination of the two different
methodologies discussed above, top-down and bottom-up approaches, and today's EPA NRC
results were only based on the bottom-up approach. Including the top-down approach in the
CAEP NRC surface likely adds to the overestimation of the CAEP NRC estimate because it
48

-------
Technology and Cost
includes all airplane development costs (type certification, noise, in-flight entertainment, etc.),
and not just those costs for CO2 improvements.
Table 2-12 Comparison Results of EPA NRC to CAEP NRC Surface ($ Billions) - Part 1
ICF
COit
ICAO
CNA
52S1
!£»
FA1
20001X
ICF
Celt
JOMJ
CL-iiS
ICAO
Global
aoao
ICF
Cast
ICAO
ATI
42-5
ICAO
AN
140
ICF
Cost
ICAO
CM
7«J
ICAO
ERJ
195 E2
ICF
COft
ICAO
A319-
131
ICAO
BUTT
of if-
700
ICF
Cost
ICAO
MI«U
NEO
ICAO
~ 737
0/it~
7MAX
0.10
0 08
0,13
0.10
0,14
0,18
0,10
0.13
0,14
0,10
0,16
0.20
0,20
0,22
O 77
0.20
0,23
0,23
0.20
0,23
0,45
0.30
0.48
0,70
0,20
0.44
0,48
0,30
0,59
0.82
0,40
0,92
0,90
0.40
0,95
0,95

0,23
0.45

0,43
0.71

0.45
0,49

0.61
0.84

0,9*
0.92

0,97
0.97
0.20
0.24
0.45
0.30
0.49
0,72
0,30
0.45
0,49
0,30
0,61
0.15
0,40
0,35
0,93

0.98
0.58

0.25
0.49

0,53
0.78

0.48
0,53

0,66
0.32

1,04
1.02

1,07
1.07

0,25
0.50

0.53
0,78

S.4E
0,53

0.66
0.93
0,50
1,04
1,02
0.50
1,07
1.07

0,28
0,50

0,54
0.80

0.49
0,54

0,67
0.34

1.0S
1.04

1,10
1,10
0,30
0,2§
0,51
0.40
034
0.80
0,30
030
0,5#

0,68
0.95

1,07
1.05

1,10
1.10
0.30
0,28
0.5#

0.58
O.S6

0.53
0.58

0.72
1.02

1.15
1,13

1.19
1,19

0,28
0.55

0.59
0.87

0.54
0,53

0,73
1.M

1.17
1.14

1.20
1.20

0,30
0,57

0.61
0,91

0.56
0,61
0,40
0.76
1.07

1,21
1.19

1,25
1,25

0,31
0,60

0,64
0.95
A *50
0.59
0,64

0.80
1.13

1,27
:

1,31
1,31

0.32
0.61

:
0.95

0.59
? ::

0,3©
1.14

1,28
1.26

1,32
1,32
0,50
0 =11
0.62

0.66
0,98

0,61
0,§§
0,50
0.82
1.16

1.31
1.28

1,35
1,35

0,33
0.63

0.67
0.99

0.62
0,67

0.83
1.18
0,80
1,33
1.30
0.80
1,37
1,37

0,34
0,65

0,63
1.01
0,60
0.63
0,63

0,85
1.20

1,35
1.32

1,33
1,33
0.60
0,35
0.67

0.71
1,04

0.66
0,71

0.87
1.23

1.33
1.36

1,44
1,44
0.80
0,31
0,68
0.60
0,72
1,06
0.70
0.67
0,72
0.60
0,89
_ :.=
1,00
1.41
1.38
1.00
1,46
1,46
49

-------
Technology and Cost
Table 2-13 Comparison Results of EPA NRC to CAEP NRC Surface ($ Billions) - Part 2
ire ifAA
Cost 3ER
Mi* 1,20
ICF ICAO
Cost B787-8
ic*o
B787-
li
ICf
CWSt
ic*e icao
AJ30- B777-
¦Jftt w|ri|
ICAO
ICf A330-
Cost 800-
NEO
ICAO
B777-
«K
ICF
Cost
ICAO ICAO
A380-8 B747 8
0.20
0.70
0.42
1 QQ
1.3o
2.03
2.05
2.Z7
2.28
2.33
2.35
2.54
158
2.68
2.82
2.85
2.91
2.95
3.00
3.10
0.45
i n
£,UL
2.17
2.20
2.43
2.45
2.50
1 CI
£«i3i£.
2.73
2.77
2.88
3.03
3.06
3.13
3.17
3.23
3.33
0.30
1.00
1,00
0.43
2.03
2.09
2.11
2.34
2.35
2,40
2.42
2.62
2,6©
2.76
2.91
2.93
3.00
3.04
3.10
3,13
0.48
2.30
2.37
2.40
2.65
2.67
2,73
2,75
*3 Q.Q
3.03
3.15
3.31
3.34
3,42
3,46
3,53
3,64
0.50 0.44
2.06
1.20 2.11
2.14
2.36
2.38
2.43
2.44
2.65
2.59
2.50
2.94
1 60 2.97
3.04
3.07
3 1 3
.13
3.23
0,54
2.64
2.71
2.75
3.05
3.06
3.14
3.15
3.43
3,48
3.62
3,81
3.85
3.93
3.91
4.06
4,19
1.00
1.10
0.30 0.67
2,80
2,88
1	Q1
3.27
3.29
O.JI/
3.40
3.74
1.20 3.81
2	QQ
*J 8
4.24
4.29
4.41
4.48
4.58
4.76
0,58
-1 77
2.44
2.47
2.75
2.77
2,84
2,88
3.15
3.20
3.35
3.56
3.50
3,71
3.76
4.00
2.5.3 Certification Costs
After the EPA issues the final rulemaking for the proposed GHG standards, the FAA would
issue a rulemaking to enforce compliance to these standards, and any potential certification costs
for the GHG standards would be attributed to the FAA rulemaking. However, it is informative to
discuss certification costs.
As described earlier, manufacturers have already developed or are developing technologies to
respond to ICAO standards that are equivalent to the proposed standards, and they will comply
with the ICAO standards in the absence of U.S. regulations. Also, this proposed rulemaking
would potentially provide for a cost savings to U.S. manufacturers since it would enable them to
domestically certify their airplanes via the subsequent FAA rulemaking instead of having to
certify with foreign certification authorities (which would occur without this EPA rulemaking).
If the proposed GHG standards, which match the ICAO standards, are not adopted in the U.S.,
the U.S. civil airplane manufacturers would have to certify to the ICAO standards at higher costs
because they would have to move their entire certification program(s) to a non-U.S. certification
50

-------
Technology and Cost
authority.xlu Thus, there are no new certification costs for the proposed standards.xllu However,
it is informative to describe the elements of the certification cost, which include obtaining an
airplane, preparing an airplane, performing the flight tests, and processing the data to generate a
certification test report.
Earlier in section 2.5.1, the testing component of the NRC is described as including fixed
costs for test instrumentation, infrastructure, and project management, and this component of the
NRC includes different costs (and expected to be greater costs) compared to the testing costs
related to only certification discussed in this section. The testing included in certification costs is
only for certifying an airplane to the GHG standards, and for an existing in-production airplane
that is non-GHG certificated this means that the manufacturers would need to conduct some
amount of re-testing and pre- and post-test work to show compliance with the GHG standards.
In contrast, the testing component of the NRC includes the full amount of testing to incorporate a
technology improvement into an airplane and is not limited to testing only for purposes of
certification to GHG standards.
The ICAO certification test procedures to demonstrate compliance with the international
Airplane CO2 Emission Standards — incorporated by reference in this proposed rulemaking —
were based on the existing practices of airplane manufacturers to measure airplane fuel burn and
cruise performance.33 Therefore, manufacturers already have airplane test data (or data from
high-speed cruise performance modelling, which they can use to demonstrate compliance with
the international Airplane CO2 Emission Standards). In the absence of the standards, the relevant
CO2 or fuel burn data would be gathered during the typical or usual airplane testing that the
manufacturer regularly conducts for non-GHG standard purposes (e.g., for the overall
development of the airplane and to demonstrate its airworthiness). In addition, such data for new
type design airplanes, where data has not been collected yet, would be gathered in the absence of
a standard. The baseline status for manufacturers is that they likely would have already done the
work needed to certify their airplanes in the absence of the proposed standards. These details
further support the rationale above for there being no certification costs for the proposed
standard.
CAEP assessed the certification costs for the international Airplane CO2 Emission Standards.
The results of CAEP's assessment of certification costs were not described in the summary of the
CAEP analysis,34 and thus, we are unable to share these CAEP results in this EPA Draft TSD.
Nonetheless, the EPA believes there are no certification costs that should be attributed to this
proposed rule, for the reasons described earlier in this section. Also, the EPA is not making any
attempt to quantify the costs associated with certification by the FAA.
2.5.4 Recurring Costs
There would be no recurring costs for the proposed standards; however, it is informative to
describe the components of recurring costs. The components of recurring costs for incorporating
technologies that improve fuel burn would include additional maintenance, material, labor, and
tooling costs. The EPA analysis shows that airplane fuel efficiency improvements typically
xln In addition, European authorities charge fees to airplane manufacturers for the certification of their airplanes, but
FAA does not charge fees for certification.
xlm Due the unprecedented nature of the proposed airplane emission standards providing cost savings to
manufacturers in this manner, we are unable to quantify the amount of these costs savings.
51

-------
Technology and Cost
result in net cost savings through the reduction in the amount of fuel burned. This makes
economic sense because if technologies add significant recurring costs to an airplane, operators
(e.g., airlines) would likely reject these technologies.35
CAEP's analysis for the international Airplane CO2 Emission Standards included an
assessment of the recurring costs.36 CAEP's recurring costs were described as recurring direct
operating costs (DOC) and included the following elements: (a) capital costs (including finance
and depreciation), (b) other-DOC (including crew, maintenance landing and route costs) and (c)
fuel costs. The results of the CAEP analysis showed the fuel savings from the standards would
far outweigh any of the other elements of the recurring costs. Thus, in total the recurring costs
ended up being a cost savings.
2.5.5 Reporting Requirement Costs
As described earlier, there would be limited costs for the proposed annual reporting
requirement for GHG emissions-related information. (See section V.F of the preamble for a
description of the reports.) A total of 10 civil airplane manufacturers would be affected. It is
expected that these manufacturers will already voluntarily report to the ICAO-related CO2
Certification Database (CO2DB). We expect the incremental reporting burden for these
manufacturers to be small because we would be adding only 2 basic reporting categories to those
already requested by the CO2DB. Also, the reporting burden would be small because all the
information we would be requiring will be readily available — since it would be gathered for
non-GHG standard purposes (as noted earlier in section 2.5.3).
We have estimated the annual burden and cost would be about 6 hours and $543 per
manufacturer. With 10 manufacturers submitting reports, the total burden for manufacturers of
this proposed reporting requirement (for three years)xllv would be estimated to be 180 hours, for a
total cost of $16,290.
Nonetheless, the costs of generating a certification test report should not be attributed to this
proposed rule. The FAA is expected to promulgate a rule to enforce compliance to these
standards subsequent to the EPA final rule of these standards, and any potential costs of the
certification would be attributed to this FAA rule.
2.6 Airplane Fuel Savings
As described earlier, manufacturers have already developed or are developing technologies to
respond to ICAO standards which are equivalent to the standards proposed today. Additionally,
they will need to find a way to certify to the ICAO standards even in the absence of U.S.
regulations. As a result, all airplane models (in-production and in-development airplane models)
are expected to be in compliance with the proposed standards by the time they would become
effective. Therefore, there would be no fuel savings from this proposed rulemaking. Chapter 6
of this Draft TSD discusses the fuel savings from an alternative scenario (Scenario 3) we
analyzed, which is different from the proposed standards (Scenario 1) that match the
international standards. (The other alternative scenario (Scenario 2) does not have fuel savings).
xllv Information Collection Requests (ICR) for reporting requirements are renewed triennially.
52

-------
Technology and Cost
CAEP's analysis for the international Airplane CO2 Emission Standards included an
assessment of the fuel savings.xlv First, CAEP provided results for the cumulative CO2
reductions for different effective dates for the 10 stringency options (SOs) assessed. Chapter 6
provides a description of the 10 CAEP stringency options.xlvi The international Airplane CO2
Emission Standards that were ultimately adopted by CAEP for in-production airplanes were
stringency option 7 (S07) for in-production airplanes (for airplanes with MTOMs greater than
60 tonnes) with an effective date of 2028. Because ICAO analyzed the stringency options
relative to a 2016/2017 fixed technology baseline (without continuous improvement and without
considering the expected end of production of airplanes), the ICAO analysis reports CO2
reductions and technology costs for the international standard. ICAO's projected CO2 reductions
from S07 with a 2028 effective date are shown in Figure 2-7 below, and the results indicate
about 350 Megatonnes (Mt) of CO2 reductions (labeled as 2028-Case-l and in negative
Megatonnes by CAEP in Figure 2-7). These reductions are for S07 applying to all covered
airplanes, even though the international standards that were adopted for airplanes less than or
equal to 60 tonnes MTOM are less stringent, S03. Thus, according to CAEP's approach in their
analysis, the CO2 reductions would be less than 350 Mt.
xlvICAO, 2016: Tenth Meeting Committee on Aviation Environmental Protection Report, Doc 10069, CAEP/10,
432 pp, AN/192, Available at: http://www.Lcao.Lnt/publLcatLons/Pages/catalogue.aspx .(last accessed July 11,
2018). The ICAO CAEP/10 report Is found on page 27 of the English EdLtLon 2018 catalog and Is copyright
protected: Order No. 10069. The summary of technological feasibility and cost Information Ls located In
Appendix C (starting on page 5C-1) of this report. Figure 9 of Appendix C shows the cumulative CO2 reductions
for stringency options, and Figure 12 provides the change in cumulative costs (including fuel savings or negative
fuel costs) for the stringency options.
xlvl As described in the 2015 ANPR and later in Chapter 6 (section 6.1.1), for the international Airplane CO2
Emission Standards, CAEP analyzed 10 different SOs for standards of both in-production and new type design
airplanes, comparing airplanes with a similar level of technology on the same stringency level. These stringency
options were generically referred to numerically from " 1" as the least stringent to "10" as the most stringent. The
2015 ANPR described the range of stringency options under consideration at ICAO/CAEP as falling into three
categories as follows: (1) CO2 stringency options that could impact only the oldest, least efficient airplanes in-
production around the world, (2) middle range CO2 stringency options that could impact many airplanes currently
in-production and comprising much of the current operational fleet, and (3) CO2 stringency options that could
impact airplanes that have either just entered production or are in final design phase but will be in-production by
the time the international Airplane CO2 Emission Standards become effective.
53

-------
Technology and Cost
Cumulative C02 (Megatonnes) Relative to the Baseline
SOI
so:
S03
SOI
S05
S06
S07
SOS
S09
SO10
¦ 2020-Case-l
-200
B2023-Case-1
-100
-S00
2020-Case-4c
> 2023-Case-4c
Figure 2-7. CAEP Cumulative CO2 (Megatonnes) Reductions from the Effective Date to 2040xlv"
Also, CAEP characterized these fuel savings as negative fuel costs, as shown in Figure 2-8
below. (Note, the 10 stringency options CAEP analyzed are discussed later in Chapter 6 of this
Draft TSD.) The results of Figure 2-8 show that the international standards (S07) for in-
production airplanes provided about $125 billion in fuel savings (labeled as 2028-Case-l and in
negative 2010$ billions by CAEP in Figure 2-8).xlvm As described earlier, S03 would apply to
xlviiICAO, 2016: Tenth Meeting Committee on Aviation Environmental Protection Report, Doc 10069, CAEP/10,
432 pp, AN/192, Available at: http://www.icao.int/publications/Pages/catalogue.aspx (last accessed July 11,
2018). The ICAO CAEP/10 report is found on page 27 of the English Edition 2018 catalog and is copyright
protected: Order No. 10069. The summary of technological feasibility and cost information is located in
Appendix C (starting on page 5C-1) of this report. On page 5C-13, the cases analyzed by CAEP are defined.
Case 1 is also named the new type design and in-production airplane applicability case - full technology
response/out of production case. Case 1 is the analysis of the ten SOs at the agreed implementation dates (2020
and 2023: and, subsequently additional sensitivity analyses were conducted for 2025 and 2028), using all
technology responses defined by CAEP, and with airplanes assumed to go out of production at the
implementation dates if they cannot be made compliant to a stringency option level. Case 4 is also named the
new type design-only applicability case - alternative response/production case: Case 4 is the analysis of the ten
SOs at the agreed implementation dates for new type design-only applicability using responses informed by
market considerations, since manufacturers would not have a legal requirement to bring in-production types to
levels under a new type design-only standard. Case 4 is a range of response scenarios from a voluntary response
similar to Case 1 to an absence of any response by growth and replacement airplanes. Case 4c is a sub-case of
Case 4, and it is the analysis of the top 33 percent most likely airplane families to respond to a SO (for each of the
ten SOs). Also, the non-compliant families do not respond in Case 4c, but they remain in production.
xlvm CAEP used $3 per gallon of jet fuel in their analysis.
54

-------
Technology and Cost
airplanes less than or equal to 60 tonnes MTOM, and thus, according to CAEP's approach in
their analysis, the fuel savings would be less than $25 billion (in 2010$).
Clia nge in Cumulative Costa (20 ICS Billion;}
S20C
S10C
sc
-S100
-S2C0
-S3C0
-S4C0
2 02 U-C a se-l AIL Ma rkets
SOL
2


SOT

S03
SOS
Fiisl Cc&t
I Capital Cost
a
u
&
v\
ts
o
u
Oth=r-DOC
NRC
¦ AVL
- Total Coot (DOC-AVL+NRC)
Figure 2-8. CAEP Change in Cumulative Costs for 2028 Effective Date*"*'1
For Figure 2-8, the yellow bars represent fuel costs, and since these fuel costs are negative, they are
fuel savings. AVL means owner /operator asset value loss. Other-DOC includes crew, maintenance
landing and route costs.
The primary difference in the results between the EPA and ICAO analyses is due to the
2016/2017 fixed technology baseline (without continuous improvement and without considering
the expected end of production of airplanes) in the CAEP analysis. For a further description of
the rationale on the fuel savings difference in the EPA analysis results and CAEP results, see the
earlier discussion on costs in this chapter. In addition, refer to Chapter 5 that further discusses
the differences between the EPA and CAEP methods and assumptions for modeling emission
reductions and fuel savings.11
xllx The cumulative costs include Total Recurring Direct Operating Costs (DOC), Manufacturer Non-Recurring Costs
(NRC) for Technology Response (TR) and Owner /Operator Asset Value Loss (AVL) from the Implementation
Year to 2040. Fuel Costs (or fuel savings) are shown in the yellow colored bars.
1ICAO/CAEP did not provide cost and cost-effectiveness results for its stringency option 10, and thus, this option
was not analyzed by ICAO/CAEP in the manner the other nine stringency options were analyzed.
11 For example, the EPA assumes the Airbus A380 will stop production before 2030, but CAEP assumes it will be in
production until 2040.
55

-------
Technology and Cost
2.7	Fuel Prices
The jet fuel price is not central to the EPA analysis, nor would it provide substantially
different results. The EPA analysis is based on demonstrated technology by 2017, and the
projected business-as-usual incorporation of this technology on airplanes out to 2040 (continuous
annual improvement). Also, we estimated the end of production of airplanes based on the
expected business as usual status of airplanes. For lower jet fuel prices, older in-production
airplanes would likely be flown longer, and fleet renewal would slow.37 However, as described
later in Chapter 5, we have a sensitivity analysis case that shows the results of extending
production for some airplanes. Also, in Chapter 5, we discuss a sensitivity analysis case without
continuous metric value improvement that shows the effect of less technology application in the
fleet. For higher jet fuel prices, there is typically an increase in new airplane (or redesign)
launches as well as incremental upgrades. However, there were recently numerous redesigns to
airplanes, as well as incremental upgrades, and we believe the prospects for such improvements
will be low in the next 10 to 15 years. In any event, these recent improvements and the case of
higher fuel prices would only ensure the proposed standards would have even less effect (due to
market forces).
2.8	Summary of Benefits and Costs
Should the proposed airplane GHG standards, which match the ICAO Airplane CO2 Emission
Standards, be finalized, all U.S. airplane models (in-production and in-development airplane
models) should be in compliance with the proposed standards, by the time the standards would
become applicable. Therefore, there would only be limited costs from the proposed annual
reporting requirement and no additional benefits from complying with these proposing standards
— beyond the benefits from maintaining consistency or harmonizing with the international
standards. As described earlier in section 2.5.5, the estimated the annual burden and cost from
the proposal annual reporting requirement would be about 6 hours and $543 per manufacturer.
With 10 manufacturers submitting reports, the total estimated burden for manufacturers of this
proposed reporting requirement (for three years) would be estimated to be 180 hours, for a total
cost of $16,290.
56

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Technology and Cost
Appendix A - Airframe Technologies
During the evaluation of MV benefit for each technology, ICF determined a range of
possibilities of the MV benefit improvement for each technology, because the same technology
would provide different levels of MV benefit depending on each airplane size category.
Subsequently, ICF determined where within the boundary the MV improvement is for each
airplane size category. For airplane categories where the technology would not yield much
benefit, it was categorized as (-), and ICF determined the benefit to be at lowest boundary of the
MV benefit improvement range. On the other hand, where the technology would be most
beneficial for the airplane size category, it was categorized as (+), and it was determined the
benefit to be at the highest boundary of the MV benefit improvement range. Finally, airplane
size categories in between were categorized as (=), for which the average of the minimum value
and the maximum value of the MV improvement range was used.
For example, variable camber trailing edge is predicted to produce between 0.5 - 3.0% of MV
improvement. For turboprops and regional jets, we do not expect this technology to provide
significant benefit; therefore, they were categorized as (-), which means 0.5% MV improvement.
For small twin aisle, large twin aisle, and large quad, this technology would provide significant
benefit due to their sizes; therefore, they were categorized as (+), which means a 3.0% MV
improvement. Finally, for single aisle airplane it would only provide moderate benefit;
therefore, it was categorized as (=), which means the average of a 0.5% MV improvement and a
3.0% MV improvement, and this results in a 1.75% MV improvement.
57

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Technology and Cost
Table 2-14 Fuel Burn and Costs Impacts for Advanced Wingtip Devices38'39

Sources
Small BGA
Large BGA
_§ Q
-e s
£ Q
Regional
Jet
Single
Aisle
Small Twin
Large Twin
Large
Quad
Fuel
Burn
•	Blended winglets achieve 3-5% fuel burn
improvements over non-winglet aircraft
•	New winglet technologies, such as split wingtips
and Aviation Partners Boeing "Scimitar" winglets can
yield 1-3% improvement compared to current
generation winglet technologies
•	Winglets on 737MAX will offer 1-1.5% fuel burn
improvement compared to 737NG blended winglets,
depending on results of investigations into natural
laminar flow
=
=
=
=
=
=
=
=
3.5%
3.5%
3.5%
3.5%
3.5%
3.5%
3.5%
3.5%

2015
2018
2020
2023
2028
2030
Commercial
Feasibility
5%
10%
14%
20%
30%
38%
Technical
Feasibility
100%
100%
100%
100%
100%
100%


Estimated Total NRC ($M) by Aircraft Category
Cost
Impact
•	Used publicly available pricing and interview input
to determine price of current technology winglets
•	Assumed next-generation winglets will have 10%
increased price
•	NRC estimated based on interview input and
some scaling relative to aircraft size
•	Advanced wingtip device NRC was used as a data
point to scale other technology NRCs
$98
$124
$111
$121
$150
$222
$264
$325
58

-------
Technology and Cost
Table 2-15 Fuel Burn and Costs Impacts for Adaptive Trailing Edge

Sources
Small BGA
Large BGA
Turbo-prop
Regional Jet
Single Aisle
Small Twin
Large Twin
Large Quad
Fuel
Burn
•	A full variable camber trailing edge would allow
reduced structural weight due to load alleviation, as
well as reduced control sizing and more efficient
cruise configurations
•	Scaled benefit from adaptive trailing edge given
aircraft manufacturer input and ICF analysis
•	Fuel burn reduction mechanism: induced drag
reduction
X
+
-
-
=
+
+
+
0.0%
2.0%
0.5%
0.5%
1.3%
2.0%
2.0%
2.0%

2015
2018
2020
2023
2028
2030
Commercial
Feasibility
0%
0%
4%
10%
15%
17%
Technical
Feasibility
0%
0%
50%
100%
100%
100%


Estimated Total NRC ($M) by Aircraft Category
Cost
Impact
•	Relative scaling "check" to reflect value of
increased fuel savings
•	NRC estimates scaled relatively from known data
points on program NRC scale
$148
$188
$168
$184
$228
$338
$401
$493
59

-------
Technology and Cost
Table 2-16 Fuel Burn and Costs Impacts for Aft Body Redesign

Sources
Small BGA
Large BGA
Turbo-
nrnn
Regional
Jet
Single
Aisle
Small Twin
Large Twin
Large
Quad
Fuel
Burn
• Fuel burn reduction mechanism: induced drag
reduction
-
=
=
=
=
=
=
=
1.0%
1.3%
1.3%
1.3%
1.3%
1.3%
1.3%
1.3%

2015
2018
2020
2023
2028
2030
Commercial
Feasibility
9%
20%
28%
40%
60%
68%
Technical
Feasibility
90%
100%
100%
100%
100%
100%


Estimated Total NRC ($M
by Aircraft Category
Cost
Impact
•	Significant design and production change for an
aircraft program
•	Cost increase data scaled relatively to other
known modification and checked through
interview feedback
•	NRC estimates scaled relatively from known
data points on program NRC scale
•	Significant NRC related to design and changing
production process
$184
$233
$209
$228
$282
$419
$496
$611
Table 2-17 Fuel Burn and Costs Impacts for Hybrid Laminar Flow Control - Empennage

Sources
Small
BGA
Large
BGA
Turbo-
nrnn
Regional
|pt
Single
Aisle
Small
Twin
Large
Twin
Large
Quad
Fuel
Burn
•	Fuel burn reduction mechanism: skin friction
drag reduction
•	Possible issues with practicality (HLFC requires
small ports in aircraft skin that may become
frequently clogged in practice)
-
-
-
-
=
+
+
+
0.3%
0.3%
0.3%
0.3%
1.4%
2.5%
2.5%
2.5%

2015
2018
2020
2023
2028
2030
Commercial
Feasibility
0%
3%
6%
10%
15%
17%
Technical
Feasibility
0%
80%
100%
100%
100%
100%


Estimated Total NRC ($M) by Aircraft Category
Cost
Impact
• NRC estimates scaled relatively from known data
points on program NRC scale
$254
$324
$289
$316
$391
$580
$688
$847
60

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Technology and Cost
Table 2-18 Fuel Burn and Costs Impacts for Riblet Coatings

Sources
Small
BGA
Large
BGA
Turbo-
nrnn
Regional
|pt
Single
Aiclp
Small
Twin
Large
Twin
Large
Quad
Fuel
Burn
•	Not currently in production, but concept
validated
•	Potential issues with increased maintenance and
cleaning costs, and practicality in field
•	Sources for information included publicly
available documents, secondary research, and
confirmation from airframe manufacturer interview
sources (Gubisch)
•	Fuel burn reduction mechanism: skin friction drag
reduction
-
-
-
-
=
+
+
+
0.5%
0.5%
0.5%
0.5%
1.0%
1.5%
1.5%
1.5%

2015
2018
2020
2023
2028
2030
Commercial
Feasibility
0%
5%
13%
25%
35%
51%
Technical
Feasibility
0%
50%
80%
100%
100%
100%


Estimated Total NRC ($M) by Aircraft Category
Cost
Impact
•	Riblet coatings would primarily affect
manufacturing costs, after initial design NRC is
performed to validate concept
•	Estimates from interviews/ICF team consensus
•	Unknown impact on maintenance costs
•	NRC estimates scaled relatively from known data
points on program NRC scale according to ICF team
judgment
$148
$188
$168
$184
$228
$338
$401
$493
61

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Technology and Cost
Table 2-19 Fuel Burn and Costs Impacts for ECS Aerodynamics and On-Demand ECS Scheduling

Sources
Small
BGA
Large
BGA
o Q
-e E
¦2 Q
Regional
Jet
Single
Aisle
Small
Twin
Large
Twin
Large
Quad
Fuel
Burn
• Fuel burn reduction mechanism is drag reduction
(Thomson)
=
=
=
=
=
=
=
=
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%
0.6%

2015
2018
2020
2023
2028
2030
Commercial
Feasibility
8%
20%
28%
40%
60%
68%
Technical
Feasibility
100%
100%
100%
100%
100%
100%


Estimated Total NRC ($M) by Aircraft Category
Cost
Impact
•	Assumed that refining ECS system would result in
minor charges equal to 0.25% of realized aircraft
sale price
•	Changes are mainly from amortized NRC and
additional control electronics
•	NRC estimates scaled relatively from known data
points on program NRC scale *NRC is aerodynamics
and software design engineering
$40
$46
$43
$45
$50
$68
$77
$87
62

-------
Technology and Cost
Appendix B - Engine Technologies
Table 2-20 Fuel Burn and Costs Impacts for Engine Technologies1"'40'41

Sources
Small
BGA
Large
BGA
Turbo-
prop
Regional
Jet
Single
Aisle
Small
Twin
Large
Twin
Large
Quad
Fuel
Burn
•	Main reduction mechanisms are Airfoil
Aerodynamics and Sealing
•	Engine manufacturers typically do not charge
a premium for engine technology improvements
•	Modeled as a fixed percentage per year,
instead of using commercial or technical
probability built up from individual technologies
=
=
-
=
=
=
=
=
0.2%
/yr
0.2%
/yr
0.1%
/yr
0.2%
/yr
0.2%
/yr
0.2%
/yr
0.2%
/yr
0.2%
/yr

2015
2018
2020
2023
2028
2030
Commercial
Feasibility
N/A
N/A
N/A
N/A
N/A
N/A
Technical
Feasibility
N/A
N/A
N/A
N/A
N/A
N/A


Estimated Total NRC ($M) by Aircraft Category
Cost
Impact
•	Engine manufacturers typically do not charge
a premium for engine technology improvements
•	$100M of NRC for every 1% improvement (on
single aisle-sized engines) for TRL 6+
$118
$200
$115
$181
$270
$503
$681
$720
luTRL6 means system/subsystem or true dimensional test equipment validated in a relevant environment.
ICF International, C02 Analysis of C02-Reducing Technologies for Aircraft, Final Report, EPA Contract Number
EP C 12 011, see page 40, March 17, 2015.
63

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Technology and Cost
Appendix C - Example Supply Curves by Airplane Category
Metric value improvement percentage versus estimated non-recurring costs (Smillion):
Composites - Current State
Increased A pp Scat ion
l l Hybrid Laminar Flow Control-
Empennage
i i Gap Reductions- Slats Spoilers,
etc.
Rblet Coat'rigs
i i Other Aerodynamic
Improvements
Aerodynamic APU Fairing / Aft
body redesign
Other Systems Improvements
ECS Aero and On Demand ECS
Scheduling
Reducing Profile of the Lights
i i Engine Technologies
Adv an ced Wingtip Dev t es -
Retrofit
MV Supply Curve Line
$1,600
$1,400
$1,200
$1,000
2%
4%
10%
6%	8%
Metric Value Improvement
Figure 2-9 Example Supply Curve for Small BGA
64

-------
Technology and Cost
$1,S00
$1,600
$1,400
$1,200
$1,000
Rblet Coatings
i i Control Surface- Optimal Control
Laws for horizontafl stab tr im
] Other Aerodynamic
Improvements
] Other Systems Improvements
i i Aerodynamic APU Fairing / Aft
body redesign
Adaptive Trailing Edge
Variable Camber Traling Edge -
Morphing
ECS Aero and On Demand ECS
Scheduling
Reducing Profiie of the Lights
] Engine Technologies
dv arced Wingtip Devtes-
Stroffc
MV Supply Curve Line
8% 10% 12% 14% 16%
Metric Value Improvement
Figure 2-10 Example Supply Curve for Large BGA
$1,600
$1,400
$1,200
$1,000
$800
$600
$400
$200
I AdaptiveTraiing Edge
$o ^

I I Control Surface- Optimal Control
Laws for horizontal stab trim
J-
	,r l i=i
i i Natural Laminar FlowControl-
Nacele
3 Gap Reductions- Slats Spoilers,
etc.
~ Other Aerodynamic
improvements
I Other Systems improvements
^ E
3 Aerodynamic APU Fairing / Aft
body redesign
l ECS Aero and On Demand ECS
Scheduling
I Reducing Profiie of the Lights
~ Engine Technologies
I Advanced Wingtip Devtes-
Retrofit
-A— MV Supply Curve Line
2%
4%
10%
6%	8%
Metric Value Improvement
Figure 2-11 Example Supply Curve for Turboprop
12%
65

-------
Technology and Cost
$1,600
$1,400
$1,200
$1,000
AdaptiveTraiing Edge
i i Control Surface- Optimal Control
Laws for horizontafl stab trim
i i Natural Laminar Flow Control -
Nacelle
Gap Reductions- Slats Spoilers,
etc.
i i Aerodynamic APU Fairing / Aft
body redesign
Other Systems Improvements
ECSAeroandOn Demand ECS
Scheduling
Other Aerodynamic
Improvements
Reducing Profile of the Lights
] Engine Technologies
Advanced Wingtip Devtes-
Retroft
A— MV Supply Curve Line
Metric Value Improvement
Figure 212 Example Supply Curve for Regional Jet
$2,500
$2,000
$1,500
$1,000
$500
rjt
$0

ap

2%
4%
6%
8%
10%
12%
Metric Value Improvement
Figure 2-13 Example Supply Curve for Single Aisle
B Gap Reductions - Siat$ Spoilers,
etc.
i i Other Aerodynamic
Improvements
i i Other Systems Improvements
i i R Id let Coatings
i i Aerodynamic APU Fairing / Aft
body redesign
I AdaptiveTraiing Edge
i Variable Camber Trailing Edge-
Morphing
I ECSAeroandOn Demand ECS
Scheduling
I Reducing Profile of the Lights
] Engine Technologies
I Advanced Wingtip Devizes -
Retrofit
- MV Su pply C urve Line
14%
66

-------
Technology and Cost
$4,000
$3,500
$3,000
$2,500
$2,000
$1,500
$1,000
$500
$0
¦ Adapts elraiSng Edge



i i Composites - Current State
	 Increased Application
i I Gap Reductions - Slats Spoilers,
etc.

i i Hybrid Laminar Flow Control-
Nacelle
i I Other Aerodynamic
Improvements
Other Systems improvements
] Hybrid Laminar Flow Control -
Empennage
I R b let Coat rigs
I Variable Camber Tra3ing Edge -
Morphing
i i Engine Technologies
I Advanced Wingttp Dev tes-
Rdtrofit
MV Supply Curve Line
2% 4% 6%
8% 10% 12% 14% 16% 18%
Metric Value Improvement
Figure 2-14 Example Supply Curve for Small Twin Aisle
$4,500
$4,000
$3,500
$3,000
$2,500
$2,000
$1,500
$1,000
Gap Reductbns- Slats Spoilers,
etc.
i i Hybrid Laminar Flow Control -
Nacele
i i Other Aerodynamic
Improvements
i i Other Systems Improvements
i I Hybrid Lam bar Flow Control -
Empennage
RbtetCoatbgs
Adaptive Trailing Edge
Variable Camber Traiing Edge -
Morphing
Reducing Profile of the Lights
I I Engine Technologies
Advanced Wingtip Devizes-
Retroft
MV Supply Curve Line
4% 6% 8% 10% 12% 14% 16% 18% 20%
Metric Value Improvement
Figure 2-15 Example Supply Curve for Large Twin Aisle
67

-------
Technology and Cost
$6,000
$5,000
$4,000
$3,000
$2,000
$1,000

rf3
I i Aerodynamic APU Fairing / Aft
body redesign
I I Other Aerodynamic
Improvements
I I Other Systems Improvements
i i Hybrid Laminar FIct/y Control -
Empennage
I I Rtolet Coatings
AdaptiveTraiing Edge
I Variable Camber Traiing Edge -
Morphing
I ECS Aero and On Demand ECS
Scheduling
Reducing Profile of the Lights
i i Engine Technologies
2% 4% 6% 8% 10% 12% 14% 16% 18% 20%
Metric Value Improvement
Figure 2-16 Example Supply Curve for Large Quad
I Adv an ced Wingtip Dev t es -
Retrofit
MV Supply Curve Line
68

-------
Technology and Cost
REFERENCES
5ICAO, 2016: Tenth Meeting Committee on Aviation Environmental Protection Report, Doc 10069, CAEP/10, 432
pp, AN/192, Available at: http://www.Lcao.Lnt/publLcatLons/Pages/catalogue.aspx (last accessed March 17, 2020,).
The ICAO CAEP/10 report Is found on page 27 of the English EdLtLon 2020 catalog and Is copyright protected:
Order No. 10069. The summary of technological feasibility and cost Information Ls located In Appendix C (starting
on page 5C-1) of this report.
6ICF, 2018: Aircraft COi Cost and Technology Refresh and Industry Characterization, Final Report, EPA Contract
Number EP-C-16-020, September 30, 2018.
7	ICF International, 2015: CO2 Analysis of CCk-Reducing Technologies for Aircraft, Final Report, EPA Contract
Number EP C 12 011, March 17, 2015.
8	U.S. EPA, 2015: Proposed Finding that Greenhouse Gas Emissions from Aircraft Cause or Contribute to Air
Pollution that May Reasonably Be Anticipated to Endanger Public Health and Welfare and Advance Notice of
Proposed Rulemaking, 80 FR 37758 (July 1, 2015).
9	See Reference #7.
0	See Reference #6.
1	RTI International and EnDyna, Aircraft CO2 Cost and Technology Refresh and Aerospace Industry
Characterization: Peer Review, June 2018, 112 pp.
2	See Reference #5.
3	See Reference #6.
4	See Reference #7.
5	See Reference #6.
6	See Reference #6.
7	See Reference #6.
8	See Reference #6.
9	See Reference #6.
20	See Reference #6.
21	See Reference #6.
22	See Reference #6.
23	MTU Aero Engines, Blisks (blade integrated disks), Available at http://power.mtu.de/engineerLng-and-
manufacturLng/aero-solutLons/parts-manufacturLng/rotatLng-components/blLsks/ (last accessed March 20, 2020).
24	See Reference #6.
25	See Reference #6.
26	See Reference #6.
27	See Reference #6.
28	See Reference #6.
29	See Reference #5.
30	See Reference #7.
31	See Reference #5.
32	See Reference #5.
33	ICAO, 2016: Tenth Meeting Committee on Aviation Environmental Protection Report, Doc 10069, CAEP/10, 432
pp, AN/192, Available at: http://www.Lcao.Lnt/publLcatLons/Pages/catalogue.aspx (last accessed March 20, 2020).
The ICAO CAEP/10 report Is found on page 27 of the English EdLtLon 2020 catalog and Is copyright protected:
Order No. 10069. The summary of technological feasibility and cost information is located in Appendix C (starting
on page 5C-1) of this report.
34	See Reference #5.
35	See Reference #6.
69

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Technology and Cost
36
See
Reference
#5
37
See
Reference
#7
38
See
Reference
#6
39
See
Reference
#7
40
See
Reference
#6
41
See
Reference
#7
70

-------
Test Procedures
Table of Contents
Chapter 3 Test Procedures	72
3.1	CAEP Test Procedure Requirements-Overview	72
3.2	Test Procedures for Airplane GHG Emissions Based on the Consumption of Fuel.... 72
3.2.1	Flight Test Method	72
3.2.1.1	Preflight	72
3.2.1.2	Flight test - A16 §3.2.2	72
3.2.1.3	Test condition stability	73
3.2.1.4	Measurement of SAR	73
3.2.2	Data Validity	73
3.2.2.1 Reference Conditions & Corrections	73
3.2.3	Equivalent procedures	73
3.3	Determination of the Fuel Efficiency Metric Value	73
3.3.1	Airplane Fuel Efficiency Metric	73
3.3.2	Reference Geometric Factor	74
3.4	Application of Rules for New Version of an Existing GHG-Certificated Airplane	75
3.4.1 No Fuel Efficiency Change Threshold for GHG-Certificated Airplanes	76
3.5	Changes for non-GHG Certificated Airplane Types	78
Table of Figures
Figure 4-1 - Regulatory Analysis Flow Chart	82
Figure 4-2 - The Retirement Curve of Narrow-Body Passenger Airplane Based on Ascend fleet data	86
Table of Equations
Equation 3-1 - International CO2 Emissions Metric for airplanes	74
Equation 3-2 - Equation to calculate Specific Air Range of the airplane	74
71

-------
Test Procedures
Chapter 3 Test Procedures
3.1	CAEP Test Procedure Requirements-Overview
Airplane CO2 emissions test procedures were developed at CAEP based on input from
manufacturers and regulators. In general, Specific Air Range (SAR) is measured on an engine
during flight at three test points. These SAR data represent the distance traveled per unit of fuel
burn and are used to determine the international CO2 metric value for the airplane type.
Manufacturers' flight test procedures for calculating fuel burn and cruise performance were used
as a starting point for development. This input was then standardized to create a consistent
procedure for regulatory purposes. Corrections have also been developed to improve data
consistency and interoperability of measurements. CAEP has also developed preliminary
guidance on equivalent procedures that could be used to meet the requirements. These test
procedures and metric are proposed to be adopted as a measure of GHG emissions of airplanes.
3.2	Test Procedures for Airplane GHG Emissions Based on the Consumption of Fuel
All flight tests must be conducted in an approved manner to yield the fuel efficiency metric
value as described in Section 3.3 below. These procedures shall address the entire flight test and
data analysis process from pre-flight actions to post-flight data analysis.
The flight test procedure has been developed based on standard industry practices for
determining airplane fuel burn performance. This has been standardized into a regulatory
framework.
These test procedures and requirements are described in detail in ICAO Annex 16 Volume III
and in ICAO ETM Volume III.
3.2.1 Flight Test Method
3.2.1.1 Preflight
Annex 16 Vol. Ill §3.2.1 describes the pre-flight procedures that shall be approved by the
FAA prior to any certification testing. These requirements include conformity of the airplane to
the type design which is to be certificated, procedures to weigh the airplane before and after
flight testing, and specifying the fuel used must meet ASTM specification D4809-13 along with
when and how to test the fuel.
3.2.1.2Flight test - A16§3.2.2
Flight testing must be conducted in accordance with the requirements outlined in Annex 16
Vol. Ill Appendix 1 §3.2.2 and §3.2.3. The three test points, described in 3.3.1, must be
separated from each other by a minimum of 2 minutes or by a deviation outside of the stability
criteria for test points. It is recommended during the collection of SAR data that:
•	the airplane should be flown at constant pressure altitude and constant heading;
•	the engine thrust/power setting is stable for unaccelerated level flight;
•	the airplane is flown as close as practicable to the reference conditions to minimize
the magnitude of any corrections;
72

-------
Test Procedures
•	there are no changes in trim or engine power/thrust settings, engine stability and
handling bleeds, and electrical and mechanical power extraction (including bleed
flow). Any changes in the use of aeroplane systems that may affect the SAR
measurement should be avoided; and
•	movement of on-board personnel is kept to a minimum.
Flight testing should be conducted over a period of not less than 1 minute.
3.2.1.3	Test condition stability
For SAR measurement data to be valid, the flight test must remain within the tolerances
indicated in Annex 16 Vol. Ill Appendix 1 §3.2.3.
3.2.1.4	Measurement of SAR
The requirements for measurements and data sampling are described in Annex 16 Vol. Ill
Appendix 1 §4 and ETM Vol. Ill §3.1.
3.2.2	Data Validity
Data validity requirements are described in Annex 16 Vol. Ill Appendix 1 §6. The 90%
confidence interval of the data at the three reference masses shall not exceed 1.5% of the SAR
value without approval from the FAA. If clustered data are acquired independently for each of
the three gross mass reference points, the minimum sample size acceptable for each of the three
gross mass SAR values shall be six. Alternatively, SAR data may be collected over a range of
masses. In this case, the minimum sample size shall be 12, and the 90 per cent confidence
interval shall be calculated for the mean regression line through the data.
Further information on how to determine data validity is provided in ETM Vol. Ill §3.3.
3.2.2.1 Reference Conditions & Corrections
Where the flight test data does not match the reference conditions described in Annex 16 Vol.
Ill §2.5 corrections should be made as described in Annex 16 Vol. Ill Appendix 1 §5.2. Potential
corrections include energy, aeroelastics, altitude, apparent gravity, CG position, power extraction
and bleed, deterioration level, fuel spec, Mass Reynolds Number, and Temperature. ETM Vol.
Ill §3.2.2 describes these procedures in detail.
3.2.3	Equivalent procedures
Per Annex 16 Vol. Ill §1.10 equivalent procedures can be used to show compliance to the
ICAO Airplane CO2 Emission Standards with the prior approval of the FAA. ETM Vol. Ill §3.4
provides some initial guidance on procedures that could be used to show compliance with the
standard. These must still be approved by the FAA prior to their use.
3.3 Determination of the Fuel Efficiency Metric Value
3.3.1 Airplane Fuel Efficiency Metric
The metric (shown in Equation 3-1) for the proposed GHG standards (equivalent to ICAO's
airplane CO2 emissions metric) would use fuel efficiency as a measure of GHG emissions from
airplanes.
73

-------
Test Procedures
Equation 3-1 - International CO2 Emissions Metric for airplanes
(sm) /
C02 Emissions Metric =	(RGF)02*
When the international CO2 emissions metric is correlated against airplane mass it has a
positive slope. The international Airplane CO2 Emission Standards use MTOM of the airplane as
an already certificated reference point to compare airplanes. The CO2 Emissions Evaluation
Metric for an airplane is calculated from SAR and a reference geometric factor (RGF) (see
Section 3.3.2) using Specific Air Range. It is expressed in units of kilograms of fuel consumed
per kilometer.
Specific Air Range (SAR) is a measure of fuel efficiency widely used in the airplane industry.
It is a measure of distance traveled per fuel consumed and is calculated using Equation 3-2.
Equation 3-2 - Equation to calculate Specific Air Range of the airplane
TAS
SAR = iir
Where:
TAS is True air speed and Wf is airplane fuel flow
For the purposes of the international Airplane CO2 Emission Standards, the inverse of SAR
would be used to calculate the airplane's metric value. 1/SAR values would be calculated at each
of the three reference airplane mass test points (per Annex 16 Vol. Ill §2.3):
a)	high gross mass: 92 per cent maximum take-off mass (MTOM)
b)	mid gross mass: simple arithmetic average of high gross mass and low gross mass
c)	low gross mass: (0.45 x MTOM) + (0.63 x (MTOM0 924))
At each of these reference points, the airplane is operated at optimum speed and altitude.
The average of the three inverse SAR points will be used to calculate the airplane CO2 metric
value for an individual airplane. The EPA is proposing to use this same procedure to calculate
the fuel efficiency metric value.
3.3.2 Reference Geometric Factor
The Reference Geometric Factor (RGF) is a non-dimensional measure of the fuselage size of
an airplane normalized by 1 square meter. It represents the usable space in the airplane through
the shadow area of the airplane's pressurized passenger compartment. This is defined by Annex
16 Vol. Ill App. 2. Figure3-1 and Figure3-2 show what is included in RGF.
74

-------
Test Procedures
Aeroplane with upper dedt
Aeroplane with single deck
Fuselage outer mould line {OM.)
Macimum vwlh of fuselage OM. for single and upper ded<
Actual fkxx yea
FigureS-l - Crossectional View
Tapered outer skin width,
measured at the frame station
Permanent integrated fuel
tanks within cabin
Forward
boundary
Aft boundary
Forward
boundary with
non-crew seat
Forward
boundary
Figure3-2 - Longitudinal View
3.4 Application of Rules for New Version of an Existing GHG-Certificated Airplane
Under the international CO2 standards, a new version of an existing C02-certificated airplane
is one that incorporates modifications to the type design that increase the MTOM or increase its
CO2 Metric Value more than the No-C02-Change Threshold (described in 3.4.1 below). ICAO's
standards provide that once an airplane is CO2 certificated, all subsequent changes to that
75

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airplane must meet at least the regulatory level of the parent airplane. For example, if the parent
airplane is certificated to the in-production level, then all subsequent versions must also meet the
in-production level. This would also apply to voluntary certifications under ICAO's standards.
If a manufacturer seeks to certificate an in-production airplane type to the level applicable to a
new type design, then future versions of that airplane must also meet the same regulatory level.
Once certificated, subsequent versions of the airplane may not fall back to a less stringent
regulatory GHG level.
If the FAA finds that a new original type certificate is required for any reason, the airplane
would need to comply with the regulatory level applicable to a new type design.
The EPA is proposing provisions for versions of existing GHG-certificated airplanes that are
to the same as the ICAO requirements for the international Airplane CO2 Emission Standards.
These provisions, would reduce the certification burden on manufacturers by clearly defining
when a new metric value must be established for the airplane.
3.4.1 No Fuel Efficiency Change Threshold for GHG-Certificated Airplanes
There are many types of modifications that could be introduced on an airplane design that
could cause slight changes in GHG emissions (e.g., changing the fairing on a light, adding or
changing an external antenna, changing the emergency exit door configuration, etc.). To reduce
burden on both certification authorities and manufacturers, a set of no CO2 emissions change
thresholds were developed for the ICAO Airplane CO2 Emission Standards as to when new
metric values would need to be certificated for changes. The EPA proposes to adopt these same
thresholds in its GHG rules.
Under this proposal, an airplane would be considered a modified version of an existing GHG
certificated airplane, and therefore have to recertify, if it incorporates a change in the type design
that either (a) increases its maximum take-off mass, or (b) increases its GHG emissions
evaluation metric value by more than the no-fuel efficiency change threshold percentages
described below and in Figure 3-3lm:
•	For airplanes with a MTOM greater than or equal to 5,700 kg, the threshold value
decreases linearly from 1.35 to 0.75 percent for an airplane with a MTOM of 60,000 kg.
•	For airplanes with a MTOM greater than or equal to 60,000 kg, the threshold value
decreases linearly from 0.75 to 0.70 percent for airplanes with a MTOM of 600,000 kg.
•	For airplanes with a MTOM greater than or equal to 600,000 kg, the threshold value is
0.70 percent.
1111 Annex 16, Volume III, Part 1, Chapter 1. ICAO, 2017: Annex 16 Volume III - Environmental Protection -
Aeroplane CO2 Emissions, First Edition, 40 pp. Available at:
http://www.Lcao.Lnt/publLcatLons/Pages/catalogue.aspx (last accessed July 15, 2020). The ICAO Annex 16
Volume III Is found on page 16 of English EdLtLon 2020 catalog and Is copyright protected: Order No. AN 16-3.
76

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Test Procedures
1.5%
No-Fuel Efficiency-Change Thresholds

5 1.2%
13
X
o
c
0.9%
(5,700 kg , 1.35%)
i >
	L	J.
No-fuel Efficiency Change
Threshold
	I		
V = -1.10497E-07X + 1.41298E-02
V = -9.25926E-10X + 7.55556E-03
y = 0.007
0.6% (60,000 kg ,0.75%)
(600,000 kg , 0.70%)
C 0.3% f--
0.0%
+
100,000 200,000 300,000 400,000 500,000 600,000
Maximum Take-Off Mass (kg)
700,000
Figure 3-3 - Proposed No Fuel Efficiency Change Thresholds for GHG Certificated Airplanes (ICAO
Adopted No CO2 Emissions Change Thresholds)
The threshold is dependent on airplane size because the potential fuel efficiency changes to an
airplane are not constant across all airplanes. For example, a change to the fairing surrounding a
wing light, or the addition of an antenna to a small business jet may have greater impacts on the
airplane's metric value than a similar change would on a large twin aisle airplane.
These GHG changes would be assessed on a before-change and after-change basis. If there is
a flight test as part of the certification, the metric value (MV) change could be assessed based on
the change in calculated metric value of flights with and without the change.
A modified version of an existing GHG certificated airplane would be subject to the same
regulatory level as the airplane from which it was modified. A manufacturer may also choose to
voluntarily comply with a later or more stringent standard.1"
Under this proposed rule, when a change is made to an airplane type that does not exceed the
no-change threshold, the fuel efficiency metric value would not change. There would be no
method to track these changes to airplane types over time. This feature of the proposed rule
would not remove the requirement for a manufacturer to demonstrate that the airplane type
would still meet the rule after a given change. If an airplane type has, for example, a 10 percent
liv ETM Vol. Ill §2.2.3. ICAO, 2018: Environmental Technical Manual Volume III - Procedures for the CO2
Emissions Certification of Aeroplanes, First Edition, Doc 9501, 64 pp. Available at:
http://www.icao.int/publications/Pages/catalogue.aspx (last accessed July 15, 2020). The ICAO Environmental
Technical Manual Volume III is found on page 77 of the English Edition 2020 catalog and is copyright protected:
Order No. 9501-3.
77

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Test Procedures
compliance margin under the rule, then a small adverse change less than the threshold may not
require the re-evaluation of the airplane metric value. However, if the compliance margin for a
type design is less than the no GHG change criteria, a manufacturer would be required to prove
that it meets the rule to certify the adverse change.
Under the proposed rule, a manufacturer that introduces modifications that reduce GHG
emissions can request voluntary recertification from the FAA. There would be no required
tracking or accounting of GHG emissions reductions made to an airplane unless it is voluntarily
re-certificated.
3.5 Changes for non-GHG Certificated Airplane Types
After January 1, 2023, and until January 1, 2028, an applicant that submits a modification to
the type design of a non-GHG certificated airplane that increases the Metric Value of the
airplanelv, would be required to demonstrate compliance with the in-production rule. This
proposed earlier applicability date for in-production airplanes, of January 1, 2023, is the same as
that adopted by ICAO and is similarly designed to capture modifications to the type design of a
non-GHG certificated airplanes newly manufactured prior to the January 1, 2028, production cut-
off date. The January 1, 2028 production cut-off date was introduced by ICAO as an anti-
backsliding measure that gives notice to manufacturers that non-compliant airplanes will not
receive airworthiness certification after this date.
An application certification of a modified airplane on or after January 1, 2023, would trigger
compliance with the in-production GHG emissions limit provided that the airplane's GHG
emissions metric value for the modified version is above 1.5 percent. As with changes to GHG
certificated airplanes, introduction of a modification that does not adversely affect the airplane
fuel efficiency Metric Value would not be required to comply with this GHG rule at the time of
the change. Manufacturers may seek to certificate any airplane to this standard, even if the
criteria do not require compliance.
As an example, if a manufacturer choses to shorten the fuselage of a type certificated airplane,
such action would not automatically trigger the requirement to certify to the in-production GHG
rule. The fuselage shortening of a certificated type design would not be expected to adversely
affect the metric value, nor would it be expected to increase the certificated MTOM. Again, a
manufacturer may choose to recertificate this change in type design for GHG compliance.
This earlier effective date for in-production airplanes is expected to help encourage some
earlier compliance for new airplanes. However, it is expected that manufacturers would likely
volunteer to certify to the in-production rule when applying to the FAA for these types of
changes.
lv Note that Section 3.5, Changes for non-GHG Certificated Airplane Types, is different than the No GHG Change
Threshold described earlier in section 3.4.1. Section 3.4.1 applies only to airplanes that have previously been
certificated to a GHG rule. Section 3.5 only applies to airplane types that have not been certificated for GHG.
78

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REFERENCES
There are no references for this chapter.
79

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Airplane Performance Model and Analysis
Table of Contents
Chapter 4 Airplane Performance Model and Analysis	81
4.1	Purpose and Scope	81
4.2	Methodology of the EPA Emissions Inventory and Stringency Analysis	81
4.3	Fleet Evolution Model and Data Sources	83
4.3.1	Mapping Base Year Operation to the Growth Forecast Database	83
4.3.2	Retirement Rate	85
4.3.3	Calculating Future Year Growth and Replacement Market Demands	87
4.4	Full Flight Simulation with PIANO and Unit Flight Matrix	89
4.5	Inventory Modeling and Stringency Analysis	90
Table of Figures
Figure 4-1 - Regulatory Analysis Flow Chart	82
Figure 4-2 - The Retirement Curve of Narrow-Body Passenger Airplane Based on Ascend fleet data	86
Table of Tables
Table 4-1 - Two-parameter mapping from 2015 Inventory database to Growth Rate forecast databases	84
Table 4-2 - Retirement Curve coefficients by airplane category	87
Table 4-3 - The G&R airplane available in each market segment	88
Table of Equations
Equation 4-1 - Retirement Curve Equation	85
Equation 4-2 - Number of Operations Equation	88
80

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Airplane Performance Model and Analysis
Chapter 4 Airplane Performance Model and Analysis
4.1	Purpose and Scope
This chapter describes methodologies, assumptions and data sources used to develop the
airplane emissions and fuel burn inventories for the proposed standards and two alternative
stringency scenarios. See chapter 6 for a detailed description of the alternative scenarios. The
results of the emissions inventories and stringency analysis are presented in Chapter 5.
The EPA had participated in the Committee on Aviation Environmental Protection (CAEP) to
analyze the emission impacts of the ICAO Airplane CO2 Emission Standards. CAEP provided a
summary of the results from this analysis in the report of its tenth meeting42, which occurred in
February 2016. However, due to the commercial sensitivity of the data used in the analysis,
much of the underlying information is not available to the public. For the U.S. domestic
standard, however, we are making our analysis, data sources, and model assumptions transparent
to the public so all stakeholders that would be affected by the proposed standards can understand
how the agency derives its decisions. Thus, the EPA has conducted an independent impact
analysis based solely on publicly available information and data sources. An EPA report
detailing the methodology and results of the emissions inventory analysis43 was peer-reviewed
by multiple independent subject matter experts, including experts from academia and other
government agencies, as well as independent technical experts.44
The EPA analysis focuses primarily on modeling the U.S. GHG emissions inventory. Because
aviation is an international industry, and all major airplane and airplane engine manufacturers
sell their products globally, we also model estimated global GHG emissions for reference, but at
a much less detailed level for traffic growth and fleet evolution outside of the U.S.
In developing the inputs for our model, we contracted with ICF11 to conduct an independent
airplane/engine technology and cost assessment for the EPA proposed rulemaking analysis. The
agency uses this ICF technology and cost forecast as the basis for our impact assessment. We
also conducted sensitivity analyses to evaluate the effects of certain model assumptions.
4.2	Methodology of the EPA Emissions Inventory and Stringency Analysis
The methodologies the EPA uses to assess the impacts of the proposed standards and
alternative stringency scenarios can be summarized in a flow chart shown in Figure 4-1.
Essentially, the approach is to develop a baseline emissions inventory which represents the
business as usual case in the absence of standards. This baseline inventory was then compared
with three "stringency" scenarios, representing the proposed standards and two alternative
scenarios.
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Airplane Performance Model and Analysis
EPA Emissions Inventory and Stringency Analysis Flow Chart Diagram
2Q15_lnventory
Base Year
Operations
Growth & Retirement Rates of
each base year operation
T
Fleet Evolution Module
Fleet Evolution & Projected
Future Year Operations
- Baseline (No stringency)
Fleet Evolution & Projected
Future Year Operations
- w/Stringency Responses
. Inventory Module
ll
PIANO Aircraft
Performance
Models &
Databases
Fuel Burn and Emissions
Inventory Calculations
v	
Unit Flight Matrix for Fuel
Burn and Emissions
Flight Simulation Module
J
Figure 4-1 - Regulatory Analysis Flow Chart
The first step of the EPA analysis is to develop an inventory baseline by evolving the base
year operations to future year operations emulating the market driven fleet renewal process
without any stringency requirements. This "no stringency" baseline is developed for the analysis
period of 2015 to 2040. Our approach to developing the baseline is to estimate the growth and
retirement rates of future year operations based on flights with unique route (origin-destination
or 01) pair) and airplane combinations in the base year operations. The growth and retirement
rates for each of the unique base year operations determine the future year market demand which
is then allocated to available airplanes in a Growth and Replacement (G&R) database45' The
growth and retirement rates over the analysis period are obviously a function of macroeconomic
factors like fuel price, materials prices and economic growth. These economic factors are not
considered explicitly in our analysis, but they are embedded in the traffic growth forecast and
retirement rates data as inputs to the EPA analysis. Together with the residual operations from
the base year airplanes, these G&R operations constitute all the operations of in-service fleet for
eveiy future year. The same method is applied to define fleet evolution under various stringency
scenarios. The only difference is under the stringency scenarios, technology responses need to
be taken into consideration. The airplane impacted by a stringency scenario could either be
modified to meet the standards or removed from production without a response. Once the flight
activities for all analysis scenarios are defined by the fleet evolution module, fuel burn and GHG
emissions inventories for the three stringency scenarios are then modeled with a physics-based
airplane performance model known as PIANO46. The differences between the baseline and the
three stringency scenarios are used for assessing the impacts of the stringency scenarios. The
computational processes are grouped into three distinct modules as shown in Figure 4-1. More
detailed accounts of the methods, assumptions, and data sources used for these three
computational modules are given below. The results of the fleet evolution, emissions inventories
and stringency analyses are discussed in the next chapter.
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Airplane Performance Model and Analysis
4.3 Fleet Evolution Model and Data Sources
The EPA fleet evolution model focuses on U.S. aviation, including both domestic and
international flights. U.S. international flights are defined as flights originating from the U.S. but
landing outside the U.S. Flights originating outside the U.S. are not included in the U.S.
inventory. The EPA fleet evolution model is based on FAA' 2015 Inventory Database47
(2015_Inventory) for base year flight activities and FAA's 2015-2040 Terminal Area Forecast48
(TAF) for future year traffic growth. Section 4.3.1 describes how the base year operations are
mapped into the growth forecast database to determine the future year growth rate. Section 4.3.2
describes how the retirement rates of the base year airplanes are determined from the ASCEND
global fleet database. Section 4.3.3 describes how the future market demands are allocated to
available airplanes for growth and replacement.
4.3.1 Mapping Base Year Operation to the Growth Forecast Database
The FAA 2015 Inventory Database is a comprehensive global flight dataset. Its U.S. based
flights have been used as part of the high-fidelity data sources for EPA's official annual GHG
and Sinks report since 199049. Globally, the 2015 inventory database contains 39,708,418 flights
in which 13,508,800 originated from the U.S. Among the U.S. flights, 1,288,657 are by piston
engine airplanes, 341,078 are military operations and 1,393,125 are by small airplanes with
maximum zero fuel weight1" less than 6000 lbs. In our analysis, we exclude military, piston
engine and small light weight airplanes since they are not covered under the proposed
rulemaking. Excluding flights for these three non-covered airplane categories, the database still
contains 10.3 million flights, 1,992.2 billion available seat kilometers (ASK) and 341.6 billion
available tonne kilometers (ATK) in the modeled 2015 U.S. operations.
Likewise, TAF is a comprehensive traffic growth forecast dataset for commercial operations
in both U.S. domestic and U.S. international markets. The 2015-2040 TAF used in this analysis
contains growth forecasts for both passenger and freighter markets based on origin-destination
airport pair and airplane type. In order to determine the growth rate of a base year operation, the
base year operation has to be mapped from the 2015 Inventory Database to a corresponding TAF
market defined by market type (passenger or freighter), origin-destination airport pair, and
airplane type. There is no unique mapping between these two databases. After some iterations
by trial and error and consultation with FAA, we have determined that a two-parameter mapping
using USAGE-CODE and SERVICE_TYPE works the best.
The two-parameter mapping from the FAA 2015 Inventory Database to TAF for growth rate
type identification is shown Table 4-1. USAGE_CODE and SERVICE_TYPE are parameters in
the 2015 Inventory database designed to identify the airplane usage category and the service type
of a given flight. Possible USAGE_CODEs are P for passenger, B for business, C for cargo, A
for attack/combat, and O for other. Possible SERVICE_TYPEs are C for commercial, G for
general aviation, F for freighter, M for military, O for other, and T for air taxi. For this analysis,
we filter out SERVICE_TYPEs of M (military), O (other), and T (air taxi) and only keep C
lvl The maximum zero fuel weight is the maximum permissible weight of an airplane with no disposable fuel or oil.
It is used as a prescreening filter to exclude individual airplane from further analysis in the absence of precise
maximum takeoff weight information. Maximum takeoff weight thresholds of 5,700 kg for jet airplanes and 8,618
kg for turboprop airplanes are applied by airplane type to limit the analysis to the subset of airplanes covered by
the proposed GHG standards.
83

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Airplane Performance Model and Analysis
(commercial), G (general aviation), and F (freighter). Likewise, for USAGE_CODE, we filter
out A (attack/combat) and 0 (other) but keep P (passenger), B (business) and C (cargo) for this
analysis.
Combinations of the remaining USAGE_CODE and SERVICE_TYPE subdivide the total
market into nine sub-market categories as shown in Table 4-1. The size of each sub-market
category based on the two-parameter mapping is summarized in Table 4-1 to give a sense of their
relative contributions to the overall fleet operations by available seat kilometer (TOTAL_ASK),
available tonne kilometer (TOTAL_ATK), and number of operations (2015_OPS). In
consultation with FAA, these nine sub-markets are mapped into three growth rate types (under
the GR_Map column in Table 4-1) for the purpose of determining their growth rate forecast for
future year operations. Again, in GR_Map, G is for general aviation, F is for freighter and P is
for passenger. For U.S. passenger (P) and freighter (F) operations, TAF is used to determine the
growth rates for U.S. origin-destination (OD) pairs and airplane types from 2015 to 2040.
Table 4-1 - Two-parameter mapping from 2015 Inventory database to Growth Rate forecast databases
USAGE_CODE
SERVICE_TYPE
GR_Map
TOTAL_OPS
TOTAL_ASK
TOTAL_ATK
B - Business
C- Commercial
G - General
5.8148E+05
4.5898E+09
9.8501E+08
B
F - Freight
F - Freight
6.4350E+03
1.4580E+06
1.1399E+07
B
G - General
G
1.3937E+06
1.3166E+10
2.8144E+09
C - Cargo
C
F
2.2645E+05
2.8492E+10
3.7362E+10
C
F
F
4.7665E+05
5.2309E+09
6.6587E+10
C
G
G
9.6400E+03
6.1929E+08
1.8029 E+09
P - Passenger
C
P - Passenger
2.7432E+07
7.0697E+12
1.0836E+12
P
F
F
3.1517E+05
8.8414E+10
2.6023E+10
P
G
G
4.1658E+06
1.2560E+12
2.0427E+11
In mapping the base year operations to TAF to determine their corresponding growth rate, if
there are exact OD-pair and airplane matches between the two databases, the exact TAF year-on-
year growth rates are applied to grow 2015 base year operations to future years. For cases
without exact matches, the growth rates of progressively higher-level aggregates will be used to
grow the future year operations.48 For example, if there is no match in exact origin-destination
airport pair, the airport pair will be mapped to a route group (either domestic or international),
and the growth rate of the route group will be used instead to grow the operation. If there is no
match in airplane type (e.g., B737-8 MAX, B777-9X, etc.), the airplane category (e.g., narrow
body passenger, wide body freighter, etc.) as defined in the TAF will be used to map the growth
rate.
Since general aviation is not covered in TAF, we use the forecasted growth rate of 1.6% for
all turboprop operations based on the FAA Aerospace Forecast (Fiscal Year 2017-2037)50. For
U.S. business jet operations, we use the 3% compound annual growth rate published in the same
FAA Aerospace Forecast (Fiscal Year 2017-2037).50
For non-U.S. flights, we use an average compound annual growth rate of 4.5% for all
passenger operations and 4.2% for all freighter operations based on ICAO long-term traffic
forecast for passenger and freighters.51 For non-U.S. business jet operations, we use the global
84

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Airplane Performance Model and Analysis
average growth rate of 5.4% based on Bombardier's Business Aircraft Market Forecast 2016-
2025.52
Given the classification of the two-parameter mapping table, we have determined that the
eighth row of the mapping table (where the USAGE_CODE = "P" and SERVICE_TYPE = "F")
is converted freighters which are freighters converted from used passenger airplanes after the end
of their passenger services. These converted freighters are not subject to the proposed GHG
standards, so they are excluded from all inventory data reported in this Draft TSD.
4.3.2 Retirement Rate
The retirement rate of a specific airplane is determined by the age of the airplane and the
retirement curve associated with the airplane category. The retirement curve is the cumulative
fraction of retirement expected as the airplane ages. It goes from 0 to 1 as the airplane age
increases. The retirement curves can be expressed as a Sigmoid or Logistic function in the form
of
Equation 4-1 - Retirement Curve Equation
RC(x) = 1/(1 + ea~bx)
where RC is the retirement curve function, a and b are coefficients that change with airplane
category andx is the age of the airplane.
The reason to choose this type of retirement function is because it is a well-behaved function
that matches well with historical retirement data of known airplane fleet. Figure 4-2 illustrates
the characteristic "S" shape of a historical survival curve, SC(x), where SC(x) = 1 - RC(x). Note
that the ratio of the two coefficients in Equation 4-1, i.e., a/b, represents the half-life of the
airplane fleet where 50% of the fleet survives and 50% retires. The slope of the retirement curve
(or percent retired per year) at half-life is b/4. So, the larger the coefficient b is, the higher the
rate of retirement will be at half-life. The retirement curve is also an antisymmetric function
with respect to x = a/b and has long tails at both ends of the age distribution (very young and
very old airplanes in the fleet).
85

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Airplane Performance Model and Analysis
Narrow Body Passenger Retirement Curve
100%
80%
"S 60%
>
3
LO
SO
0s-
40%
20%
0%
0
10	20	30
Airplane Age
40
1970
• 1971
1972
• 1973
1974
• 1975
1976
• 1977
1978
• 1979
1980
• 1981
1982
• 1983
1984
1985
1986
10QQ
• 1987
M 1QQQ
iyoo
1990
•	iyoy
•	1991
1992
• 1993
1994
• 1995
1996
1997
1998
• 1999
2000
• 2001
2302
• 2003
2304
• 2005
2306
• 2007
2308
2009
2310
• 2011
2312
• 2013
2314
• 2015
CAEP10NB
	BFSC
Figure 4-2 - The Retirement Curve of Narrow-Body Passenger Airplane Based on Ascend53 fleet data
Retirement curves of major airplane categories used in this EPA analysis are derived
statistically based on data from the FlightGlobal's Fleets Analyzer database53 (also known as
ASCEND Online Fleets Database — hereinafter "ASCEND"). Table 4-2 lists the numerical
values of these coefficients in the retirement curves for major airplane categories. The retirement
curves so established are consistent with published literature from Boeing and Avolon in terms
of the economic useful life of airplane categories. However, it is recognized from other sectors
(e.g., light duty vehicles) that the retirement curves are not necessarily exogenously fixed but
rather a function of the relative price of new versus used vehicles; fuel prices; repair costs; etc.
Furthermore, when regulations are vintage differentiated (i.e., when new vehicles are subject to
stricter requirements than older vintages), it has been shown that the economically useful life of
the existing fleet can be extended. The higher cost and sometimes diminished performance of
compliant new vehicles makes it economically worthwhile to extend the life of older vehicles
that would otherwise have been retired. These extraneous factors, however, are not considered
in this analysis.
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Airplane Performance Model and Analysis
Table 4-2 - Retirement Curve coefficients by airplane category
LQ
LQF
Ri
SA
SAF
TA
TAF
TP
AirplaneCategory
BJ
Description
Business Jet
Large Quad
a
6.265852341	0.150800149
5.611526057	0.223511259
6.905900732	0.205267334
4.752779141	0.178659236
5.393337195	0.222210782
6.905900732	0.205267334
5.611526057	0.223511259
6.905900732	0.205267334
3.477281304	0.103331799
b
large Quad Freighter
Regional Jet
Single Aisle
Single Aisle Freighter
Twin Aisle
Twin Aisle Freighter
Turboprop
For each operation in the base year database (2015 Inventory), if the airplane tail number is
known, the retirement rate is based on exact age of the airplane from the ASCEND global fleet
database. If the airplane's tail number is not known, the aggregated retirement rate of the next
level matching group (e.g., airplane category or airplane type' as defined by ASCEND) will be
used to calculate the retirement rates for future years.
4.3.3 Calculating Future Year Growth and Replacement Market Demands
Combining the growth and retirement rates together, we can determine the total future year
market demands for each base year flight. These market demands are then allocated by equal
product market sharelvu to available G&R airplanes competing in the same market segment as the
base year flight. The available G&R airplanes for various market segments are based on the
technology responses developed by ICF, as described in Chapter 2 of the Draft TSD.54 The
G&R airplanes in each market segment are listed in Table 4-3. ICF technology responses also
include detailed information about the entiy-into service year and the end-of-production year for
each current and future in-production airplane out to 2040.
lvn EPA uses equal product market share (for all airplanes present in the G&R database), but attention has been paid
to make sure that competing manufacturers have reasonable representative products in the G&R database.
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Airplane Performance Model and Analysis
Table 4-3 - The G&R airplane available in each market segment
Market
Segment
Description
G&R Airplane
CBJ
Corporate Jet
A318-112/CJ, A319-133/CJ, B737-700IGW (BBJ), B737-8 (BBJ)
FR
Freighter
A330-2F, B747-8F, B767-3ERF, B777-2LRF, TU204-F, AN74-F/PAX, B777-
9xF, A330-800-NEOF
LBJ
Large Business Jet
G-5000, G-6000, GVI, GULF5, Global 7000, Global 8000
MBJ
Medium Business Jet
CL-605, CL-850, FAL900LX, FAL7X, ERJLEG, GULF4
RJ 1
Small Regional Jet
CRJ700, ERJ135-LR, ERJ145, MRJ-70
RJ 2
Medium Regional Jet
CRJ900, ERJ175, AN-148-100E, AN-158, EJ-175 E2
RJ_3
Large Regional Jet
CRJ1000, ERJ190, ERJ195, RRJ-95, RRJ-95LR, TU334, MRJ-90, ERJ-190 E2,
ERJ-195 E2
SA_1
Small Single Aisle
A318-122, A319-133, B737-700, B737-700W, A319-NEO, B737-7MAX,
CS100, CS300, MS-21-200
SA_2
Medium Single Aisle
A320-233, B737-800, B737-800W, A320-NEO, B737-8MAX, MS-21-300,
C919ER
SA_3
Large Single Aisle
A321-211, B737-900ER, B737-900ERW, TU204-300, TU204SM, TU214,
A321-NEO, B737-9MAX
SBJ 1
Small Business Jet 1
CNA515B, CNA515C, EMB505, PC-24
SBJ_2
Small Business Jet_2
Learjet 40XR, Learjet 45XR, Learjet 60XR, CNA560-XLS, Learjet 70, Learjet
75
SBJ 3
Small Business Jet 3
CNA680, GULF150, CNA680-S
SBJ 4
Small Business Jet 4
CL-300, CNA750, FAL2000LX, G280, CNA750-X
TA 1
Small Twin Aisle
A330-203, A330-303, B767-3ER, B787-8, A330-800NEO, A330-900-NEO
TA 2
Medium Twin Aisle
A350-800, A350-900, B787-9, B787-10
TA 3
Large Twin Aisle
B777-200ER, A350-1000, B777-8x
TA_4
Very Large Twin
Aisle
A380-842, B747-8, B777-200LR, B777-300ER, B777-9x
TP 1
Small Turboprop
ATR42-5, 1 LI 14-100, AN-32P, AN140
TP 2
Medium Turboprop
ATR72-2
TP 3
Large Turboprop
Q400
We allocate the market demanc
based on available seat kilometer (ASK) for passenger
operations, available tonne kilometer (ATK) for freighter operations and number of operations
for business jets. Of course, given the number of seats for passenger airplane, payload capacity
for freighters and the great circle distance for each flight, all these can be converted to a common
activity measure, i.e., number of operations. The formula for calculating number of operations
for out years is given in Equation 4-2.
Equation 4-2 - Number of Operations Equation
GR(y) + RET(y)
NOP(y) =	 ]y|(c	NOP( 2015)
where NOP(y) is number of operations in year y,
GR(y) is the growth rate in year y
RET(y) is the retirement rate in yeary
N(c,y) is the number of available airplanes in market segment c and year y
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Airplane Performance Model and Analysis
As described in Chapter 2 of this Draft TSD (see Table 2-1), ICF technology responses
include continuous improvement in metric value (or fuel efficiency improvement) for all G&R
airplanes from 20 1 055 to 2040. ICF technology responses also include estimated MV
improvements for long-term replacement airplanes (see Table 2-4) beyond the end of production
of current in-production and project airplanes. This is meant to establish a baseline where
current in-production airplanes are continuously improving and new type design airplanes are
introduced periodically to replace airplane models that are going out of production due to market
competition. In order to capture these dynamically changing airplane efficiency improvements,
our fleet evolution model tracks the market share of every new-in-service airplane entering the
fleet each year and applies the annual fuel efficiency improvement via an adjustment factor
according to the vintage year of the airplane in the fleet. For stringency analysis, if an airplane
fails a stringency limit and needs to improve its MV to comply with the standard, we apply the
adjustment factor in the same manner to establish the emissions under the influence of the
stringency limit.
4.4 Full Flight Simulation with PIANO and Unit Flight Matrix
The purpose of the full flight simulation module is to calculate instantaneous and cumulative
fuel burn, flight distance, flight altitude, flight time, and emissions by modeling airplane
performance for standardized flight trajectories and operational modes. PIAN0lvm version 5.4
was used for all the emissions modeling. PIANO is a physics-based airplane performance model
used widely by industry, research institutes, non-governmental organizations and government
agencies to assess airplane performance metrics such as fuel efficiency and emissions
characteristics based on airplane types and engine types. PIANO v5.4 (2017 build) has 591
airplane models (including many project airplanes still under development, e.g., the B777-9X)
and 56 engine types in its airplane and engine databases. We use these comprehensive airplane
and engine data to model airplane performance for all phases of flight from gate to gate including
taxi-out, take-off, climb, cruise, descent, approach, landing, and taxi-in in this analysis.
To simplify the computation, we made the following modeling assumptions: 1) Assume
airplanes fly the great circle distance (which is the shortest distance along surface of the earth
between two airports) for each origin-destination (OD) pair. 2) Assume still air flights and ignore
weather or jet stream effects. 3) Assume no delays in takeoff, landing, en-route, and other flight
related operations. 4) Assume a load factor of 75% maximum payload capacity for all flights
except for business jet where 50% is assumed. 5) Use the PIANO default reserve fuel rulellx for a
given airplane type. 6) Assume a one-to-one relationship between metric value improvement and
fuel burn improvement for airplanes with better fuel efficiency technology insertions (or
technology responses).
When jet fuel is consumed in an engine, the vast majority of the carbon in the fuel reacts with
oxygen to form CO2. To convert fuel consumption to CO2 emissions, we used the conversion
lvm PIANO is the Aircraft Design and Analysis Software by Dr. Dimitri Simos, Lissys Limited, UK, 1990-present;
Available at www.piano.aefo (last accessed March 16, 2020). PIANO is a commercially available airplane
design and performance software suite used across the industry and academia.
hx por typicai medium/long-haul airplanes, the default reserve settings are 200 nm diversion, 30 minutes hold, plus
5% contingency on mission fuel. Depending on airplane types, other reserve rules such as U.S. short-haul,
European short-haul, NBAA-IFR or Douglas rules are used as well.
89

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Airplane Performance Model and Analysis
factor of 3.16 kg/kg fuel for CO2 emissions, and to convert to the six well-mixed GHG
emissions, we used a slightly higher conversion factor of 3.19 kg/kg fuel for CO2 equivalent
emissions. It is important to note that in regard to the six well-mixed GHGs (CO2, methane,
nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride), only two of these
gases — CO2 and nitrous oxide (N2O) — are reported (or emitted) for airplanes and airplane
engines.49 The method for calculating CO2 equivalent emissions is based on SAE AIR 5715,
entitled Procedures for the Calculation of Airplane Emissions56 for N2O emissions, and the EPA
publication Emissions Factors for Greenhouse Gas Inventories57 for the 100-year global
warming potential.
Given the flight activities defined by the fleet evolution module in the previous section, we
generate a unit flight matrix to summarize all the PIANO outputs of fuel burn, flight distance,
flight time, emissions, etc. for all flights uniquely defined by a combination of departure and
arrival airports, airplane types, and engine types. This matrix includes millions of flights and
forms the basis for all the regulatory scenarios and sensitivity studies. To reduce the
computational workload of such a huge task in stringency analysis, we pre-calculate these full
flight simulation results and store them in a database of 50 distances and 50 payloads for each
airplane and engine combination. The millions of flights in the unit flight matrix are interpolated
from the 50x50 flight distance/payload database.
4.5 Inventory Modeling and Stringency Analysis
The GHG emissions calculation involves summing the outputs from the first two modules for
every flight in the database. This is done globally, and the U.S. portion is segregated from the
global dataset. The same calculation is done for the baseline and the proposed GHG standards
and two alternative scenarios. When a surrogate airplane is used to model any airplane that is
not in the PIANO database or when a technology response is required for any airplane to pass a
stringency limit, an adjustment factor is also applied to model the expected performance of the
intended airplane and technology responses.
The differences between the proposed GHG standards and alternative scenarios and that of the
baseline provide the quantitative measures for the agency to assess the emissions impacts of the
proposed GHG standards.
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Airplane Performance Model and Analysis
REFERENCES
42ICAO, 2016: Tenth Meeting Committee on Aviation Environmental Protection Report, 112 February 2016,
Committee on Aviation Environmental Protection, Document 10069, 432pp, is found on page 27 of the English
Edition ICAO Products & Services 2020 Catalog and is copyright protected; Order No. 10069. For purchase
available at: https://www.icao.int/publications/catalogue/cat_2020_en.pdf (last accessed March 17, 2020). The
summary of technological feasibility and cost information is located in Appendix C (starting on page 5C-1) of this
report.
43	U.S. EPA, 2020: Technical Report on Aircraft Emissions Inventory and Stringency Analysis, July 2020.
44	RTI International and EnDyna, EPA Technical Report on Aircraft Emissions Inventory and Stringency Analysis:
Peer Review, July 2019, 157pp.
45	The Growth and Replacement database contains all the available in production and in development airplanes
known to the agency for renewing the global in-service fleet in the analysis period of 2015-2040. This G&R
database together with technology responses developed by ICF is available in the 2018 ICF Report.
46	PIANO is the Aircraft Design and Analysis Software by Dr. Dimitri Simos, Lissys Limited, UK, 1990-present;
Available at www.piano.aero (last accessed March 18, 2020). PIANO is a commercially available aircraft design
and performance software suite used across the industry and academia.
47	FAA, Inventory Database is developed by the U.S. Federal Aviation Administration (FAA). Commercial airplane
jet fuel burn and carbon dioxide (CO2) emissions estimates were included in the U.S. Inventory using radar-
informed data from the FAA Enhanced Traffic Management System (ETMS) for 2000 through 2016 as modeled
with the Aviation Environmental Design Tool (AEDT). For this analysis, EPA only uses the operations data from
the 2015 Inventory Database to develop the fleet evolution and emissions modeling as described in this document.
48	FAA, 2015-2040 Terminal Area Forecast, the Terminal Area Forecast (TAF) is the official FAA forecast of
aviation activity for U.S. airports. It contains active airports in the National Plan of Integrated Airport Systems
(NPIAS) including FAA-towered airports, Federal contract-towered airports, nonfederal towered airports, and non-
towered airports. Forecasts are prepared for major users of the National Airspace System including air carrier, air
taxi/commuter, general aviation, and military. The forecasts are prepared to meet the budget and planning needs of
the FAA and provide information for use by state and local authorities, the aviation industry, and the public.
49	EPA, 2019: Inventory of US Greenhouse Gas Emissions and Sinks, EPA develops an annual report that tracks
U.S. greenhouse gas emissions and sinks by source, economic sector, and greenhouse gas going back to 1990. EPA
publishes the draft report in February to allow public comment prior to publishing the final report by April 15 of
every year. The document is available online at the following EPA website^
https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks (last accessed March 17,
2020)
50	FAA, 2018, FAA Aerospace Forecast, Fiscal Years 2017-2037, Table 29 Active General Aviation and Air taxi
Hours Flown, Average Annual Growth 2017-2037. The document is available online at the FAA website.
https://www.faa.gov/data research/aviation/aerospace forecasl:s/media/FY2017-37 FAA Aerospace Forecast.pdf
jlast accessed March 17, 2020)
51	ICAO, 2016, long Term Traffic Forecasts, Passenger and Cargo, July 2016. The document is available online at
the ICAO website. https://www.icao.int/Meetings/aviationdataseminar/Documents/ICAO-Long-Term-Traffic-
Forecasts- Iuly-2016.pdf (last accessed March 17. 2020)
52	Bombardier, 2015, 2016-2025 Bombardier's Business Aircraft Market Forecast. The report is available online at
the Bombardier website, https://businessaircraft.bombardier.com/sites/default/files/2018-03/market forecast en.pdf
(last accessed March 17, 2020)
53	FlightGlobal Fleets Analyzer is a subscription based online data platform providing comprehensive and
authoritative source of global aircraft fleet data (also known as ASCEND database) for manufacturers, suppliers and
MRO providers, https://signin.cirium.com/ (last accessed March 17, 2020)
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Airplane Performance Model and Analysis
54ICF, 2018: Aircraft COi Cost and Technology Refresh and Industry Characterization, Final Report, EPA Contract
Number EP-C-16-020, September 30, 2018.
55	For this analysis with 2015 as the base year, we only use the continuous improvement data from 2015 to 2040.
56	SAE, 2009: Procedures for the Calculation of Aircraft Emissions', AIR 5715, 2009-07. This document can be
purchased at SAE website, and is copyright protected, https://www.sae.org/standards/content/air5715/.
57	EPA, 2014, Emissions Factors for Greenhouse Gas Inventories, EPA, last modified 4, April 2014.
https://www.epa.gov/sites/production/files/2015-07/docunients/emission-factors 2014.pdf
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Impacts on Emissions and Fuel Consumption
Table of Contents
Chapter 5 Impacts on Emissions and Fuel Burn	95
5.1	Executive Summary	95
5.2	Introduction	95
5.3	Fleet Evolution Results and Baseline Emissions	96
5.3.1	Fleet Evolution Results	97
5.3.1.1 Conclusions of the Fleet Evolution Results	103
5.3.2	Baseline Emissions	104
5.3.2.1 Discussions on baseline modeling	105
5.4	Stringency Analysis of U.S. and Global CO2 Emission Impacts	106
5.5	Sensitivity Case Studies	108
5.5.1	Scenario 3 Sensitivity to Continuous Improvement	108
5.5.2	Scenario 3 Sensitivity to Extending Production of A380 and B767-3ERF to 2030112
5.5.3	Scenario 3 Sensitivity to Combined Effects of Continuous Improvement and
Extended Production	114
5.5.4	Similar Sensitivity Studies for Scenarios 1 and 2	116
Table of Figures
Figure 5-1 - Global total growth and replacement operations in years 2015-2040	97
Figure 5-2 - Comparison of U.S. Passenger fleet Available Seat Kilometer of ICAO, EPA and TAF	99
Figure 5-3 - Comparison of U.S. Turboprop fleet Available Seat Kilometer of ICAO, EPA and TAF	99
Figure 5-4 - Comparison of U.S. Regional Jet fleet Available Seat Kilometer of ICAO, EPA and TAF	100
Figure 5-5 - Comparison of U.S. Freighter fleet number of operations for ICAO, EPA and TAF	101
Figure 5-6 - Comparison of U.S. Freighter fleet Available Tonne Kilometer of ICAO, EPA and TAF	102
Figure 5-7 - Total Available Tonne Kilometer of subsets of flights in EPA and TAF with and without match origin-
destination pair (OD), aircraft type (AC) and airplane category (CAT)	102
Figure 5-8 - Comparison of U.S. Business Jet fleet number of operations for ICAO, EPA and TAF	103
Figure 5-9 - Range of CO2 emissions baselines with various fleet evolution and continuous improvement
assumptions	105
Figure 5 10 CO2 emissions of A380-8 and market segment TA_4 for the baseline and Scenario 3	107
Figure 5 11 Cumulative reduction of CO2 emissions from 2023 to 2040 for Scenario 3	108
Figure 5-12 - CO2 Emissions of Baseline and Scenario 3 for ICAO and EPA (w & w/o continuous improvement)
Cases	110
Figure 5-13 - Zoom-in Picture of CO2 Emissions of Impacted Airplane A380-8 and Market Segment TA_4 for EPA
Scenario 3 with and without Continuous Improvement	110
Figure 5-14 - Cumulative CO2 Reduction of Scenario 3 for ICAO and EPA (w & w/o continuous improvement)
cases	Ill
Figure 5-15 - Cumulative U.S. CO2 Reduction for EPA Scenario 3 with & without Continuous Improvement	Ill
Figure 5-16 - CO2 emissions of A380-8 with two different end of production (EOP) assumptions (2025 versus 2030)
for EPA baseline and Scenario 3	112
Figure 5-17 - CO2 emissions of B767-3ERF with two different end of production assumptions (2023 versus 2030)
for EPA baseline and Scenario 3	113
Figure 5-18 - EPA main analysis versus sensitivity study: in cumulative reduction of CO2 emissions from 2023 to
2040 for Scenario 3	113
Figure 5-19 - Zoom-in view of CO2 Emissions of A380-8 and Market Segment TA_4, for Extended Production to
2030, with and without Continuous Improvement	114
Figure 5-20 - Zoom-in view of CO2 Emissions of B767-3ERF and Market Segment FR, for Extended Production to
2030, with and without Continuous Improvement	115
Figure 5-21 - Cumulative CO2 Reduction of Scenario 3 for ICAO and EPA (Sensitivity Study of Extended
Production to 2030 for A380 and B767F, with & without continuous improvement)	115
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Impacts on Emissions and Fuel Consumption
Figure 5-22 - Cumulative U.S. CO2 Reduction of Scenario 3 for the Sensitivity Study of Extended Production to
2030 for A380 and B767F, with & without continuous improvement	116
Figure 5-23 - Summary of Sensitivity to Model Assumptions for Scenarios 1, 2 and 3	117
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Impacts on Emissions and Fuel Consumption
Chapter 5 Impacts on Emissions and Fuel Burn
5.1	Executive Summary
EPA analyzed the costs and emissions reductions for the proposed standards and two
alternative scenarios. The first alternative scenario (Scenario 2) was for a 5-year pull-ahead (or
5-year earlier effective date) of the proposed in-production standard. The second alternative
scenario (Scenario 3) was for a pull-ahead combined with a more stringent level comparable to
the new type standard. These alternative scenarios are described in more detail later in section
6.1.2 (of Chapter 6).
The main conclusion of the impact analysis for the proposed airplane GHG emissions rule is
that it would result in no costs (other than reporting costs) and no emission reductions. This is
because the ICAO standards are technology-following standards and all manufacturers have
products that either already meet the standards or have new products under development that will
meet the standards by their effective dates. The major effect of the proposed standards is to align
with ICAO standards in order to provide a level playing field for U.S. manufacturers and to
prevent future airplanes from backsliding or incorporating technologies that would have an
adverse effect on GHG emissions.
Of the two alternative stringency scenarios the agency has analyzed, the pull-ahead scenario
of the in-production standard also offers no additional benefit but has a much tighter timeline for
manufacturers to certify their engines due to the 5-year pull-ahead from the ICAO production
cut-off date. The other more stringent scenario (Scenario 3) would only result in modest
emission reductions (1.4 Mt of cumulative U.S. CO2 reductions over the period of 2023-2040).lx
This result is because the only airplane that is impacted by Scenario 3 is the A380. None of the
U.S. airlines have the A380 in their fleets, and thus, under Scenario 3 the emissions reduction
impacts from both U.S. domestic and international flights are limited.
5.2	Introduction
Market forces historically have driven fuel efficiency improvements because fuel efficiency is
a major part of the direct operating cost of air carriers, and it influences their airplane purchasing
decisions. EPA's Guidelines for Economic Analysis, OMB's A-4, and standard cost-benefit
analysis all call for a ceteris paribus1® baseline scenario, against which a policy scenario is
compared. From this perspective, a business as usual (BAU) baseline which includes market-
driven improvements in the absence of the proposed GHG standards would be the best measure
for assessing impact of the proposed standards. In fact, EPA regulatory impact analyses in other
sectors all use such BAU baselines to assess the impacts of emission regulations on the regulated
sectors.
It is thus important to determine the BAU baseline as accurately as possible by
knowledgeable and independent third-party experts. EPA contracted with ICF to conduct such
an independent study to develop the best estimates of the BAU improvements for airplanes and
engines in detail by airplane models and engine types for the near- and mid- term (2010-2030)
lx As described later in section 6.4 (of Chapter 6), estimated net benefits (benefits minus costs) range from -$285
million to -$261 million, at 7 and 3 percent discount rates respectively
1x1 Ceteris paribus means with other conditions remaining the same (all other things being equal).
95

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Impacts on Emissions and Fuel Consumption
and long-term (2030-2040) timeframes, based on technology feasibility and economic viability
for each of airplane/engine types. The main analysis results presented in this chapter are based
on the fleet evolution and technology responses derived from this ICF study58.
Inherent in any modeling of future emissions is the uncertainty associated with predictions of
the future. The agency has conducted a number of sensitivity studies in an attempt to quantify
the effects of certain fleet evolution and technology response parameters, specifically the end-of-
production timing and continuous-improvement (which are improvements expected from BAU
developments) assumptions. These sensitivity studies provide an estimate of the uncertainties
when we vary such parameters one at a time or in combinations.
5.3 Fleet Evolution Results and Baseline Emissions
As described in Chapter 4 of the Draft TSD, the EPA fleet evolution model aims to develop
future operations of the overall airplane fleet based on the base year operations assuming a fixed
network structure (no new routes or time-varying network configurations). We use a very simple
market allocation method in which each competing airplane within a market segment is given an
equal market share. The market allocation is based on airplane types and their operations
measured in available seat kilometer (ASK) or available tonne kilometer (ATK) or number of
operations since they directly determine the emissions output. We are not tracking flights and
airplane deliveries at individual airplane operator or airline level.
In developing future year operations, all growth and replacement (G&R) operations and
residual legacy operations in future years are expressed in fractions of the base year operations in
our analysis. The growth and replacement operations come from new airplanes entering into
service to fill the market demands from increased air traffic and retirement of in-service fleet in
future years. The residual legacy operations are the remaining base year operations expected in
future years after retirement of a portion of the base year fleet.
The market allocation method for G&R operations is applied to each individual flight in the
base year. Together with the residual operations from the base year, the total fleet operations in
any given year are made up of three parts, i.e., growth, retirement and residual operations. This is
true at any aggregate levels from individual flight to total global fleet. To illustrate the
relationship between base year operations, growth, retirement and residual operations in future
years, the overall global fleet growth and replacement operations are depicted as an example in
Figure 5-1 where the lower line defines the residual (or remaining) operations while the upper
line defines the growth projection. The area between the base year operations (the dashed
horizontal line) and the growth line is the growth operations. The area between the base year
operations and the residual line is the retirement operations. The area below the residual line is
the residual operations from the legacy fleet of the base year. The combined growth and
retirement operations in each year will be the total annual market demands that need to be filled
by G&R airplanes. The G&R fleet in any future year though is comprised of G&R airplanes
entering in service from all previous years. The new enter-into-service airplanes themselves will
retire according to their respective retirement curves. Thus, the market share and distribution of
operations among the in-service fleet change from year to year, and our fleet evolution model
tracks these changes for each G&R airplane type and each enter-into-service year. Thus, we are
able to assign proper BAU improvements according to the year a G&R airplane enters into
96

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Impacts on Emissions and Fuel Consumption
service. Fleet evolution results and baseline emissions all depend on the exact age distribution of
the G&R fleet.
Global: Total
Number of Operations
	 Growth
	 Residual
Growth
Operations
Q.
Base Year Operations
X!
Replacement
Operations
Residual Operations
0.0
2015
2020
2025
2030
2035
2040
Year
Figure 5-1 - Global total growth and replacement operations in years 2015-2040
5.3.1 Fleet Evolution Results
Fleet evolution defines how the future fleet is composed and how future fleet operations are
distributed based on the operations of a base year and the market growth forecast from the base
year. It is the basis for calculating future year emissions and evaluating the impact of stringency
scenarios. The fleet evolution of the EPA analysis is developed independently of the ICAO
analysis. Per discussions in section 4.3, it is based on FAA's 2015 inventory database for the
base year operations and FAA's 2015-2040 TAFK" for future traffic growth. Since it is
developed independently, it is not directly comparable to the ICAO dataset. Nevertheless, we
will compare our fleet evolution results with ICAO and TAF data for a consistency check. There
is no right or wrong in this comparison, but any outstanding differences may warrant some
lxu pAA; 2015-2040 Terminal Area Forecast, the Terminal Area Forecast (TAF) is the official FAA forecast of
aviation activity for U.S. airports. It contains active airports in the National Plan of Integrated Airport Systems
(NPIAS) including I AA lowered airports, Federal contract-towered airports, nonfederal towered airports, and
non-towered airports. Forecasts are prepared for major users of the National Airspace System including air
carrier, air taxi/commuter, general aviation, and military. The forecasts are prepared to meet the budget and
planning needs of the FAA and provide information for use by state and local authorities, the aviation industry,
and the public.
97

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Impacts on Emissions and Fuel Consumption
discussion to ensure that they will not skew the results and affect the policy decisions in an
unexplainable manner.
Figure 5-2 compares the EPA fleet evolution results with the ICAO results. The EPA analysis
results are close to the ICAO results but differ by up to 10% in the analysis period of 2015-2040.
This is expected because there are many fundamental differences between the two analyses.
First, the EPA fleet evolution for this proposed rule is based on FAA 2015 Inventory Database,
while ICAO's fleet evolution is based on 2010 Common Operations Database (COD)lxm.
Second, the EPA growth forecast is based on FAA 2015-2040 Terminal Area Forecast (TAF),
while the ICAO growth forecast is based on CAEP-FESGlxiv consensus traffic forecast and
industry-provided fleet forecast for passenger, freight and business jets for 2010-2040. So the
two fleet evolution models are based on different data sources in both the base year operation
and the growth rate forecast. Coming within 10% differences in a 25-year span is actually quite
noteworthy considering the EPA fleet evolution for the U.S. operations is very detailed based on
the FAA data while the ICAO model treats all U.S. domestic operation as growing at one
uniform growth rate.
We also compare the EPA fleet evolution results with FAA TAF mainly to confirm that the
growth rates are consistent between the two since EPA analysis growth rates are sourced from
TAF. But because the two databases (2015 Inventory and TAF) are developed and maintained
by different groups for different purposes using different data sources, some differences exist in
the base year operations, most notably, in the international freight operations. Many operations
exist in one database but not in the other and vice versa. Our fleet evolution strategy is to evolve
future year fleet operations solely based on FAA 2015 Inventory for the base year operations.
So, in cases where the base year operations in TAF are different from those in the 2015
Inventory, the TAF operational data are ignored. TAF is only used to determine the growth rate
of the fleet. The challenge for this strategy is in mapping the base year operations correctly onto
TAF to find the proper growth rates forecast for the operations in future years. With this
strategy, we will always get a unique solution for future year operations with a given mapping of
base year operations from 2015 Inventory to TAF, but there is no guarantee that the total
operations so derived in any year will be the same as the TAF. By using a two-parameter
mapping, we were able to refine the grouping of base year operations and improve the mapping
between the two databases. Although some large differences still exist between the two, further
reconciliation is beyond the scope of this project. By using the two-parameter mapping, we can
also isolate the converted freighter operations and exclude them from stringency analysis
because they are not subjected to the proposed GHG standards. This exclusion also makes the
EPA analysis freighter results more comparable to ICAO's, but other differences remain as
explained later.
1x111 Common Operations Database (COD) is a comprehensive global flight database developed and maintained by
the Modeling and Database Group (MDG), which is a technical group under ICAO's Committee on Aviation
Environmental Protection (CAEP). COD is used for trends analysis of aviation environmental impacts and
stringency analysis for ICAO standards.
lxlv CAEP-FESG refers to the Forecasting and Economic Analysis Support Group which is the technical group
tasked to develop fleet growth forecast and cost effectiveness analyses for ICAO standards.
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Impacts on Emissions and Fuel Consumption
Passenger Total-ASK
lell
1,7- 	 ICAO
	 PA
1.6
US Domestic: Passenger
3 u
2040

2010
2015
2020
2023
2025
2028
203D
2035
2

2010 2015
2020
2025
Year
2030
2035
2040


2010 2015 2020
2025
Year
2030
2035
2040


2»10
20t*
2620
2023
2025
202*
2O30
2&35
2040

2010
2015
2030
2023
202*
2028
2030
2035
20+0
CAO
1-27E+10

l.ttE+IO



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2 72E+1G

ICAO
i,o»+o»

i.S?E40SI



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EPA

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9.3TE+09
9.B3t-t-09
1.Q2E+10
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1-ioe+io
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1.29E+10

EPA

9.O1E+O0
L11E+09
1.28C+09
13]TE+'09
L53C+D9
1C3E+09
1.H9C+09
2.1iE+C«
TAF

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9.80E+09
lOIC+10
1.05E+-10
110E+10
L14E+10
1236+15
1.32E+10

TM

9.WC+0U
1.21E+09
1.J5H-O0
1+M+09
l.OIt+09
1726+09
1.9M.+&9
2.24E+Q9
Figure 5-3 - Comparison of U.S. Turboprop fleet Available Seat Kilometer of ICAO, EPA and TAF
The U.S. turboprop fleet operations of the three datasets match less well as shown in Figure
5-3. The EPA analysis and TAF are reasonably close while ICAO is about 50 to 100 percent
99

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Impacts on Emissions and Fuel Consumption
higher in ASK. The mismatch is not a major concern for fleet-wide emissions because turboprop
emissions are less than 1% of the overall fleet emissions. The mismatch to ICAO data is even
less of a concern to U.S. emissions since the ICAO dataset is less detailed and less refined for the
U.S. domestic and international operations than the FA A TAF dataset. Since the EPA fleet
evolution results match well with the TAF data, it suggests our fleet evolution results for
turboprop are reasonable, and the emissions and stringency analysis will proceed with the EPA
fleet evolution results on this basis. We intend to resolve this discrepancy with ICAO in the
future.
Regional Jets - ASK
US Domestic: Regional Jets
US International: Regional Jets
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Figure 5-4 - Comparison of U.S. Regional Jet fleet Available Seat Kilometer of ICAO, EPA and TAF
Similar to turboprop, the U.S. regional jet operations of the three datasets match well between
EPA and TAF, but ICAO has about 10% to 30% higher ASK and higher growth rate as shown in
Figure 5-4. This mismatch again is less of a concern for fleet-wide emissions because the
regional jet emissions are a small fraction of the overall passenger fleet emissions. The mismatch
to ICAO data is even less of a concern to U.S. emissions since the ICAO regional jet dataset is
less detailed and less refined than TAF for the U.S. domestic and international operations. Given
that the EPA fleet evolution results match well with the high-fidelity FAA-TAF dataset, the fleet
evolution results for regional jets are fit for purposes of this analysis.
100

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Impacts on Emissions and Fuel Consumption
Freighter - Number of Operations
600000
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Figure 5-5 - Comparison of U.S. Freighter fleet number of operations for ICAO, EPA and TAF
Figure 5-5 shows that the three datasets for freighters are quite different in terms of number of
operations. To compare fleet evolution results for freighter operations from the three datasets,
there are, however, several factors to be considered. These factors are (1) ICAO freighter
operations are exclusively from widebody purpose-built freighters while EPA and TAF include
smaller freighter types, and (2) between EPA and TAF, TAF has more small airplane operations
in its dataset than the EPA analysis, which is based on the FAA 2015 Inventory. Thus, the
higher number of operations in Figure 5-5 does not necessarily translate into higher freight
capacity in terms of ATK (Available Tonne Kilometer) as shown in Figure 5-6. The ICAO
activity dataset we used does not contain payload capacity information, so we can only compare
the EPA analysis with TAF for ATK. It is clear from Figure 5-6 that EPA results match TAF
results closely for U.S. domestic freighter operations. This close agreement, however, is not
observed in the U.S. international freighter operations. In that case, the ATK of TAF is more
than twice the ATK of the EPA analysis because possibly many operations present in TAF are
missing in FAA 2015 Inventory from which the EPA ATK is derived. Figure 5-7 illustrates
some evidence supporting this hypothesis by separating out the operations in TAF with and
without origin-destination (OD) pair, aircraft (AC), and airplane category (CAT) matches to the
EPA analysis (or FAA 2015 Inventory on which the EPA analysis is based). It is clear from
Figure 5-7 that a large part (the top two lines) of TAF U.S. international freight operations has no
matching OD/AC or OD/CAT in the EPA analysis. Given our methodology to use FAA 2015
Inventory as the basis to grow future year activities with TAF growth forecast, this discrepancy
is not critical to our mission to evolve all FAA 2015 Inventory freighter flights into the future for
this EPA analysis. Further reconciliation between TAF and 2015 Inventory is beyond the scope
of this project. For the purpose of this analysis, the EPA fleet evolution results will be used
exclusively for all the further stringency and impact analysis.
US Domestic: Freighter
US International: Freighter
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			Year 				
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101

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Impacts on Emissions and Fuel Consumption
Freighter - ATK
US Domestic: Freighter
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35 -
30-
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US International: Total (GR_Map=F)

— EPA-OD/AC

	 TAF-OD/AC

TAF-OD/AC

(no match)
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TAF-OD/CAT
TAF-OD/CAT
(no match)
2015
2020
2025
2030
2035
2040
Year
Figure 5-7 - Total Available Tonne Kilometer of subsets of flights in EPA and TAF with and without match
origin-destination pair (OD), aircraft type (AC) and airplane category (CAT)
102

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Impacts on Emissions and Fuel Consumption
Business Jet - Number of Operations
3000000
| 275-0000
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Figure 5-8 - Comparison of U.S. Business Jet fleet number of operations for ICAO, EPA and TAF
The business jet operations of ICAO and EPA analyses have similar 2010/2015 base year
operations but different growth rates as shown in Figure 5-8. Comparing to EPA, ICAO appears
to underestimate the growth rate of U.S. domestic business jet operations and overestimate that
of U.S. international business jet operations. Higher growth rate increases the G&R fleet faster
over time, so it tends to amplify the impact of the standards. Conversely, lower growth rate
depresses G&R fleet growth and tends to lower the impact of the standards. Nevertheless, the
effect of this baseline uncertainty is only secondary since the impact of the stringency scenarios,
as measured by the difference from the baseline, would be less sensitive to the baseline
uncertainty. More importantly, the rank order of stringency scenarios in terms of emission
reductions is typically not affected by the uncertainty in baseline. Although the agency
recognizes the problem with the general lack of detailed and reliable growth forecast data
sources for subcategories like turboprop and business jet, we do not believe that uncertainty in
these data would alter any conclusion of the analysis.
5.3.1.1 Conclusions of the Fleet Evolution Results
Overall, the EPA fleet evolution results are acceptable with respect to ICAO and TAF for all
passenger operations in terms of ASK. For turboprop and regional jet operations, ICAO appears
to overestimate the U.S. domestic and U.S. international operations, but the EPA analysis agrees
with TAF in all these operations. For freighter operations, the EPA analysis and TAF have many
small airplanes included, while ICAO is limited to widebody purpose-built freighters only. The
EPA analysis agrees well with TAF in U.S. domestic freighter operations in terms of ATK but
contains significantly fewer operations than TAF in U.S. international freighter operations due to
differences in the base year datasets. For business jet operations, the EPA analysis and ICAO
have similar base year operations but different growth rates, which cause significant differences
in out years. In the absence of more reliable data sources for business jet growth forecast, EPA
will proceed with the current forecast sources from FAA50 and Bombardier '2 for the EPA
US Domestic: Business Jets
US International: Business Jets
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103

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Impacts on Emissions and Fuel Consumption
proposed rule analysis. The uncertainty in the baseline forecast is noted but deemed secondary
for stringency assessment.
5.3.2 Baseline Emissions
The baseline CO2 emissions inventories are estimated in this EPA analysis for 2015, 2020,
2023, 2025, 2028, 2030, 2035, and 2040 using PIANO (the airplane performance model) and the
emissions inventory method described in Chapter 4 along with each year's activities data derived
from the fleet evolution model. The baseline CO2 emissions for global, U.S. total, U.S.
domestic, and U.S. international flights are shown in Figure 5-9 based on outputs from the fleet
evolution model.
In each of the plots contained in Figure 5-9, there are three baselines plotted. These include
the primary analysis (labeled as "CO2") and two sensitivity scenarios (labeled as "CO2 without
continuous improvement" and "frozen fleet assumption"). The top line is the frozen fleet
baseline, which is basically an emission baseline growing at the rate of traffic growth assuming
constant fuel efficiency in the fleet (i.e., no fleet evolution). The second line is the no continuous
improvement baseline where the fuel efficiency of the fleet benefits from the infusion of newer
airplanes from fleet evolution, but the new airplanes entering into the fleet are assumed to be
static and not improving over the entire analysis period (2015-2040). The third line is the
business as usual baseline where the fleet fuel efficiency would benefit from both fleet evolution
with new airplanes entering the fleet and business as usual improvement of the new in-
production airplanes.
These emissions inventory baselines provide a quantitative measure for the effects of model
assumptions on fleet evolution and continuous improvement. The business as usual baseline is
the baseline with all market-driven emissions reduction factors incorporated. It is used as the
primary baseline for this EPA proposed rule analysis. The other two baselines are useful
references for illustrating the effects of fleet evolution and continuous improvement.
Comparing the baselines, the difference between the top two baselines is due to fleet
evolution. Even for G&R airplanes without continuous improvement, the powerful effect of
fleet renewal is clearly evident in emissions inventories of all markets (global, U.S. domestic and
U.S. international). The difference between the bottom two baselines is the effect of continuous
improvement since they have identical fleet evolution.
These baselines are established with no stringency inputs; nevertheless, they provide very
powerful insights into the drivers for emissions inventories and trends. The difference in global
CO2 emissions between the BAU and the frozen fleet baselines in 2040 alone is about 400 Mt, a
huge emissions reduction achievable by market force alone.
It is worth noting that the US domestic market is relatively mature with lower growth rate
than most international markets. This slower growth rate has obvious consequences in the
growth rate of the US domestic CO2 emissions baseline, which is projected with a very slow
growth rate by 2040 given the continuous improvement assumptions.
104

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Impacts on Emissions and Fuel Consumption
— 1500-
1250 -
Global C02
A: fleet turnover w/ cont. imp.
B: fleet turnover w/o cont. imp.
C: frozen fleet
2025 2030
Year
US Total C02
A: fleet turnover w/ cont. imp.
B: fleet turnover w/o cont. imp.
C: frozen fleet
O
U
2025 2030
Year

2015
2020
2023
2025
2028
2030
2035
2040
A
172.44
192.81
202.8
209.01
217.96
223.59
233.67
242.18
B
172.44
193.37
204.04
210.89
221.1
228.05
245.4
264.38
C
172.44
194.52
208.22
217.4
231.68
241.43
267.45
294.82
US Domestic C02
A: fleet turnover w/ cont. imp.
B: fleet turnover w/o cont. imp.
C: frozen fleet
US International C02
e i4o-
o
u
2025 2030
Year

2015
2020
2023
2025
2028
2030
2035
2040
A
105.1
115.19
119.06
121.41
124.99
127.04
129.6
131.85
B
105.1
115.48
119.68
122.38
126.67
129.5
137.15
145.85
C
105.1
117.34
124.29
128.82
135.87
140.56
153.07
167.06
A: fleet turnover w/ cont. imp.
B: fleet turnover w/o cont. imp.
C: frozen fleet
O
u

2015
2020
2025 2030
Year
2035
2040

2015
2020
2023
2025
2028
2030
2035
2040
A
67.33
77.62
83.74
87.6
92.97
96.56
104.07
110.33
B
67.33
77.88
84.36
88.52
94.43
98.55
108.25
118.53
C
67.33
77.18
83.93
88.58
95.81
100.87
114.39
127.76
Figure 5-9 - Range of CO2 emissions baselines with various fleet evolution and continuous improvement
assumptions
5.3.2.1 Discussions on baseline modeling
By modeling fleet evolution variables such as the end-of-production timing and continuous
improvements explicitly, the agency believes that the business as usual baseline would provide a
more accurate assessment of the impacts of the standards on emissions. This comprehensive
model can be a powerful tool to understand the effect of these modelled variables.
One might argue that how fast new technology could infuse into the fleet and how much
market-driven business as usual improvement can be assumed are all inherently uncertain. But
given accurate inputs for fleet evolution and continuous improvement, the baseline inventory can
be better assessed for the real-world performance of all fleets (global, domestic or international).
To help develop this baseline, EPA contracted with ICF to conduct an independent analysis to
develop a credible fleet evolution and technology response forecast58. This ICF analysis
considers both near-term and long-term technological feasibility and market viability of available
technologies and costs for all the modeled G&R airplanes at individual airplane type and family
levels.
105

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Impacts on Emissions and Fuel Consumption
Given these fleet evolution and efficiency improvement estimates, the agency believes that
the emissions inventory baseline so established provides the best possible representation for the
performance of the global and U.S. fleet for assessing the impact of the proposed GHG
standards.
It is traditionally assumed that the baseline does not matter for stringency analysis, because as
the impact of the stringency is measured from stringency to baseline, the effects of baseline
choices tend to cancel out when we consider only the delta of stringency and baseline. It can be
shown that this assumption may not be true when some of the fleet evolution assumptions also
affect the estimates of emission reductions and, thus, change the output of the impact analysis
and potentially influence the policy-making decisions.
In conclusion, using the best possible estimate of a baseline would lead to a more accurate
assessment of the impact of the standards. The effects of fleet evolution, continuous
improvements, and technology responses on emissions inventory and emissions reductions are
discussed further in the following sections.
5.4 Stringency Analysis of U.S. and Global CO2 Emission Impacts
The EPA main analysis includes three stringency scenarios, the proposed standards and two
alternatives. The primary scenario is the proposed GHG standards, which are equivalent to the
ICAO Airplane CO2 Emission Standards. The two alternative scenarios are either a pull-ahead
scenario at the same stringency level as the ICAO in-production standard (Scenario 2) or a pull-
ahead scenario at a higher stringency level comparable to the ICAO new type standard (Scenario
3). See Chapter 6 for a detailed description of the three stringency scenarios, including cost
effectiveness discussions for Scenario 3.
Based on the technology response from the ICF technology and cost report58, there are no
reductions projected in fuel consumption and CO2 emissions for both the primary scenario
(Scenario 1) and the pull-ahead scenario (Scenario 2). This is because all the airplanes in the
G&R fleet either meet the stringency or are out of production when the standards take effect
according to our expected technology responses. Thus, under both scenarios 1 and 2, there
would be no cost and no benefit (no emission reduction) for the proposed GHG standards.
Under Scenario 3, there is one airplane (A380-8) that would be impacted by the stringency.
This airplane, however, is projected to go out of production by 2025 according to ICF's end of
production forecast. Figure 5-10 shows the global CO2 emissions baseline for A380-8 increases
sharply between 2020 and 2025 due to the projected end of production of B747-8 in 2020. After
B747-8 ceases production in 2020, A380-8 takes over part of the B747-8's market share, causing
the sharp increase of baseline A380-8 emissions. After 2025, A380-8 itself also goes out of
production, causing its emissions baseline to decline after 2025 due to normal retirement of the
A380 in the in-service fleet. Slightly below the solid baseline, one can see a dashed line for CO2
emissions of A380 under Scenario 3 between 2025 and 2040. It is less visible between 2023 and
2025, but the table below shows a slight decrease in CO2 emissions for Scenario 3 comparing to
the A380-8 baseline from 2023 to 2040. The sharp reversal of the A380 baseline emissions
inventory is due to the effect of fleet evolution. If we look at the aggregate level of large twin-
aisle (TA_4) market segment to which both A380 and B747 belong, the reversal of the emissions
baseline disappears. The emissions baseline increases monotonically, but the effects of the
106

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Impacts on Emissions and Fuel Consumption
stringency is still faintly visible as the rate of increase slows down a little around 2023-2025 due
to the technology responses of the A380.
| Scenario 3

C02 Emissions - Scenario 3
ACCODE - A380-8
GlOboh A380-8
Market Segment - TA_4
Global: TA 4
Figure 5-10 - CO2 emissions of A380-8 and market segment TA_4 for the baseline and Scenario 3
In summary, the total cumulative CO2 emissions reduction under Scenario 3 for all U.S.
flights (both U.S. domestic and U.S. international) is 1.36 Mega-tonne (Mt), and the reduction
for global flights amounts to 8.16 Mt from 2023 to 2040 as shown below. It is also worth noting
that Scenario 3 has a modest impact (1.24 Mt) on U.S. international emissions but only a very
small impact (0.12 Mt) on U.S. domestic emissions. This is primarily because none of the U.S.
airlines have the A380 in their fleets.
107

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Impacts on Emissions and Fuel Consumption
C02 Cumulative Reduction
2023 2025 2028 2030 2035 2040
1 ¦ 1
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2025
2028
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2035
2040
A
-0.16
-0.98
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-8.16
B
0.0
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-0.04
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-0.08
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C
-0.02
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Figure 5-11 - Cumulative reduction of CO2 emissions from 2023 to 2040 for Scenario 3
5.5 Sensitivity Case Studies
As explained previously, the fleet evolution and continuous improvement assumptions have a
strong influence on the emissions baseline; likewise these assumptions may also have strong
influences on technology responses and subsequently on the emissions reductions. The
following sensitivity studies are designed to help look into these influences and put the results of
the EPA main analysis in perspective.
Among the three scenarios analyzed for this Draft TSD, only Scenario 3 impacts an airplane
and the emission reductions associated with it. The following sensitivity studies will use
Scenario 3 to analyze the effects of these model variables and gain insight of their impacts on
emissions. We then apply the same concept to Scenarios 1 and 2 and discuss the effects of these
variables in a similar manner. Given the evidence from these sensitivity studies, we will
summarize and draw tentative conclusions about potential impacts of this proposed rulemaking.
5.5.1 Scenario 3 Sensitivity to Continuous Improvement
One of the major stringency analysis assumptions is the continuous improvement of in-
production airplanes. We will examine its effect 011 emissions reductions by turning off the
assumption in the EPA main analysis. For reference, we will also compare this analysis with the
corresponding ICAO analysis which, although not directly comparable to EPA main analysis as
explained in section 5.3.1, is an important reference to show the effects of various assumptions in
baseline, fleet evolution, and technology response.
Figure 5-12 shows CO2 emissions of baseline and Scenario 3 for these three cases, i.e., ICAO,
EPA analysis with continuous improvements, and EPA analysis without continuous
108

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Impacts on Emissions and Fuel Consumption
improvements. In the case of U.S. domestic and U.S. international emissions, the ICAO baseline
is about 4% lower than the EPA baselines due to differences in the base year datasets (2010
ICAO COD versus 2015 FAA Inventory). This baseline discrepancy, however, does not affect
the stringency analysis outcome because the emissions reductions are measured relative to the
baseline, and thus they are insensitive to the baseline shift. The emissions reductions, as
measured by the differences between the baselines and stringency lines, are what is important for
resolving the effects of model assumptions in the three cases.
From Figure 5-15, we observe that the emissions reductions increase by more than threefold
when continuous improvement is turned off. For example, the cumulative U.S. total emissions
reductions from 2023 to 2040 for Scenario 3 increase from 1.36 Mt to 4.78 Mt as shown in the
accompanying table in Figure 5-15. These are small compared to the ICAO reduction of 108.99
Mt (38.49 Mt for U.S. Domestic and 70.5 Mt for U.S. International as shown in Figure 5-14) for
the same stringency scenario. This is the reason the EPA Scenario 3 (dashed) lines are almost
indistinguishable from the baselines in Figure 5-12. Examining the zoom-in graph for the A380
in Figure 5-13, however, shows that there are significant emissions reductions for the no
continuous improvement case. This relatively significant amount of reductions for the A380
becomes less significant at the market segment level (the right panel of Figure 5-13). And it is
almost invisible at the total fleet level in Figure 5-12 when the aggregate base becomes
progressively bigger. Nevertheless, the effect of continuous improvement is significant for the
impacted airplane. This result is understandable since the impacted airplane would have to make
larger improvement to meet the stringency from a no continuous improvement baseline, while
the impact of stringency would be a lot smaller if improvements have been made year over year
as assumed by the business as usual baseline. Technically, the two cases achieve the same total
improvement, but one attributes the entire amount of improvement to stringency impact while
the other attributes the business as usual improvement to market force impact and only the
remaining improvement to stringency impact.
It is clear that although the continuous improvement is significant to the impacted airplane,
this factor alone cannot explain the huge differences between the emissions reductions of ICAO
and EPA analyses. We will examine the other important fleet evolution assumption, i.e., the end
of production timing, as a sensitivity study in the next section.
109

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Impacts on Emissions and Fuel
Consumption
Scenario 3
US Domestic: Total
Scenario 3
IffOO
— ICAO Baseline
1600-
— epa Baseline
	 EPA Baseline (w/o Imp. 1
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US International: Total
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KTAO Baseline
EPA Baseline
EPA Baseline (wto imp >
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EPA Scenario 3
EPA Sen, 3 Iw/o imp,)
11

Figure 5-12 - COz Emissions of Baseline and Scenario 3 for ICAO and EPA (w & w/o continuous
improvement) Cases
Zoom In on C02 Emissions of Impacted
Aircraft and Market Segment for Scenario 3
ACCODE - A380-8
Global: A380-8
	 fiasefeie
	 8*wlin<> (w/o imp I
Scenario 3
— Scenario 3 {w/o imp,)
2015
2020
2025
Year
2030
2035
2040


2015
2020
2023
2025
2028
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2035
2040
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2015
2020
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Year
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2035
2040


2015
2020
2023
2025
2028
2030
2035
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U7 62
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197.39
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228.44
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197.23
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Scenario 3 {w/o trnfl.)


198.47
211.62
230.5
244.23
282.78
330.53
Figure 5-13 - Zoom-in Picture of CO2 Emissions of Impacted Airplane A380-8 and Market Segment TA_4 for
EPA Scenario 3 with and without Continuous Improvement
110

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Impacts on Emissions and Fuel Consumption
Scenario 3
Cumulative Reduction
2023
2025
Global: Total
C02 (Mt)
2028 2030 2035
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2040
A
0.0
•0.01
¦0.04
•0.05
¦0.08
¦0.12
B
-0.02
-0.15
-0.38
-0.53
-0.9
-1.24
C
-0.03
-0.16
-0.41
-0.58
-0.98
-1.36
D
-0.01
-0.05
-0.13
-0.17
-0.3
-0.41
E
-0.09
-0.53
-1.33
-1.85
-3.15
-4.37
F
-0.1
-0.58
-1.45
-2.03
-3.45
-4.78
Figure 5-15 - Cumulative U.S. CO2 Reduction for EPA Scenario 3 with & without Continuous Improvement
111

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Impacts on Emissions and Fuel Consumption
5.5.2 Scenario 3 Sensitivity to Extending Production of A380 and B767-3ERF to 2030
Another important fleet evolution variable is the end of production assumption for G&R
airplanes. We will examine the effect of this assumption by extending the end of production of
both A380-8 and B767-3ERF to 2030 from the EPA main analysis' assumption of 2025 and 2023
respectively for the two airplanes in this sensitivity study. The resulting CO2 emissions from this
sensitivity study are shown side by side with the main analysis for A380-8 in Figure 5-16 and for
B767-3ERF in Figure 5-17. Note that Scenario 3 starts to impact A380 in 2023 but not the
B767-3ERF until 2028, due to the 5-year delay in implementation of the standards for
freighters.lxv
A380-8 C02 Emissions
ICF EOP 2025
EOP 2030
Global: A380-B
f

2015
2020
2023
2025
2023
2030
2035 2040
Baseline
27.16
38.31
53.25
65.47
63.32
61.22
53.00 4L36
Scenario 3


53.OS
64.94
62 B
eo.7
52.57 40.69

2015
2020
2023
2025
202S 2030
2035
2040
Baseline
27.16
38.31
53.25
65.47
85 2 99.22
90.6
77.56
Scenano 3


53.08
64.94
84.06 97.62
89.02
76.07
Global: A380-8
	 Baseline
- •- Scenario 3
Figure 5-16 - CO2 emissions of A380-8 with two different end of production (EOP) assumptions (2025 versus
2030) for EPA baseline and Scenario 3
ixv Qn pebruary 14, 2019, Airbus made an announcement to end A380 production by 2021 after Emirates reduced its
A380 order by 39 airplanes and replaced them with A330 and A350. (The Airbus press release is available at:
https://www.airbus.eom/newsroom/press-releases/en/2019/02/airbus-and-emirates-reach-agreement-on-a380-
fleet—sign-new-widebody-orders.html, last accessed on February 10, 2020). The early exit of A380 fits the
general trend of reduced demands for large quad engine airplanes presented in this Draft TSD, but the exact
timing was not expected at the time when our analysis was completed. This latest A380 production information
will affect the modeled results for Scenario 3. Without redoing the whole analysis, we can conclude that the early
exit of A380 would nullify its GHG emission reductions from Scenario 3 since it won't be affected by Scenario
3's implementation date. This result, however, is broadly consistent with our prediction of minimum GHG
reductions for all scenarios, and it does not alter our conclusion of no cost and no benefits for the primary
scenario analyzed in the proposed rule.
112

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Impacts on Emissions and Fuel Consumption
B767-3ERF C02 Emissions
ICF EOP 2023
EOP 2030
Global: B767-3ERF
Global: B767-3ERF
	 baseline
- *- Scenano 3
2025	2030
Year

2015
2020
2023
2025
2028
2030
2035
2040
Baseline
i99
5.83
745
7.19
6.74
6.42
5.64
4.89
Scenario 3


7.45
7.19
6.74
6.42
5.64
489
seine
*- Scenano 3
2025	2030
Year

2015
2020
2023
2025
2028
2030
2035
2040
Baseline
i§9
5.83
7.45
8.78
10.88
13.17
12.36
11.55
Scenano 3


7.45
B.76
10.76
12.68
11.87
11.06
Figure 5-17 - CO2 emissions of B767-3ERF with two different end of production assumptions (2023 versus
2030) for EPA baseline and Scenario 3
It is clear from Figure 5-18 that the cumulative emissions reduction for the extended
production case (right panel of Figure 5-18) is more than 3 times that of the main analysis (left
panel of Figure 5-18). Extending the end of production forecast thus also has a strong effect on
the outcome of the impact analysis (about 3 times in terms of cumulative emissions reductions to
2040).
D
*0
2023
C02 Cumulative Reduction
2025 2028 2030 2035 2040
— 0
c
o
¦II
-4
-6 ¦
-8-
Global
US Domestic
US International
Year
Extended Production: C02 Cumulative Reduction
2023 2025 202B 2030 2035 2040
—
0-
r

0

S



j

•0

-10-
EC

o;
-l"> •
>


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Impacts on Emissions and Fuel Consumption
5.5.3 Scenario 3 Sensitivity to Combined Effects of Continuous Improvement and
Extended Produ ction
Based on the previous two case studies, it is evident that both continuous improvement and
extended production have significant impacts on emissions reductions. Furthermore, these two
important driving factors are independent variables. Thus, in this section we will assess the
combined effects when both extended production and continuous improvement are applied for
Scenario 3.
Figure 5-19 to Figure 5-22 detail the results of this sensitivity study. A key finding of this
sensitivity study is that the effects of continuous improvement and extended production are
largely multiplicative. The two previous sensitivity studies have shown that the extended
production and the lack of continuous improvement each produced about 3 times the emissions
reductions of the EPA main analysis. As shown in Figure 5-21, the ratio of emissions reduction
impact between with and without continuous improvements is again about 3 times (e.g., 29.3 Mt
versus 87.34 Mt for the cumulative global CO2 reduction to 2040). The combined effects of
extended production and continuous improvement increase the ratio of emissions reductions to
more than 10 times (e.g., 87.34 Mt (Figure 5-21) versus 8.16 Mt (Figure 5-14) for the cumulative
global CO2 reduction to 2040).
Zoom In on C02 Emissions of Impacted
Aircraft and Market Segment for Scenario 3
ACCODE - A380-8
Global; A3SO-8
100 	 Baseline ItP)
^ — Baseline If P. nto imp.)
Scenario 3 (EP|
80 — Scenario 3 (EP. w/o imp. I
£
8
2D4D
Year

>015
2020
2023
2025
AJ2B
2030
2035
2040
Basefcne 
26.89
37.59
51.55
62.92
81.46
94.76
86.3
73.66
Basefene {EP, w/o lmp.>
26.89
37.77
52.37
64.44
84.52
99.18
90.64
77.76
Scenario 3 IEPI


51.39
62.42
80.41
93.25
84.82
72.25
Scenarw 3IEP w/o Mr®,)


51.81
62 69
80 74
93.87
85 41
72.79
Market Segment - TA_4
Global: TA_4
350
	 Baseline IIP)
	 Baseline If P, Ufa imp.)
Scenario 3 CEPI
— Scenario 3 (EP. w/o imp. I
325
300
~ 250
8 "5
175
150
2015
Year

2015
2020
2023
2025
2J2S
2030
2035
20*0
Base&ne 
147.62
178.64
199,03
213.37
237.24
254.79
293.18
340.5
Scenario 3 fEP)


197.23
210.27
231.45
246.61
280.76
321.56
Scerwrw 3 IEP. wfo imp. i


196.47
211.62
23346
249 49
287 95
335.53
Figure 5-19 - Zoom-in view of CO2 Emissions of A380-8 and Market Segment TA_4, for Extended
Production to 2030, with and without Continuous Improvement
114

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Impacts on Emissions and Fuel Consumption
Zoom In on C02 Emissions of Impacted
Aircraft and Market Segment for Scenario 3
ACCODE - B767-3ERF
Global: B767-3ERF
Baseline CEPI
Baseline (EP. wto imp J
Scenano i IEP)
Scenario 3 IEP. w/o imp.)
Market Segment - FR
Global: FR
fesolin e
Baseline (EP. wfo imp.)
Scenario 3 (EP)
Scenario 3 (EP, w/o imp. I
2015
2020
2025
Year
2030
2035
2040
2015
2020
2025
Vear
2030
2035
2040

2015
2020
2023
2025
2028
2030
2035
2040

2015
2020
2023
2025
2023
2030
2035
2G40
Baseline I EPI
3.99
6.56
3.05
10.7
13.65
16.9
16.06
15.18

Baseline I EP}
36.36
42.25
47.43
51.46
57.9
62.34
75.36
90.43
Baseline IEP. w/o imp.)
399
6.6
8 99
10.95
14.12
17 €7
16,82
15.93

Baseline IEP. vita imp.)
36.36
42.39
47.77
52.03
53.96
63.87
78.13
95.0
Scenario 3 (EP)


8.85
10.7
13.43
1622
15.39
14.51

Scenario 3 IIP)


47,43
53.48
57,73
61,66
iA «9
B9.&1
Scenano 3 (EP. wto imp 1


399
10 95
13.86
16 56
15.75
14.36

5**nario 3 IEP. w/o imp.)


47.7?
52.03
¦XI.69
62,78
77 05
93.93
Figure 5-20 - Zoom-in view of CO2 Emissions of B767-3ERF and Market Segment FR, for Extended
Production to 2030, with and without Continuous Improvement
Scenario 3
Cumulative Reduction
Global: Total
C02 (Mt)
2023
2025
2028
2030
2035
2040
-100-
ICAO Cum. Reduction
EPA Cum. Reduction (EP)
-200 n EPA Cum. Red. (EP, w/o imp.)
-300-
-400-
-500
-600 •
Year

2023
2025
2028
2030
2035
2040
ICAO



-122.87

*64.22
EPA (EP>
•0.16
-0.98
-3.96
-7.86
18.72
-29.3
EPA (EP. w/o imp.)
-0.56
-3.46
-13.3
-24.9
-56.6
•87.34
2025
U5 Domestic: Total
C02 (Mt)
2028
ICAO Curn. Reduction
EPA Cum. Reduction IEPI
EPA Cum. Red fEP. wto Imp.)
£ -30-

2023
2025
2028
2030
2i335
2040
\CAO



-6.7

SB 49
EPA IEP)
0.0
O.01
£.09
0.26
¦0.78
1.29
£PA(£P, w/o imp-|
¦0.01
-0.05
4)24
-0.59
-1.59
-2 5a
US International: Total
C02 (Mt)
JH23 2023 2028 2030 2035
I ICAD Cum. Reduction
i EPA Cum. Reduction )£P)
i EPA Cum. Red. (EP. wrt> imp.)

2023
2025
2028
2030
2015
2040
ICAO



14.2.T

-3.B3
12.07 '
EPA (EP)
¦0.02
4.15
0.58
¦ 1.08
2.4?
EPA (EP, wi'o imp.)
-0.09
4.53
L97
3.55
7.38
Figure 5-21 - Cumulative COz Reduction of Scenario 3 for ICAO and EPA (Sensitivity Study of Extended
Production to 2030 for A380 and B767F, with & without continuous improvement)
115

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Impacts on Emissions and Fuel Consumption
Scenario 3: U.S. C02 Cumulative Reduction
Extended Production: U. S. C02 Cumulative Reduction
jj	2023 2025 2028 2030 2035 2040
®	Hi A: US Domestic (EP)
0)	-7.5-	Mi B: US International (EP)
B	¦¦ C: US Total (EP)
¦5	~10-0	« D: US Domestic (EP, wlo imp,)
|	12 5	!¦ E; US InternationaHEP. w/o imp.)
u	J	F: US TotaHEP, w/o imp.)
8	Year

2023
2025
2028
2030
2035
2040
A
0.0
¦0,01
¦0,09
¦0,26
-0,78
-1.29
B
-0.02
-0.15
-0.53
-1.08
-2.47
-3.82
c
-0.03
-0,16
-0.67
-1.34
-3,25
-5.11
D
-0.01
-0.05
-0-24
-0.59
-1.59
-2.58
E
-0,09
-0.53
-1-97
-3.55
-7.B8
-12.07
F
-O.l
-0.58
-2.21
-4.14
-9.47
-14.65
Figure 5 22 - Cumulative U.S. CO2 Reduction of Scenario 3 for the Sensitivity Study of Extended Production
to 2030 for A380 and B767F, with & without continuous improvement
Extrapolating this finding further, we can clearly see that the projected emissions reductions
can be increased even more by extending the production of current in-production airplanes
further into the future. ICAO's analysis assumed no end of production for current in-production
airplanes. This explains why significantly higher emissions reductions were found in the ICAO
analysis compared to the EPA analysis for the same stringency scenario. The key is in fleet
evolution, technology response, and baseline assumptions. Thus, it is crucial to establish the best
possible estimates for fleet evolution, technology response, and business as usual baseline to
provide a more accurate assessment for the costs and benefits of the proposed standards.
5.5.4 Similar Sensitivity Studies for Scenarios 1 and 2
In summary, the sensitivity studies for Scenario 3 show that the EPA and ICAO analyses of
emissions reductions, although quite different, are results of their respective model assumptions.
As we relax the assumptions in the EPA analysis to be more like ICAO's, the results tend toward
ICAO results. It will eventually reproduce ICAO results when given the same model
assumptions. We also evaluated whether this trend would hold true for Scenarios 1 and 2. We
analyzed emissions reductions for Scenarios 1 and 2 under various model assumptions similar to
what was done in previous sections for Scenario 3. Like the sensitivity studies for Scenario 3,
only A380 and 767-3ERF are considered since they are the only airplanes potentially impacted
by the proposed standards and alternative scenarios.
Specifically, without continuous improvement (CI), the A380 would not pass the proposed in-
production standards and would need to make about 1% improvements to be compliant and 2%
improvements with the 1% design margin. This is true for both Scenarios 1 and 2 since without
116

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Impacts on Emissions and Fuel Consumption
CI, the metric value margin to the stringency line would not change with time and required
improvements would remain the same independent of the standards effective dates. With CI,
A380 would pass the proposed standards in both 2023 and 2028 timeframes and does not require
any additional improvement for Scenarios 1 and 2.
On the other hand, 767-3ERF would not pass the proposed in-production standards with or
without CI, so its response status is mostly driven by the end of production assumption. In other
words, in the normal assumption of end of production in 2023, there would be no need to
improve in either Scenarios 1 or 2 with the standards effective date for freighters starting in
2028. In the extended production case, 767-3ERF would have a 3-year window from 2028 to
2030 that it would need to improve to be compliant with the proposed in-production standards.
Scenario 3 Sensitivity Studies
|
Th'/o CI	LP	LP 4 w/<
ScefurloB
0
-1DO
-200
-SOT
fiCO
-500
-600
-TOO
¦ ttbbal ¦UiLlom HiAIr* *115. lota*
Scenario 1 Sensitivity Studies
Es-t.
w/o CI EP EP a w/o CI U
-LQ0

Scerarti i
-20O





•SOD
-700



¦ Global «U5ft>-n «U51ty1 "USToIsi
Comparing Sensitivity of Emission Reduction
Estimates to Model Assumptions Between
EPA and "ICAO-like" Analyses, Including
Three Intermediate Case Studies for
Scenarios 1, 2, and 3:
*	Without Continuous Improvement (w/o CI)
*	Extended Production (EP)
*	Combination of the Two Assumptions (EP &
w/o CI)
Scenario 2 Sensitivity Studies
	m
w/o CI	EP	e:-a w/o ci
Sce^r^ 2
B"|
Q
-1C0
-3CQ
-3C0
-«a
-KG
-eca
-70(3
¦ •Slab*! ¦uLDotYi luSk-Yi ¦U&Toatf
Figure 5-23 - Summary of Sensitivity to Model Assumptions for Scenarios 1, 2 and 3
To put the sensitivity studies in context and compare the general trends for all three scenarios,
we will examine the five cases in each scenario as shown in Figure 5-23. A brief discussion of
the five sensitivity cases is given below.
1.
2.
Case 1 (EPA): For the EPA analysis, both Scenarios 1 and 2 show no emissions reduction,
due to the continuous improvement assumption for A380 and the end-of-production
assumption (2023) for 767-3ERF.
Case 2 (w/o CI): In the case of without continuous improvement, Scenario 1 would still be no
emissions reduction because A380 would be out of production by 2025. Scenario 2, however
would produce a small benefit of 2% fuel efficiency improvement from A380 between the
117

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Impacts on Emissions and Fuel Consumption
pull-ahead schedule of 2023 and the end-of-production year of 2025. The CO2 reduction
would be on the order of 6 Mt globally and 1 Mt in U.S. total for Scenario 2.
3.	Case 3 (EP): In the case of extended production (EP) with continuous improvement, the
benefit would all come from 767-3ERF since A380 would be compliant with the proposed
in-production standards with continuous improvement. Since the pull-ahead schedule is not
assumed for freighters, Scenarios 1 and 2 are the same and the estimated CO2 reduction
would be on the order of 4 Mt globally and 1 Mt in U.S. total.
4.	Case 4 (EP & w/o CI): In the case of extended production without continuous improvement,
Scenario 1 would be benefitted by 3 years of improvement from A380 and 767-3ERF in
2028-2030 and larger improvements required from no continuous improvement
baselines. Scenario 2 would be similar except that the A380 benefit would be from the pull-
ahead schedule of 2023. The rough estimate of emissions reductions for Scenario 1 would be
14 Mt globally and 3 Mt in U.S. total and for Scenario 2, 24 Mt globally and 4 Mt in U.S.
total.
5.	Case 5 (ICAO-like): The ICAO like CO2 reductions have been analyzed previously as 249.75
Mt globally and 45.52 Mt in U.S. total for Scenario 1, and 412.44 Mt globally and 74.82 in
U.S. total for Scenario 2.
Given this sensitivity analysis, we can conclude that the technology response and fleet
evolution (principally continuous improvement and end of production) assumptions drive the
difference between EPA and ICAO analyses. Also, as in Scenario 3, as we modify the
continuous improvement (CI) and extended production (EP) assumptions in Scenarios 1 and 2 to
be closer to that of the ICAO analysis, the emissions reductions results move progressively
closer to ICAO results. These general trends of emissions reductions from EPA analysis to
ICAO analysis for Scenarios 1, 2 and 3 are shown in Figure 5-23.
Although uncertainties around these model assumptions exist, the sensitivity studies clearly
show that even when we remove the continuous improvement assumption and extend the
production of A380 and 767-3ERF to 2030, the emissions reductions for all three scenarios are
still quite modest and in all cases are an order of magnitude smaller than that of the ICAO-like
analysis. Both assumptions of no improvement for 20 years and extending production of current
airplane models indefinitely into the future are highly unlikely to happen in the real world. On
the other hand, the business as usual baseline and the independently developed and peer
reviewed technology response help estimate the true impact of the standards. In terms of
modeling, the agency attributes the business as usual improvements to market competition while
ICAO treats them as part of the impacts from the standards. Both are valid with respect to their
model assumptions.
In summary, the EPA analysis shows the proposed GHG standards, which match the ICAO
Airplane CO2 Emission Standards, have no cost or benefit in Scenarios 1 and 2 but produce a
small environmental benefit (1.4 Mt CO2 reductions in the U.S.) in Scenario 3 that is not enough
to justify deviating from the international standards. Therefore, the agency proposes to match
the U.S. airplane GHG standards with the ICAO Airplane CO2 Emission Standards. These
harmonized standards would enable U.S. airplane and engine manufacturers to compete
internationally on a level playing field. Chapter 6 provides further discussions on EPA's
rationale for this proposed standard.
118

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Impacts on Emissions and Fuel Consumption
REFERENCES
58ICF, 2018: Aircraft COi Cost and Technology Refresh and Industry Characterization, Final Report, EPA Contract
Number EP-C-16-020, September 30, 2018.
119

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Analysis of Alternatives
Table of Contents
Chapter 6 Analysis of Alternatives	121
6.1	Overview	121
6.1.1	ICAO/CAEP Stringency Options, International Standards Adopted, and Proposed
Standards	121
6.1.2	Alternatives Considered in the Context of CAEP Stringency Options, International
Standards Adopted, and Proposed Standards	126
6.2	GHG Emission Reductions and Costs of Two Alternative Scenarios	132
6.2.1	Scenario 2	132
6.2.2	Scenario 3	133
6.2.2.1	767-3ERF	134
6.2.2.2	A380	 134
6.2.2.2.1	A380's GHG Emission Reductions	136
6.2.2.2.2	A380's Costs	136
6.2.2.3	Monetized Benefits for A380	 137
6.3	Sensitivity Case Studies	144
6.3.1	Emission Reductions for Scenario 3	144
6.3.2	Emission Reductions for Scenarios 1 and 2	144
6.3.3	Costs for All Three Scenarios	145
6.4	Summary	146
Table of Figures
Figure 6-1 - Proposed GHG Emission Standards and CAEP's Ten Stringency Options (MTOM in kilograms)	125
Figure 6-2 - Proposed GHG Emission Standards and CAEP's Ten Stringency Options	126
Figure 6-3 - In-Production Airplane Stringency Lines for the Three	131
Figure 6-4 - Detail of In-Production Airplane Stringency Lines for Airplane Below 100 tons MTOM	132
Figure 6-5 - A380 Incremental Improvement Technology Supply Curve	136
Table of Tables
Table 6-1 - Coefficients Used in Equation for Ten CAEP Stringency Options	122
Table 6-2 - Percentage Differences Between the Ten CAEP Stringency	122
Table 6-3 - Stringency Levels and Effective Dates for Proposed GHG Emission Standards	124
Table 6-4 - Proposed Rule and Alternative Scenarios	128
Table 6-5 - A380 Scenario 3 - Implementation of Technology Response	135
Table 6-6 - Interim Domestic Social Cost of CO2, 2015-2050 (in 2015$ per metric ton)*	138
Table 6-7 - Interim Domestic Social Cost of N2O, 2015-2050 (in 2015$ per metric ton)*	138
Table 6-8 - Detailed Domestic C02-Related Benefits for Scenario 3- (Millions of 2015$)	140
Table 6-9 - Detailed Domestic N20-Related Benefits for Scenario 3 (Millions of 2015$)	141
Table 6-10 - Detailed Domestic Fuel Savings for Scenario 3 (Millions of 2015$)	142
Table 6-11 - Summary of Domestic Climate-Related Benefits and Fuel Savings for Scenario 3	142
Table 6-12 - Summary of Domestic Climate-Related Benefits and Fuel Savings for Scenario 3	143
Table of Equations
Equation 6-1 - Calculation of Metric Values for Ten CAEP Stringency Options	122
120

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Analysis of Alternatives
Chapter 6 Analysis of Alternatives
This chapter describes the three scenarios, including the two alternative scenarios, that the
EPA analyzed, and it discusses the costs, emission reductions, and benefits of these alternative
scenarios. The agency's methodologies for assessing technological feasibility, costs, and
emission reductions were described earlier in Chapter 2, Chapter 4, and Chapter 5. The same
methodologies were used to analyze the proposed GHG standards and two alternative scenarios.
6.1 Overview
To give context to the alternative scenarios analyzed by the EPA, we will first provide
background on the stringency options considered by ICAO/CAEP in developing the international
Airplane CO2 Emission Standards. We then describe the alternative scenarios in detail.
6.1.1 ICAO/CAEP Stringency Options. International Standards Adopted, and Proposed
Standards
As described in the 2015 ANPR, for the international Airplane CO2 Emission Standards,
CAEP analyzed 10 different stringency options (SOs) lxvi for standards of both in-production and
new type design airplanes, comparing airplanes with a similar level of technology on the same
stringency level.59 These stringency options were generically referred to numerically from "1"
as the least stringent to "10" as the most stringent. The 2015 ANPR described the range of
stringency options under consideration at ICAO/CAEP as falling into three categories as follows:
(1) CO2 stringency options that could impactlxvu only the oldest, least efficient airplanes in-
production around the world, (2) middle range CO2 stringency options that could impact many
airplanes currently in-production and comprising much of the current operational fleet, and (3)
CO2 stringency options that could impact airplanes that have either just entered production or are
in final design phase but would be in-production by the time the international Airplane CO2
Emission Standards become effective.1
In addition, these ten stringency options are described in the report of the CAEP meeting in
February 2016.60 The equation for the ten SOs (or the equation to calculate the SOs' metric
values (MVs)) and the accompanying coefficients that determine each of the distinct SOs are
provided below in Equation 6-1 and Table 6-1. Equation 6-1 is a second order log curve where
the coefficients were derived to match the trends of MVs for airplanes. Table 6-1 shows that
there was a kink point at 60,000 kilograms MTOM for each of the ten stringency options. The
percentage differences between SOs, which are shown in Table 6-2 below, were not constant
because CAEP's intent was for the SOs to affect the full scope of in-production and in-
development airplanes as the SOs increased in stringency.1™11 The CAEP report indicated that
lxvl In this chapter, generally the term, "stringency option" will be used to describe the ten ICAO/CAEP's stringency
options, and the term, "stringency level" will be used to describe the proposed GHG standards, which match the
international Airplane CO2 Emission Standards that were agreed to by CAEP in February 2016.
lxvu As described in the 2015 ANPR, the airplanes shown in Figures 6-1 and 6-2 are in-production and current in-
development. These airplanes could be impacted by in-production standards in that, if they were above the
standards, they would need to either implement a technology response or go out of production. For standards for
only new type designs, there would be no regulatory requirement for these airplanes to respond,
lxvm "jn Development" airplanes are the airplanes that were in development by manufacturers at the time of the
CAEP cost-effectiveness analysis and the publication of the 2015 ANPR.
121

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Analysis of Alternatives
the ten SOs provided a convenient analytical space to perform a cost-effectiveness analysis, but
these SOs had no particular meaning for the stringencies ultimately agreed upon at CAEP for the
international Airplane CO2 Emission Standards.
Equation 6-1 - Calculation of Metric Values for Ten CAEP Stringency Options
MV = 10 (CO + CI * loglO(MTOM) + C2 * (loglO(MTOM))2)
Table 6-1 - Coefficients Used in Equation for Ten CAEP Stringency Options
Coefficients
SOI
S02
S03
S04
S05
S06
S07
S08
S09
SO10

C2
-0.00129488
-0.0111115
-0.0191302
-0.0233739
-0.0277861
-0.0323773
-0.0371585
-0.0409071
-0.0409071
-0.0409071
Below 60t
CI
0.4623490
0.5434880
0.6097660
0.6448410
0.6813100
0.7192570
0.7587750
0.7897580
0.7897580
0.7897580

CO
-2.23839
-2.42424
-2.57535
-2.65507
-2.73780
-2.82370
-2.91298
-2.98395
-3.00564
-3.02627
MTOM at kink point
60000
60000
60000
60000
60000
60000
60000
60000
60000
60000

C2
0.0593831
0.0593831
0.0593831
0.0593831
0.0593831
0.0593831
0.0593831
0.0593831
0.0593831
0.0593831
Above 60t
CI
-0.0205170
-0.0205170
-0.0205170
-0.0205170
-0.0205170
-0.0205170
-0.0205170
-0.0205170
-0.0205170
-0.0205170

CO
-1.31651
-1.33879
-1.35628
-1.36529
-1.37450
-1.38391
-1.39353
-1.40203
-1.42372
-1.44435
Table 6-2 - Percentage Differences Between the Ten CAEP Stringency
CAEP CO2 Stringency
Option
% Difference to SOI
at 60t MTOM
% Difference to
Previous SO at 60t
MTOM
MV at 60t
MTOM
1
-
--
0.8734
2
-5.0%
-5.0%
0.8297
3
-8.7%
-3.9%
0.797
4
-10.6%
-2.1%
0.7806
5
-12.5%
-2.1%
0.7642
6
-14.4%
-2.1%
0.7479
7
-16.2%
-2.2%
0.7315
8
-17.9%
-1.9%
0.7173
9
-21.9%
-4.9%
0.6823
10
-25.5%
-4.6%
0.6507
At this February 2016 meeting, CAEP agreed on an initial set of international standards to
regulate CO2 emissions from airplanes, and the proposed GHG standards match these
international standards. It was agreed that these international standards should apply to both new
type design and in-production airplanes. The effective date for the in-production standards were
agreed to be later than for the standards for new type designs. This would allow manufacturers
and certification authorities additional preparation time to accommodate the standards. The
standards for smaller and larger new type design and in-production airplanes were agreed to be
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set at different stringencies to reflect the range of technology being used and the availability of
new fuel burn reduction technologies that vary across airplanes of differing size and weight. The
proposed standards and associated effective dates match these provisions for the international
standards. Table 6-3 provides a brief overview of the effective dates and stringency levels (SL)
of the proposed standards, which are equivalent to the international standards, including the
standards' equations and associated coefficients (as described earlier in Equation 6-1 and Table
6-1). As described earlier, CAEP considered and analyzed 10 different stringency options for
standards of both in-production and new type designs (from 1 as the least stringent to 10 as the
most stringent). Ultimately, CAEP agreed upon the international Airplane CO2 Emission
Standards with a SL8.5 for new type design airplanes greater than about 70,000 kilograms
MTOM, which the proposed standards match for this applicability criteria, and this SL8.5 is
between CAEP's S08 and S09 (described earlier). There is a difference in the shape of lines for
the ten CAEP SOs compared to the proposed standards. This difference is due to the kink point
at 60,000 kilograms MTOM for the ten CAEP SOs versus the horizontal transition between
60,000 and about 70,000 kilograms MTOM for the proposed standards (which are equivalent to
the international standards), as described further below.lxix
lxlx When analyzing stringency options, CAEP determined that there were significant performance differences
between large and small airplanes. Airplanes with an MTOM less than 60,000 kilograms are either business jets
or regional jets. Due to the physical size of smaller airplanes, there are scaling challenges which limit technology
improvements on smaller airplanes compared to larger airplanes. This leads to requiring higher capital costs to
implement the technology relative to the sale price of the airplanes. Business jets (generally less than 60,000
kilograms MTOM) tend to operate differently than commercial airplanes by flying at higher altitudes and faster
than commercial traffic. Based on these considerations, when developing stringency options for the international
standard, ICAO further realized that curve shapes of the data differed for large and small airplanes (on MTOM
versus metric value plots). Looking at the dataset, there was originally a gap in the data at 60,000 kilograms.
This natural gap allowed a kink point to be established between larger commercial airplanes and smaller business
jets and regional jets. The kink point provided flexibility at CAEP to consider standards at appropriate levels for
airplanes above and below 60,000 kilograms. (This kink point accommodates a change in slope observed
between large and small airplanes.) The flat section of the curve starting at 60,000 kilograms, for the stringency
options, is used as a transition to connect the curves for larger and smaller airplanes.
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Table 6-3 - Stringency Levels and Effective Dates for Proposed GHG Emission Standards

Airplane Weight
(MTOM) Thresholds
(KG)
New-Type Airplane
Maximum Permitted
GHG Level
In-Production
Airplane Maximum
Permitted GHG
Level
Stringency Level
>5,700 to <60,000
SL5
a
SL3
A

Horizontal Transition1™
SL5-SL8.5lxxi
SL3-SL7lxxii

60,000 to ~ 70,000
c
D

> -70,000
SL8.5
e
SL7
F
Implementation Date
Application for a new-
type certificate or a
change to an existing-
type certificate
2020
(2023 for planes with
less than 19 seats)
2023

Production Cut-Off
n/a
2028
a.	Equation of Stringency Level #5: MV = i0"2-73780+ (0 681310 *	(-0.0277861. (iogio(MTOM))2)
b.	Equation of Stringency Level #3: MV = 10"2-57535 + (0-609766. ,oflio(Mr0M))+ (-0.0191302«((oflio(Mr0M))2)
c.	Equation of New Type transition - 60,000 to 70,395kg: MV = 0. 764
d.	Equation of In-production transition - 60,000 to 70,107kg: MV = 0.797
e.	Equation of Stringency Level #8.5: MV = 10~1A12742 + (-0 020517. iogioiMTOM))+ (0.0593831. (iogmMTOM)f)
f.	Equation of Stringency Level #7: MV = 10"139353 + M-020517 .iogW(.MTOM))+ (0.0593831. (iogio(MTOM)f)
Figure 6-1 and Figure 6-2 show a graphical depiction of both the proposed standards for new
type design and in-production airplanes compared against the 10 CAEP stringency options
(described earlier) and the CO2 metric values (as of February 2017) of in-production and in-
developmentlxxm airplanes. As described in earlier chapters of this Draft TSD, the airplane
metric value data shown were generated by the EPA using a commercially available airplane
modeling tool called PIANO (PIANO version 5.4, dated February 2017).61 Note, a number of
the airplanes currently shown as in-production are expected to go out of production and be
lxx Stringency lines above and below 60,000 kilograms (MTOM) are connected by a horizontal transition starting at
60,000 kilograms (MTOM) and continuing right (increasing mass) until it intersects with the next level.
lxxl The stringency level for the standards starting at 60,000 kilograms maintains the level of SL5 until it intersects
the SL8.5 at 70,395 kilograms (MTOM).
lxx 11 stringency level for the standards starting at 60,000 kilograms maintains the level of SL3 until it intersects
SL7 at 70,107 kilograms (MTOM).
lxx in Airpianes that are currently in-development but will be in production by the applicability dates. These could be
new type design or significant partial redesigned airplanes.
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Analysis of Alternatives
replaced by known in development airplanes prior to both the proposed GHG standards for new
type design and the in-production airplanes going into effect.
SOS
S09
SO10
In-Productiori
New Type
Piano MV
MTOM (1000 kg)
Figure 6-1 - Proposed GHG Emission Standards and CAEP's Ten Stringency Options (MTOM in
kilograms)lxxiv
lxxiv jn iegenc[ of Figure 6-1 and Figure 6-2, "In-Production" and "New Type" refer to the graphical depiction of
the proposed standards for in-production and new type design airplanes, and the international standards agreed to
at the February 2016 CAEP meeting match these proposed standards.
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Analysis of Alternatives
1.0
0,8

0.6
u
¦4—J
CU
S
0.4
0.2
0.0
0	20	40	60	80	100
MTOM (1000 kg)
Figure 6-2 - Proposed GHG Emission Standards and CAEP's Ten Stringency Options
(Zoomed to show <100,000 MTOM in kilograms)
6.1.2 Alternatives Considered in the Context of CAEP Stringency Options. International
Standards Adopted, and Proposed Standards
As discussed earlier, in the EPA consideration of alternative scenarios, the proposed GHG
standards, which match the international standards, are designated as the primary scenario,
identified as Scenario 1 (described earlier in Table 6-3). The alternative scenarios considered the
earlier implementation dates and more stringent levels (or more stringent options) that CAEP
analyzed. The two alternative scenarios, identified as Scenarios 2 and 3, were defined to
consider whether moving the implementation date(s) forward (for in-production airplanes) and
tightening the stringency (for both in production and new type designs) would make a
meaningful difference.lxxv Scenario 2 reflects the earliest implementation date that is practical,
and Scenario 3 represents the most stringent option analyzed by CAEP. All three scenarios are
summarized below in Table 6-4, and all three scenarios are assessed against the (no regulation)
lxxv p^s described earlier, CAEP analyzed stringency options that were less stringent than the standards ICAO
ultimately adopted. As discussed in section II.D. of the Federal Register Notice for this proposed rule, under the
Chicago Convention, we are obligated to adopt standards that are at least as stringent as ICAO standards. Thus,
the EPA did not analyze any CAEP stringency options that are less stringent than the ICAO standards.
—	SOS
SO 9
—	SOlO
—	In-Production
-- New Type
• Piano MV
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Analysis of Alternatives
baseline that assumes continuous (2016-2040) annual fuel efficiency improvements and end of
production timing (for some in-production airplanes) —as described in Chapter 5. As described
earlier, for smaller and larger airplanes, under all three scenarios, the stringencies for new type
design and in-production airplanes are assumed to be set at different levels to reflect the range of
technology being used and the availability of new fuel burn reduction technologies that vary
across airplanes of differing size and MTOM.
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Analysis of Alternatives
Table 6-4 - Proposed Rule and Alternative Scenarios
Scenario
Option
Description of Stringency and Effective Date
1
Proposed Rule
(see Table 6-3
above)
-New Tvpe: SL8.5, 2020
(SL5, 2023 for new type airplanes < 60 tonslxxvi,lxxvu & < 19
seats)
-In-Production: SL7 (5% less stringent vs. new tvpe),
2028lxxviii
(SL3, 4% less stringent vs. new type, 2028 also for in-
production airplanes < 60 tons and dedicated freighters)
(2023 for GHG adverse or significant In-Production type
changes)
2
Pull Ahead Some
In-Production
Dates
-New Tvpe: Same stringencies and same effective dates for
New Type as Scenario 1
-In-Production: Differentiate In-Production effective dates and
move general effective date to 2023
(move in-production airplanes < 60 tons effective date to 2025,
but retain 2028 effective date for in-production dedicated
freighters)
3
Pull Ahead Some
New Type and In-
Production
Dates and More
Stringent
Levels
-New Tvpe: Similar to ICAO S09. 2.5% more stringent than
Scenario l's SL8.5
(Matches ICAO S06, 2% more stringent than Scenario l's
SL5 and 2020 for airplanes < 60 tons)
-In-Production: Similar to ICAO S08 or S09lxxix, 2% to 7%
more stringent than Scenario l's SL7 lxxx and move effective
date to 2023
(Matches ICAO S05, 3% to 4% more stringent than Scenario
l's SL3 for in-production airplanes <60 tons and move
effective date to 2025, but retain 2028 effective date for in-
production dedicated freighters)
lxxvl In this rulemaking, 60 tons means 60 metric tons, which is equal to 60,000 kilograms (kg). Or, 1 ton means 1
metric ton, which is equal to 1,000 kg.
lxxvn por new type design airplanes and in-production airplanes, the MTOM thresholds for covered airplanes are
as follows: greater than 5.7 tons (or 5,700 kilograms) MTOM for subsonic jet airplanes and greater than 8.618
tons (8,618 kilograms) MTOM for turboprop airplanes,
lxxvm por Scenarios 1 and 2, the 19-seat differentiation (for airplanes less than or equal to 60 tons MTOM) in
effective date only applies to new type design airplanes.
lxxD! Scenario 3 includes two stringency options, ICAO S08 and S09, for in-production airplanes greater than 60
tons MTOM.
lxxx For Scenario 3, its more stringent levels also apply to dedicated freighters (including dedicated freighters less
than or equal to 60 tons MTOM), but the 2028 in-production effective date is retained for dedicated freighters.
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Analysis of Alternatives
Scenario 2 considers whether an earlier implementation date for the proposed GHG standards
would result in benefits that outweigh the costs. Scenario 2 would have the same stringencies as
Scenario 1 (and the proposed standards, which match the international standards). However, in
contrast to Scenario 1 where the standards would only become effective on or after January 1,
2023, for GHG adverse or significant in-production type changes,lxxxi Scenario 2 would have this
same effective date for most in-production airplanes, which is five years earlier than Scenario
1	_ixxxii earjjer effective date for Scenario 2 is based on expected improvements to airplanes
and changes in their production status in the next five years. For in-production airplanes that are
60 tons or less MTOM, the Scenario 2 effective date is assumed to be moved to 2025, which is
three years earlier than Scenario 1. Flexibility is provided for airplanes that are 60 tons or less
MTOM because these smaller airplanes have limited technologies available to incorporate in
comparison to larger airplanes (mainly larger passenger commercial airplanes), and smaller
airplanes have different economic viability of technology development relative to larger
airplanes.lxxxm But for dedicated freighters, the Scenario 2 effective date would remain the same
as Scenario 1 (January 1, 2028). Flexibility is provided for these dedicated freighters in Scenario
2	because of the unique aspects of the market for commercial air cargo transport — e.g., the small
size of the market for air cargo transport services and the potentially limited business case for
making improvements to these airplanes.lxxxiv
Scenario 3 considers more stringent standards in addition to an earlier implementation date for
new type design airplanes that are 60 tons or less MTOM and 19 seats or less (in maximum
passenger seating capacity) and the same earlier effective dates for in-production airplanes
considered in Scenario 2. Similar to Scenario 2, Scenario 3 has a January 1, 2023, effective date
(five years earlier than Scenario 1) for in-production airplanes in general, a January 1, 2025,
effective date for in-production airplanes that are 60 tons or less MTOM, and a January 1, 2028,
effective date for in-production airplanes that are dedicated freighters. In addition, Scenario 3
would have more stringent standards for both new type design and in-production airplanes
compared to Scenarios 1 and 2. For new type design airplanes greater than 60 tons MTOM, the
lxxxl Scenario l's 2028 implementation date for in-production airplanes would be a production cut-off, which means
that in-production airplane that do not comply with the proposed standards after this date would not be allowed
enter into service or be built. Also, Scenario 1 has a 2023 implementation date for in-production airplanes with
adverse GHG emission changes or significant in-production type changes. This provision means that after 2023,
applications to change a type design of a non-GHG certificated airplane that either increase the Metric Value of
the airplane, increase the MTOM of the airplane, or significantly change the airplane's GHG emissions
(significant decrease in GHG emissions) would be required to comply with the in-production rule. The provision
is meant to capture changes to those non-GHG certificated airplanes built prior to the production cut-off date of
2028.
lxxxn por scenarj0 2, the production cut-off date would be 2023.
lxxxiii U.S., United States Position on the ICAO Aeroplane CO2 Emissions Standard, Montreal, Canada, CAEP10
Meeting, February 1-12, 2016, Presented by United States, CAEP/10-WP/59. Available in the docket for this
proposed rulemaking, Docket EPA-HQ-OAR-2018-0276.
lxxxiv In-production airplanes that are dedicated freighters have developed a unique market segment for the business
case of providing air cargo transport services. Demand for new purpose-built freighters is relatively low,
therefore they are produced in smaller volumes than their passenger equivalents. Because of the size of the
market, manufacturers of dedicated freighters may have a potentially limited business case for making
improvements to these airplanes.
ICAO/CAEP, United States Position on the ICAO Aeroplane CO2 Emissions Standard, Tenth Meeting of CAEP,
Montreal, Canada, February 1 to 12, 2016, CAEP/10-WP/59.
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Analysis of Alternatives
stringency would be similar to ICAO S09 and be 2.5 percent stricter compared to Scenario l's
SL8.5 (and Scenario 2). For new type design airplanes 60 tons or less MTOM, the stringency
would match ICAO S06 and be 2 percent stricter than Scenario 1 and Scenario 2's SL5. For in-
production airplanes greater than 60 tons MTOM, we consider a range of stringencies (or two
stringencies) as part of Scenario 3. For these in-production airplanes, the stringency would be
similar to either ICAO S08 or S09 and be 2 to 7 percent stricter (depending on the MTOM)
compared to Scenario 1 and Scenario 2's SL7. For in-production airplanes 60 tons or less
MTOM, the stringency would match ICAO S05 and be 3 to 4 percent stricter than Scenario 1
and Scenario 2's SL3.
Scenario 3 reflects the position proposed by the U.S. as an ICAO Member country. However,
with U.S. concurrence the tenth meeting of ICAO/CAEP, which occurred in February 2016, did
not adopt the U.S. Scenario 3-equivalent position.lxxxv For harmonizing with the international
standards and providing global consistency of standards, which would ensure all the world's
manufacturers need to comply (or certify) to the same standards and no U.S. manufacturer finds
itself at a competitive disadvantage, we are proposing standards that match the ICAO standards
(see further rationale for the proposed standards compared to Scenario 3 later in section 6.4).
Figure 6-3 and Figure 6-4 below show the in-production stringencies for the three scenarios as
plots.lxxxvi Figure 6-3 shows the scenarios over the entire MTOM range, and Figure 6-4 zooms in
on the scenarios below 100 tons MTOM.lxxxvu In Figure 6-3 and Figure 6-4, Scenario 1 is red,
Scenario 2 is blue, and Scenario 3 is green. The lines for Scenarios 1 and 2 are identical in
stringency level, and they only differ in their effective dates. Thus, they overlap in these figures.
Scenario 3 is shown as a range in stringency options for in-production airplanes as described
above (CAEP S08 or S09). Three metric values are plotted for each airplane, corresponding to
the values for each scenario's effective date. For the scenarios with different effective dates, the
projection of constant annual improvement in fuel efficiency metric value applied for each
airplane leads to the difference in metric value for the same airplane — as described earlier in
Chapter 2. Note the metric values for Scenarios 2 and 3 are the same since they have the same
effective dates.
The solid red circles represent the metric value each airplane would have at Scenario 1 's 2028
in-production applicability date. The open red circles represent the metric value each out of
production airplane would have at 2028 (Scenario 1). The solid blue and green circles represent
the metric value each airplane would have at Scenario 2 and Scenario 3's 2023 in-production
applicability date. The open blue and green circles represent the metric value each out of
production airplane would have at 2023 (Scenarios 2 and 3). With fewer baseline improvement
lxxxv ICAO/CAEP, United States Position on the ICAO Aeroplane CO2 Emissions Standard, Tenth Meeting of
CAEP, Montreal, Canada, February 1 to 12, 2016, CAEP/10-WP/59.
lxxxvi analySis focused on in-production airplanes because, as described in Chapter 2, a technology response is
not necessary for new type design airplanes to meet the scenarios,
lxxxv 11 scenarj0 1 (and Scenario 2) would have a constant metric value or stringency level for MTOMs between 60
tons and 70.107 tons. For the purposes of presenting Scenario 3 in Figure 6-3 and Figure 6-4, Scenario 3 also has
a constant stringency level in this MTOM range. ICF analyzed Scenario 3 with a varying stringency level in this
same MTOM range or a kink point at 60 tons MTOM (similar to the ICAO/CAEP SOs), which is consistent with
the U.S. position proposed by the U.S. ICAO Member at the tenth meeting of ICAO/CAEP. The results of
airplanes affected by Scenario 3 do not change with either having a constant stringency level between 60 tons and
70.107 tons or instead having a kink point at 60 tons MTOM.
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Analysis of Alternatives
years prior to applicability, the 2023 metric values (blue and green circles) would be expected to
be higher than the corresponding 2028 values (red circles).
3.0
Sen. 1
Sen. 2
Sen. 3
Sen. 1 In-Prod. MV
Sen. 1 Out of Prod. MV
Sen. 2,3 In-Prod. MV
Sen. 2,3 Out of Prod. MV
200	300	400
MTOM (1000 kg)
600
Figure 6-3 - In-Production Airplane Stringency Lines for the Three
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Analysis of Alternatives
1.0
0.8
>
0.6
/• QO
sfr
0.4
Sen. 1
Sen. 2
Sen. 3
Sen. 1 In-Prod. MV
Sen. 1 Out of Prod. MV
Sen. 2,3 In-Prod. MV
Sen. 2,3 Out of Prod. MV
4—>
QJ
5!
0.2
0.0
0
20
40
60
80
100
MTOM (1000 kg)
Figure 6-4 - Detail of In-Production Airplane Stringency Lines for Airplane Below 100 tons MTOM
6.2 GHG Emission Redactions and Costs of Two Alternative Scenarios
The methods used to analyze the GHG costs and emission reductions from the proposed
standards and the two alternative scenarios are described in Chapter 2, Chapter 4, and Chapter 5.
Although the proposed standards (Scenario 1) do not have any costs or emission reductions,
except for limited reporting costs (based on the rationale provided in the earlier chapters), the
effects of the proposed standards were analyzed using the same methods as the two alternative
scenarios.
6.2.1 Scenario 2
Scenario 2 would not be expected to result in additional GHG reductions or costs relative to
the proposed standards or Scenario 1. As described earlier in Chapter 2 and Chapter 5 for the
proposed standards (Scenario 1), under Scenario 2 manufacturers comply through already
developed or developing technologies to respond to ICAO standards. Moreover, as described in
Chapter 2, with the baseline constant annual improvement in fuel efficiency metric value in the
absence of rules, all but one airplane model are still expected to be in production and compliant
with the 5-year pull ahead associated with Scenario 2. The exception is a single dedicated
freighter airplane (Boeing 767-3ERF); however, the 5-year accelerated implementation date
would not apply to dedicated freighters for Scenario 2. This provision would mean that the 767-
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Analysis of Alternatives
3ERF is not disadvantaged by Scenario 2, and those additional years allow for it to come into
compliance given the assumed baseline constant annual improvement in fuel efficiency metric
value.62
However, it is informative to describe the 767-3ERF's metric value compared with Scenario
2's stringency level but without a five-year delay for dedicated freighters (for a 2023 effective
date). The 767-3ERF's metric value would be 7.91 percent greater than Scenario 2 in 2023 (does
not meet level of Scenario 2). With a 1 percent design margin,lxxxvm as described earlier in
Chapter 2, there would need to be an 8.91 percent improvement in the 767-3ERF metric value by
2023 to comply with Scenario 2 (and an 8.91 percent reduction in GHG emissions per 767-
3ERF). With this amount of improvement needed for the 767-3ERF to comply with Scenario 2
in 2023 and the 767-3ERF expected to be end production in 2023, the manufacturer would be
anticipated to pull forward its final year of production by one year (2022) instead of making the
investment for the technology response to comply with Scenario 3. Yet, with the dedicated
freighter delay to 2028 in Scenario 2, this pull forward in the end of production for the 767-3ERF
would not need to occur. As described above, the 767-3ERF would comply with Scenario 2
based on its expected end of production in 2023 in the absence of a standard, and thus, there
would be no emission reductions or costs from Scenario 2 based on the 767-3ERF. In addition,
even if we were to change the above expectations, the manufacturer of the 767-3ERF could
utilize the proposed exemption provisions described in section V.E of the preamble, which are
intended for airplanes at the end of their production life. If Boeing chose to apply for an
exemption and it was granted, the 767-3ERF would not need to respond to Scenario 2, and thus,
there would be no resultant emission reductions or costs for Scenario 2 from the 767-3ERF.
6.2.2 Scenario 3
Scenario 3 both accelerates the implementation date by 5 years and increases the stringency.
This would be expected to result in additional GHG reductions and costs relative Scenarios 1 and
2. Using the same assumptions applied to the other scenarios, the baseline constant annual
improvement in fuel efficiency metric value for each airplane and the delay to 2028 for dedicated
freighters, there are limited reductions and costs from Scenario 3. These limited costs and
emission reductions are due the impacts on a single airplane model, the Airbus A380.
As described earlier in a Chapter 5 footnote, on February 14, 2019, Airbus made an
announcement to end A380 production by 2021 after Emirates airlines reduced its A380 order by
39 airplanes and replaced them with A330s and A350s.lxxxix The early exit of A380 would result
in no costs and no emission reductions from Scenario 3. However, this EPA analysis of Scenario
3 was conducted prior to Airbus's announcement, so the analysis did not consider the effect of
the A380 ending production in 2021. Thus, this analysis results in limited costs and emission
reductions for Scenario 3.
lxxxvm 2018 ICF updated analysis indicated that for those airplanes that do not meet a stringency level, an
additional 1 percent design margin above the shortfall would need to be reached. This design margin would
ensure the technology addresses the response to the stringency level (actual CO2 reduction for a given technology
is variable).
ixxxk Tjjg Airbus press release is available at: https://www.airbus.coni/newsrooni/press-re1eases/en/2019/02/airbus-
and-emirates-reach-agreement-on-a380-fleet	sign-new-widebody-orders.html. last accessed on February 10,
2020.
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Analysis of Alternatives
6.2.2.1	767-3ERF
Due to the dedicated freighter 5-year delay in Scenario 3, the 767-3ERF would comply with
Scenario 3 for the same reason described above for Scenario 2. However, it is informative to
describe the 767-3ERF's metric value compared to the stringency level of Scenario 3. The 767-
3ERF's metric value would be 15.7 percent greater than Scenario 3. With a 1 percent design
margin, there would need to be a 16.7 percent improvement in the 767-3ERF metric value by
2023 to comply with Scenario 3 (and a 16.7 percent reduction in GHG emissions per 767-3ERF).
As with Scenario 2, with this greater amount of improvement (for Scenario 3 compared to
Scenario 2) needed for the 767-3ERF to comply with Scenario 3 in 2023 and the 767-3ERF
expected to end production in 2023, the manufacturer would be even more likely (versus
Scenario 2) to pull forward its final year of production by one year (2022) instead of making the
investment to comply with Scenario 3. Yet, with the dedicated freighter delay to 2028 in
Scenario 3, this pull forward in the end of production for the 767-3ERF would not be needed. As
described above, the 767-3ERF would comply with Scenario 3 based on its expected end of
production in 2023 in the absence of a standard, and thus, there would be no emission reductions
or costs from Scenario 3 based on the 767-3ERF. In addition, (as with Scenario 2) even if we
were to change the above expectations, the 767-3ERF could utilize the proposed exemption
provisions described in section V.E of the preamble, which are intended for airplanes at the end
of their production life.
6.2.2.2	A380
For Scenario 3, with the baseline constant annual improvement, the 5-year earlier effective
date (except dedicated freighters that retain the 2028 effective date), and tighter stringency levels
for in-production airplanes, one in-production airplane model would not comply. Further, the
impacted airplane model would need a technology response to stay in production after the effect
date, and the technology response would lead to GHG reductions and costs (and fuel savings)
compared to Scenarios 1 and 2. This airplane model is the Airbus A380-842/A380-861 (herein
referred to as the "A380"). The A380 does not comply with the in-production level that is 7
percent more stringent than Scenarios 1 and 2 (Scenario 3 would be similar to the level of ICAO
S09 for in-production airplanes greater than 60 tons MTOM and would be effective in 2023).
The A380's metric value would be 3.24 percent greater than Scenario 3. With a 1 percent design
margin, there would need to be a 4.24 percent improvement in the A380 metric value by 2023 to
comply with the Scenario 3 metric value requirement. Applying a constant annual improvement
in fuel efficiency metric value would mean 1.71 percent of these reductions would already have
been obtained by 2023 (by business as usual technology improvements in the absence of a
standard), and the remaining portion of the reductions, 1.53 percent, would be achieved through
technology response. With the 1 percent design margin, the technology response would become
2.53 percent. Table 6-5 shows the result of this method for determining the metric value
reduction for technology response for the A380.
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Analysis of Alternatives
Table 6-5 - A380 Scenario 3 - Implementation of Technology Response

No Design Margin
1% Design Margin
Percent MV Greater than Scenario 3
3.24%
4.24%
Residual Implemented MV Improvement
(1.71%)
(1.71%)
Technology Response Improvement Target
1.53%
2.53%
Technology Response: Adaptive Trailing Edge
2.00% of A380 baseline MV
2.00% of A380 baseline MV
Technology Response: ECS Aero
N/A
0.63% of A380 baseline MV
Non-Recurring Cost to Implement Technology
Response
$493M
$580M
Based on the supply curve method in the 2018 ICF updated analysis, which is described
earlier in Chapter 2, the anticipated technology response (or the most economical technology
response) for the A380 would be the adaptive trailing edge and environmental control system
(ECS) aerodynamic cleanup and on-demand ECS scheduling, if the 1 percent design margin is
necessary (and only adaptive trailing edge if the 1 percent design margin is not needed). These
technology responses are described further in Chapter 2. Figure 6-5 provides the supply curve
for the technology response of the A380.4,xc
xc As described in Chapter 2 and earlier in section 6.2.2.2, for a given future year, a manufacturer's technology
insertion is assumed to have progressed up the supply curve (i.e. technologies with largest improvement and most
economical cost are implemented first). Therefore, these economical technologies would have already been
implemented by the stringency year, and they will not be available for future investment. Then, we overlay the
smoothed forecasted incremental metric value improvement by the stringency year on the airplane model's
discrete supply-curve. From this overlay, ICF identified the most economical technologies that would already
have been implemented by the stringency year, and these technologies represent business as usual improvement
or continuous metric value improvement by the stringency year - or 2023 improvement level. The red-dashed
line in Figure 6-2 shows the continuous metric value improvement by 2023 or the 2023 improvement level.
Subsequently, the remaining technologies not yet implemented, which are those technologies that are to the right
of the red-dashed line, would be available for the technology response needed to meet Scenario 3.
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$6,000
$5,000
J $4/) 00
$3/) 00
m $2,000
$1,000
Analysis of Alternatives
A380 Incremental Improvement Technology Supply Curve
Gap to scenario (%}
AUO-M1
2023 Improvement Level
Aerodynamic AJ®U Fairing/Aft
body rede sign
Other Aerodynamic Improvements
Other Sy«em s Improvements
Hybrid Liminv Sow Control •
Empennage
P»fclet Coatings
Adaptive Trailtng Edge
Variable Camber Trailing Edge -
Morphirg
ECS Aero and On Demand ECS
Scheduling
SHI fteduong Profile ot the light*
i i Engine Technologies
Advanced Wing bp Devices -
Retrofit
—A— MV Supply Curve tine
10% 12% 14%
Metric Value Improvement
Figure 6-5 - A380 Incremental Improvement Technology Supply Curve
6.2.2.2.1	A380s GHG Emission Reductions
For Scenario 3, we also estimated that the U.S. covered airplane GHG emissions would be
reduced in 2030 and 2040 from the anticipated technology response for the A380s built after
January 1, 2023 (Scenario 3's effective date for in-production airplanes over 60 tons MTOM).
(Note, as described in section III of the preamble, CO2 represents 99 percent of all GHGs emitted
from both total U.S. airplanes and U.S. covered airplanes (in megatonnes of CO2 equivalent),
and nitrous oxide (N2O) represents 1 percent of GHGs emitted from total airplanes and U.S.
covered airplanes.) However, the emissions reductions from such a response would be limited
since the 2018 ICF updated analysis projects that the number of A380s that would be built after
January 1, 2023, would be about 40 airplanes. The cumulative reductions in U.S. covered
airplane GHG emissions for Scenario 3XC1 would be as follows (percentage and absolute
reductions): about 0.7 percent and 0.6 Mt CO2 equivalent for 2030 and about 0.8 percent and 1.4
Mt CO2 equivalent for 2040. Further details about the emissions impacts of Scenario 3 are
provided in Chapter 5.
6.2.2.2.2	A380 s Costs
Based on the same reasons as discussed earlier in this section there would be limited
technology response costs from only the A380 needing to respond to Scenario 3. As described
earlier, the technology response for the A380 to comply would be the adaptive trailing edge and
ICF projected that about 40 A38Qs would be built globally after January 1, 2023. The cumulative reductions in
U.S. covered airplane GHG emissions would be from about 40 A380s receiving a technology response for
Scenario 3 from 2023 to 2030. However, as discussed earlier in Chapter 5, we did not connect these cumulative
GHG reductions to a specific number of A380s used in the EPA analysis, but instead we connected the reductions
to a specific amount of operations.
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ECS aerodynamic cleanup and on-demand ECS scheduling. We estimated that the non-recurring
cost to apply this technology response to the A380 would be about $415 million and $501
million (in 2015$), at 7 and 3 percent discount rates respectively.™11 Chapter 2 provides the
details of the cost methodology.
Similar to the earlier discussion in Chapter 2, the 2018 ICF updated analysis indicates that if
technologies would add significant recurring costs (recurring operating and maintenance costs)
to an airplane and/or an operator (e.g., an air carrier), an air carrier would likely not add these
technologies to their airplanes. Thus, the 2018 ICF updated analysis estimates that there would
be no recurring costs for the projected technology response of the A380 to Scenario 3.
In addition, for Scenario 3, the A380 could apply to utilize the proposed exemption provisions
(described in section V.E of the preamble), which are intended for airplanes at the end of their
production life. If Airbus chose to apply for an exemption and it was granted, the A380 would
not need to respond to Scenario 3, and thus, there would be no resultant emission reductions or
costs for Scenario 3.
6.2.2.3 Monetized Benefits for A 380
We estimate the climate benefits associated with alternative regulatory Scenario 3 using a
measure of the domestic social cost of carbon and nitrous oxide (SC-CO2 and SC-N2O).
Scenario 3 is the only alternative scenario with potential SC-CO2 and SC-N2O emission
reductions. The social cost of these greenhouse gases is a metric that estimates the monetary
value of impacts associated with marginal changes in CO2 emissions in a given year. It includes
a wide range of anticipated climate impacts, such as net changes in agricultural productivity and
human health, property damage from increased flood risk, and changes in energy system costs,
such as reduced costs for heating and increased costs for air conditioning. It is typically used to
assess the avoided damages as a result of regulatory actions (i.e., benefits of rulemakings that
lead to an incremental reduction in cumulative global CO2 emissions). The SC-CO2 and SC-N2O
estimates used in this Draft TSD focus on the direct impacts of climate change that are
anticipated to occur within U.S. borders.
The SC-CO2 and SC-N2O estimates used in this Draft TSD are interim values developed
under E.O. 13783 — for use in regulatory analyses until an improved estimate of the impacts of
climate change to the U.S. can be developed based on the best available science and
economics.™111 See the Appendix63 for additional discussion of E.O. 13783 and an explanation of
the modeling steps involved in estimating the domestic estimates used in this Draft TSD.
xcn We began by using the ICF's estimate for undiscounted non-recurring costs of $580 million for this technology
response (of these two technologies together). Subsequently, we allocated a fifth of these NRC costs to each of
the five years preceding 2023 since the costs would typically be spent over a five-year period (instead of all in
one year). Next, we discounted these annual costs back to 2015 at 7 percent and 3 percent discount rates to
calculate the resulting total present value of non-recurring costs of $415 million and $501 million (in 2015$),
respectively.
xcm Such improved domestic estimates would take into considerations the recent recommendations from the National
Academies of Sciences, Engineering, and Medicine for a comprehensive update to the current methodology to
ensure that the social cost of greenhouse estimates reflect the best available science. While the Academies'
review focused on the methodology to estimate the social cost of carbon (SC-CO2), the recommendations on how
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Analysis of Alternatives
Table 6-6 and Table 6-7 present the average domestic SC-CO2 and SC-N2O estimates,
respectively, across all the model runs using both 3 and 7 percent discount rates for the years
2015 to 2050. As with the global social cost of greenhouse gas estimates, the domestic estimates
increase over time because future emissions are expected to produce larger incremental damages
as physical and economic systems become more stressed in response to greater climatic change,
and because gross domestic product (GDP) is growing over time and many damage categories
are modeled as proportional to gross GDP.
Table 6-6 - Interim Domestic Social Cost of CO2, 2015-2050 (in 2015$ per metric ton)*
Year
Discount Rate and Statistic
3% Average
7% Average
2015
$6
$1
2020
6
1
2025
7
1
2030
8
1
2035
8
2
2040
9
2
2045
10
2
2050
10
2
* These SC-CO2 values are stated in $/metric ton CO2 and rounded to the nearest dollar. The estimates
vary depending on the year of CO2 emissions and are defined in real terms, i.e., adjusted for inflation
using the GDP implicit price deflator.
Table 6-7 - Interim Domestic Social Cost of N2O, 2015-2050 (in 2015$ per metric ton)*
Year
Discount Rate and Statistic
3% Average
7% Average
2015
$1900
$310
2020
2100
360
2025
2300
440
2030
2600
510
2035
2800
600
2040
3100
700
2045
3400
810
2050
3700
920
* These SC-N2O values are stated in $/metric ton N2O and rounded to two significant digits. The
estimates vary depending on the year of N2O emissions and are defined in real terms, i.e., adjusted for
inflation using the GDP implicit price deflator
to update many of the underlying modeling assumptions also pertain to the SC-N2O estimates since the
framework used to estimate SC-N2O is the same as that used for SC-CO2. See National Academies of Sciences,
Engineering, and Medicine, Valuing Climate Damages: Updating Estimation of the Social Cost of Carbon
Dioxide, Washington, D.C., January 2017. http://www.nap.edu/catalog/24651/valuing-climate-changes-updating-
estimation-of-the-social-cost-of.
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Analysis of Alternatives
The estimates in Table 6-6 and Table 6-7 are used to monetize the domestic climate benefits.
Forecasted changes in CO2 and N2O emissions in a given year, expected as a result of Scenario
3, are multiplied by the SC-CO2 and SC-N2O estimates, respectively, for that year.
Table 6-8 provides annual estimates of SC-CO2 benefits associated with Scenario 3, as well as
the total present value of SC-CO2 benefits. Table 6-9 provides annual estimates of the SC-N2O
benefits, as well as the total present value of SC-N2O benefits. As described earlier, N2O
represents 1 percent of GHGs emitted from U.S. covered airplanes, and therefore contributes a
small portion of climate benefits compared to C02.XC1V Table 6-10 provides annual estimates of
fuel savings, as well as the total present value of fuel savings.
Fuel savings, domestic climate benefits, and total benefits associated with Scenario 3 are
presented in Table 6-11 and Table 6-12.xcv
XC1V Global warming potential (GWP) is a quantified measure of the globally averaged relative radiative forcing
impacts of a particular greenhouse gas. It is the accumulated radiative forcing within a specific time horizon,
relative to that of the reference gas CO2. GWP-weighted emissions are measured in megatonnes of CO2
equivalent (Mt C02 Eq.), and GWPs are based upon a 100-year time horizon.
U.S. EPA, 2020: Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2018, 733 pp., U.S. EPA Office
of Air and Radiation, EPA 430-R-20-002, April 2020. Available at:
hl:l:ps://www.epa.gov/ahgeniLssitms/inventory-us-greenhouse-gas-emissions-and-sinks-1990-2018 (last accessed
June 18, 2020).
xcv The airplane GHG emission reductions in the U.S. described earlier in this section for Scenario 3 directly relate to
airplane fuel savings in the U.S. For Scenario 3, the EPA approximated the value of airplane fuel burn savings
from the reduced demand attributable to improved airplane fuel efficiency, due to the technology response
described earlier. To estimate these airplane fuel savings for Scenario 3, we used the average jet fuel price per
year (2023 through 2040) from the Annual Energy Outlook 2018. The jet fuel prices were in 2017$, and we
converted these jet fuel prices to 2015$.
U.S. Energy Information Administration (EIA), 2018: Annual Energy Outlook 2018, #AEO2018, Table 12 -
Petroleum and Other Liquids Prices, Available at www.eia.gov/aeo (last accessed April 11, 2018).
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Analysis of Alternatives
Table 6-8 - Detailed Domestic CCh-Related Benefits for Scenario 3x( vi'x(vii'x( viii (Millions of 2015$)
Year
Domestic
Domestic Climate
Domestic Climate

Reductions
Benefits
Benefits

C02
SC-COz
SC-COz


(3%)
(7%)
2023*™
0.03
$0.19
$0.03
2024
0.06
0.38
0.06
2025
0.08
0.59
0.10
2026
0.08
0.60
0.10
2027
0.08
0.61
0.10
2028
0.08
0.62
0.10
2029
0.08
0.63
0.11
2030
0.08
0.63
0.11
2031
0.08
0.64
0.11
2032
0.08
0.65
0.12
2033
0.08
0.66
0.12
2034
0.08
0.66
0.12
2035
0.08
0.67
0.13
2036
0.08
0.67
0.13
2037
0.08
0.67
0.13
2038
0.07
0.67
0.13
2039
0.07
0.67
0.13
2040

0.67
0.13
Total Present Value (3%)

$6.60
-
Total Present Value (7%)

--
$0.63
xcvl Estimates are rounded to two significant figures.
xcvii The SC-CO2 and SC-N2O estimates used in this Draft TSD are interim values developed under E.O. 13783 and
are based on assumed 3 and 7 percent discount rates used in their estimation. Consistent with OMB Circular A-4
guidance, the present value of the stream of annual climate and fuel savings benefits also use a 3 and 7 percent
discount rate.
xcviii Global SC-CO2 results are provided in the appendix of this Draft TSD.
XC1X Since Scenario 3's implementation date for most in-production airplanes would be 2023, this is the first year that
benefits would begin to occur.
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Analysis of Alternatives
Table 6-9 - Detailed Domestic N20-Related Benefits for Scenario 3C (Millions of 2015$)
Year
Domestic Climate
Domestic Climate

Benefits
Benefits

SC-NzO
SC-NzO

(3%)
(7%)
2023
$0,002
$0.0003
2024
0.004
0.001
2025
0.01
0.001
2026
0.01
0.001
2027
0.01
0.001
2028
0.01
0.001
2029
0.01
0.001
2030
0.01
0.001
2031
0.01
0.001
2032
0.01
0.001
2033
0.01
0.001
2034
0.01
0.001
2035
0.01
0.002
2036
0.01
0.002
2037
0.01
0.002
2038
0.01
0.002
2039
0.01
0.002
2040
0.01
0.002
Total Present Value (3%)
T—1
0
-
Total Present Value (7%)
--
$0.01
c Global SC-N2O results are provided in the appendix of this Draft TSD.
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Analysis of Alternatives
Table 6-10 - Detailed Domestic Fuel Savings for Scenario 3 (Millions of 2015$)
Year
Fuel Savings
2023
$6.8
2024
14
2025
21
2026
21
2027
22
2028
22
2029
22
2030
23
2031
23
2032
23
2033
23
2034
23
2035
23
2036
23
2037
23
2038
23
2039
23
2040
23
Total Present Value (3%)
$230
Total Present Value (7%)
$130
Table 6-11 - Summary of Domestic Climate-Related Benefits and Fuel Savings for Scenario 3d
(3% Discount Rate, Millions of 2015$)
Year
Domestic Climate Benefits
(3%)
Fuel Savings
Total Benefits
Domestic Climate Benefits @ 3%
2023
$0.2
$6.8
$7
2025
0.6
21
22
2030
0.6
23
23
2035
0.7
23
24
2040
0.7
23
24
Total Present Value (3%)
$6.7
$230
$240
C1 Domestic climate benefits in this table includes SC-CO2 and SC-N2O benefits.
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Analysis of Alternatives
Table 6-12 - Summary of Domestic Climate-Related Benefits and Fuel Savings for Scenario 3cii
(7% Discount Rate, Millions of 2015$)
Year
Domestic Climate Benefits
(7%)
Fuel Savings
Total Benefits
Domestic Climate Benefits @ 7%
2023
$0.03
$6.8
$6.9
2025
0.1
21
21
2030
0.1
23
23
2035
0.1
23
24
2040
0.1
23
23
Total Present Value (7%)
$0.6
$130
$130
The limitations and uncertainties associated with the global social cost of greenhouse gas
estimates, which were discussed at length in recent rules, likewise apply to the domestic social
cost of greenhouse gas estimates presented in this Draft TSD.cm Some uncertainties are captured
within the analysis, as discussed in detail in the Appendix, while other areas of uncertainty have
not yet been quantified in a way that can be modeled. For example, limitations include the
incomplete way in which the integrated assessment models capture catastrophic and non-
catastrophic impacts, their incomplete treatment of adaptation and technological change, the
incomplete way in which inter-regional and inter-sectoral linkages are modeled, uncertainty in
the extrapolation of damages to high temperatures, and inadequate representation of the
relationship between the discount rate and uncertainty in economic growth over long time
horizons. The science incorporated into these models understandably lags behind the most
recent research, and the limited amount of research linking climate impacts to economic damages
makes the modeling exercise even more difficult.
These individual limitations and uncertainties do not all work in the same direction in terms of
their influence on the estimates. In accordance with guidance in OMB Circular A-4 on the
treatment of uncertainty, the Appendix provides a detailed discussion of the ways in which the
modeling underlying the development of the social cost of greenhouse gas estimates used in this
Draft TSD addressed quantified sources of uncertainty, and presents a sensitivity analysis to
show consideration of the uncertainty surrounding discount rates over long time horizons.
In addition to requiring reporting of impacts at a domestic level, OMB Circular A-4 states that
when an agency " evaluate [s] a regulation that is likely to have effects beyond the borders of the
United States, these effects should be reported separately" (page 15). This guidance is relevant
to the valuation of damages from CO2 and other GHGs, given that GHGs contribute to damages
around the world independent of the country in which they are emitted. Therefore, in accordance
with this guidance in OMB Circular A-4, the Appendix presents the global climate benefits from
this proposed rulemaking using global SC-CO2, SC-CH4, and SC-N2O estimates based on both 3
and 7 percent discount rates. Note EPA did not quantitatively project the full impact of the
proposed action on international trade and the ultimate distribution of compliance costs, so it is
not possible to present estimates of global costs resulting from the proposed action.
cu Domestic climate benefits in this table includes SC-CO2 and SC-N2O benefits.
ciii See e.g., the EPA's 2019 Affordable Clean Energy (ACE) rulemaking (84 FR 32520, July 8, 2019).
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6.3 Sensitivity Case Studies
As described earlier in Chapter 5, for the three scenarios, we conducted sensitivity studies on
the emissions reductions effect of 1) not having continuous annual improvement (continuous
improvement was assumed in our main analysis) and 2) having extended production of the A380
and 767-3ERF to 2030 (instead of using the main analysis' assumption of 2025 and 2023,
respectively). These sensitivity study criteria are nearer to the assumptions in the ICAO/CAEP
analysis.
6.3.1	Emission Reductions for Scenario 3
Under the combined sensitivity studies for Scenario 3, the A380 would not comply with the
scenario by its effective dates and therefore would need a technology response of about 4 percent
in improvements to the metric value (with the 1% design margin). The 767-3ERF (dedicated
freighter) would not meet Scenario 3 with or without continuous annual improvement, and its
technology response status would be mostly driven by the end of production assumption (thus
needing a technology response of about 17 percent in improvements to the metric value in 2028).
The total U.S. CO2 cumulative reductions from the combination of these two sensitivity case
studies would be as follows: about 4.2 Mt CO2 equivalent for 2030 and about 15 Mt CO2
equivalent for 2040. As indicated in Chapter 5, these results show that 7 to 11 times greater (or
600 percent to 1000 percent greater) emission reductions for Scenario 3 would occur with the
assumptions in the combined sensitivity studies compared to the main analysis (4.2 Mt CO2
equivalent versus 0.6 Mt CO2 equivalent in 2030 and 15 Mt CO2 equivalent versus 1.4 Mt CO2
equivalent in 2040, respectively).
Separate from these combined sensitivity studies, we also analyzed the emission reductions
using ICAO/CAEP's assumptions of airplane fleet evolution and airplane operations (used
PIANO for airplane CO2 emission rates). Using these same assumptions as ICAO, the total U.S.
CO2 cumulative reductions would be about 110 Mt CO2 equivalent for Scenario 3.
6.3.2	Emission Reductions for Scenarios 1 and 2
For the combined sensitivity studies of Scenarios 1 and 2, the A380 would not comply with
either scenario by their effective dates and therefore would need a technology response of about
2 percent in improvements to the metric value (with the 1% design margin). The 767-3ERF
(dedicated freighter) would not meet Scenarios 1 and 2 with or without continuous annual
improvement, and its technology response status would be mostly driven by the end of
production assumption. For the results of this combined sensitivity study, the total U.S. CO2
cumulative reductions in 2040 would be about 3 Mt CO2 equivalent for Scenario 1 and about 4
Mt CO2 equivalent for Scenario 2.
In the sensitivity case of no continuous annual improvement but no extended production,
Scenario 1 would result in no emission reductions because the A380 would be out of production
by 2025. However, in this case, Scenario 2 would result in limited emission reductions from the
technology response improvement of 2 percent for the A380 due to the 5-year accelerated
implementation date (2023). The total U.S. CO2 cumulative reductions in 2040 would be about 1
Mt CO2 equivalent in the U.S.
In the sensitivity case of extended production but with continuous improvement, the emission
reductions would result from only the 767-3ERF since the A380 would meet the scenarios.
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Analysis of Alternatives
Since the 5-year accelerated implementation date is not proposed for freighters, Scenarios 1 and
2 would have the same emission reductions effect, and the estimated the total U.S. CO2
cumulative reductions in 2040 would be about 1 Mt CO2 equivalent in the U.S.
Separate from these sensitivity studies and using the same assumptions as ICAO/CAEP,clv the
total U.S. CO2 cumulative reductions would be about 50 Mt CO2 equivalent for Scenario 1 and
about 75 Mt CO2 equivalent for Scenario 2.
However, as discussed in Chapter 5 for all three scenarios, we believe that the EPA main
analysis assumptions of business as usual improvements in the absence of standards (continuous
annual improvement) and the independently developed and peer reviewed technology responses
(including expected end of production expectations) are based on more up to date inputs and
assumptions, in comparison to these sensitivity studies.
6.3.3 Costs for All Three Scenarios
We did not conduct specific sensitivity case studies for costs based on the above criteria for
the three scenarios, but a rough approximation of such sensitivity case studies is a comparison of
our non-recurring costs (NRC) to ICAO/CAEP analysis' NRC (see Chapter 2 of this Draft TSD,
particularly refer to Table 2-12 and
Table 2-13 for a comparison of NRC for a range of percent metric value improvements). We
can draw insight from this rough approximation even though the criteria in our sensitivity case
studies do not exactly match the assumptions in the ICAO/CAEP analysis. Similar to our
sensitivity studies for emissions reductions, the methodology for the ICAO/CAEP's NRC
analysis assumed no continuous annual improvement and included extended production of the
A380 and 767-3ERF (as well as numerous other airplanes). Thus, it is informative to compare
our NRC results to ICAO/CAEP results since they may serve as a general sensitivity analysis of
our costs. As with emission reductions from our sensitivity studies, the NRC results from
ICAO/CAEP are typically much greater than our NRC results (on average about 170 percent
greater for representative airplanes in the various airplane categories). Also, section 2.6 of this
Draft TSD describes fuel savings based on our analysis and the ICAO/CAEP analysis, and
ICAO/CAEP's results are much greater. The magnitude of these differences is expected.
ICAO/CAEP's technology responses were based on technology frozen in 2016-2017 compared
to the EPA's responses that considered technologies available in 2017, but with continuous
improvement of metric values for in-production and in-development (or on-order) airplanes from
2010 to 2040 based on the incorporation of these technologies onto these airplanes (over this
same timeframe). Also, as discussed in Chapter 2, ICAO/CAEP's top-down approach likely
included all airplane development costs (type certification, noise, in-flight entertainment, etc.)
instead of only those costs for CO2 improvements. Thus, we believe the assumptions in our cost
analysis are based on more up to date inputs and assumptions.
In addition, for the extended production criteria (for the scenarios), manufacturers could apply
to use the proposed exemption provisions (described in section V.E of the preamble), which are
intended for airplanes at the end of their production life. If manufacturers chose to apply for an
Clv We analyzed the emission reductions using ICAO/CAEP's assumptions of airplane fleet evolution and airplane
operations (used PIANO for airplane CO2 emission rates).
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Analysis of Alternatives
exemption and it was granted, the A380 and 767-3ERF would not need to respond, and thus,
there would be no resultant emission reductions or costs.
6.4 Summary
As described earlier in this Draft TSD, for harmonizing with the international standards and
providing global consistency, which would ensure all the world's manufacturers comply (or
certify) to the same standards and no U.S. manufacturer finds itself at a competitive
disadvantage, the EPA is proposing standards (Scenario 1) that match the international standards.
As discussed earlier, according to the EPA analysis, Scenario 2 (accelerated implementation
dates) has no costs and benefits, which is the same impact as Scenario 1. Scenario 3 (both
accelerated implementation dates and stricter stringency levels) has limited costs, which
outweigh the limited benefits. As shown in Table 6-13, for Scenario 3, the present value of non-
recurring costs would be about $415 million and $501 million (in 2015$), at 7 and 3 percent
discount rates respectively. The present value of total benefits would be about $130 million and
$240 million (in 2015$), at 7 and 3 percent discount rates respectively. Estimated net benefits
(benefits minus costs) therefore range from -$285 million to -$261 million, at 7 and 3 percent
discount rates respectively.
Table 6-13 - Present Value of Total Benefits, Total Costs, and Net Benefits for Scenario 3
(Millions of 2015$)
Present Value
3% Discount Rate
7% Discount Rate
Benefits
240
130
Costs
501
415
Net Benefits (benefits minus costs)
-261
-285
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Appendix A
A.l Overview of Methodology Used to Develop Interim Domestic SC-CO2 and SC-N2O
Estimates
E.O. 13783 directed agencies to ensure that estimates of the social cost of greenhouse gases
used in regulatory analyses "are based on the best available science and economics" and are
consistent with the guidance contained in OMB Circular A-4, "including with respect to the
consideration of domestic versus international impacts and the consideration of appropriate
discount rates" (E.O. 13783, Section 5(c)). In addition, E.O. 13783 withdrew the technical
support documents (TSDs) describing the global social cost of greenhouse gas estimates
developed under the prior Administration as no longer representative of government policy. The
withdrawn TSDs were developed by an interagency working group (IWG) that included the
DOT, EPA and other executive branch entities.
Regarding the two analytical considerations highlighted in E.O. 13783 - how best to consider
domestic versus international impacts and appropriate discount rates - current guidance in OMB
Circular A-4 is as follows. Circular A-4 states that analysis of economically significant proposed
and final regulations "should focus on benefits and costs that accrue to citizens and residents of
the United States." We follow this guidance by adopting a domestic perspective in our central
analysis. Regarding discount rates, Circular A-4 states that regulatory analyses "should provide
estimates of net benefits using both 3 percent and 7 percent." The 7 percent rate is intended to
represent the average before-tax rate of return to private capital in the U.S. economy. The 3
percent rate is intended to reflect the rate at which society discounts future consumption, which
is particularly relevant if a regulation is expected to affect private consumption directly. EPA
follows this guidance by presenting estimates based on both 3 and 7 percent discount rates in the
main analysis.
The domestic social cost of greenhouse gas estimates presented in this Draft TSD rely on the
same ensemble of three integrated assessment models (IAMs) that were used to develop the IWG
global SC-CO2 and SC-N2O estimates: DICE 2010, FUND 3.8, and PAGE 2009.cv The three
IAMs translate emissions into changes in atmospheric greenhouse concentrations, atmospheric
concentrations into changes in temperature, and changes in temperature into economic damages.
The emissions projections used in the models are based on specified socio-economic (GDP and
population) pathways. These emissions are translated into atmospheric concentrations, and
concentrations are translated into warming based on each model's simplified representation of
the climate and a key parameter, equilibrium climate sensitivity. The effect of these Earth
system changes is then translated into consumption-equivalent economic damages. As in the
IWG exercise, these key inputs were harmonized across the three models: a probability
distribution for equilibrium climate sensitivity; five scenarios for economic, population, and
emissions growth; and discount rates.CV1 All other model features were left unchanged. Future
cv The full model names are as follows: Dynamic Integrated Climate and Economy (DICE); Climate Framework for
Uncertainty, Negotiation, and Distribution (FUND); and Policy Analysis of the Greenhouse Gas Effect (PAGE).
CV1 In order to develop SC-CH4 and SC-N2O estimates consistent with the methodology underlying the SC-CO2
estimates also required augmenting the climate model of two of the IAMs to explicitly consider the path of
additional radiative forcing from a CH4 or N2O perturbation, and adding more specificity to the assumptions
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damages are discounted using constant discount rates of both 3 and 7 percent, as recommended
by OMB Circular A-4.
The domestic share of the global SC-CO2 and SC-N2O—i.e., an approximation of the climate
change impacts that occur within U.S. borderscvu—is calculated directly in both FUND and
PAGE. However, DICE 2010 generates only global estimates. Therefore, the U.S. damages are
approximated as 10 percent of the global values from the DICE model runs, based on the results
from a regionalized version of the model (RICE 2010) reported in Table 2 of Nordhaus (2017).
Although the regional shares reported in Nordhaus (2017) are specific to SC-CO2, they still
provide a reasonable interim approach for approximating the U.S. share of marginal damages
from emissions of other greenhouse gases.
The steps involved in estimating the social cost of each gas are described below. The three
integrated assessment models (FUND, DICE, and PAGE) are run using the harmonized
equilibrium climate sensitivity distribution, five socioeconomic and emissions scenarios, and two
constant discount rates described above. Because the climate sensitivity parameter is modeled
probabilistically, and because PAGE and FUND incorporate uncertainty in other model
parameters, the final output from each model run is a distribution over the SC-CO2 or SC-N2O in
year t based on a Monte Carlo simulation of 10,000 runs. For each of the IAMs, the basic
computational steps for calculating the social cost estimate in a particular year t are the
following: 1.) calculate the temperature effects and (consumption-equivalent) damages in each
year resulting from the baseline path of emissions; 2.) adjust the model to reflect an additional
unit of emissions in year t; 3.) recalculate the temperature effects and damages expected in all
years beyond t resulting from this adjusted path of emissions, as in step 1; and 4.) subtract the
damages computed in step 1 from those in step 3 in each model period and discount the resulting
path of marginal damages back to the year of emissions. In PAGE and FUND step 4 focuses on
the damages attributed to the US region in the models. As noted above, DICE does not explicitly
include a separate US region in the model and therefore, U.S. damages are approximated in step
4 as 10 percent of the global values based on the results of Nordhaus (2017). This exercise
produces 30 separate distributions of the SC-CO2 and SC-N2O for a given year, the product of 3
models, 2 discount rates, and 5 socioeconomic scenarios. Following the approach used by the
IWG, the estimates are equally weighted across models and socioeconomic scenarios in order to
consolidate the results into one distribution for each gas for each discount rate.
A.2 - Treatment of Uncertainty in Interim Domestic SC-CO2 and SC-N2O Estimates
There are various sources of uncertainty in the social cost of greenhouse gas estimates used in
this analysis. Some uncertainties pertain to aspects of the natural world, such as quantifying the
physical effects of greenhouse gas emissions on Earth systems. Other sources of uncertainty are
associated with current and future human behavior and well-being, such as population and
regarding post-2100 baseline CH4 and N2O emissions. See the IWG's summary of its methodology in the docket,
document ID number EPA-HQ-OAR-2015-0827-5886, "Addendum to Technical Support Document on Social
Cost of Carbon for Regulatory Impact Analysis under Executive Order 12866: Application of the Methodology to
Estimate the Social Cost of Methane and the Social Cost of Nitrous Oxide (August 2016)". See also National
Academies (2017) for a detailed discussion of each of these modeling assumptions.
cvn Note that inside the U.S. borders is not the same as accruing to U.S. citizens, which may be higher or lower.
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economic growth, GHG emissions, the translation of Earth system changes to economic
damages, and the role of adaptation. It is important to note that even in the presence of
uncertainty, scientific and economic analysis can provide valuable information to the public and
decision makers, though the uncertainty should be acknowledged and when possible taken into
account in the analysis (National Academies 2013). OMB Circular A-4 also requires a thorough
discussion of key sources of uncertainty in the calculation of benefits and costs, including more
rigorous quantitative approaches for higher consequence rules. This section summarizes the
sources of uncertainty considered in a quantitative manner in the domestic SC-CO2 and SC-N2O
estimates.
The domestic SC-CO2 and SC-N2O estimates consider various sources of uncertainty through
a combination of a multi-model ensemble, probabilistic analysis, and scenario analysis. We
provide a summary of this analysis here; more detailed discussion of each model and the
harmonized input assumptions can be found in National Academies (2017). For example, the
three IAMs used collectively span a wide range of Earth system and economic outcomes to help
reflect the uncertainty in the literature and in the underlying dynamics being modeled. The use of
an ensemble of three different models at least partially addresses the fact that no single model
includes all of the quantified economic damages. It also helps to reflect structural uncertainty
across the models, which stems from uncertainty about the underlying relationships among GHG
emissions, Earth systems, and economic damages that are included in the models. Bearing in
mind the different limitations of each model and lacking an objective basis upon which to
differentially weight the models, the three integrated assessment models are given equal weight
in the analysis.
Monte Carlo techniques were used to run the IAMs a large number of times. In each
simulation the uncertain parameters are represented by random draws from their defined
probability distributions. In all three models the equilibrium climate sensitivity is treated
probabilistically based on the probability distribution from Roe and Baker (2007) calibrated to
the IPCC AR4 consensus statement about this key parameter.0"11 The equilibrium climate
sensitivity is a key parameter in this analysis because it helps define the strength of the climate
response to increasing GHG concentrations in the atmosphere. In addition, the FUND and
PAGE models define many of their parameters with probability distributions instead of point
estimates. For these two models, the model developers' default probability distributions are
maintained for all parameters other than those superseded by the harmonized inputs (i.e.,
equilibrium climate sensitivity, socioeconomic and emissions scenarios, and discount rates).
More information on the uncertain parameters in PAGE and FUND is available upon request.
For the socioeconomic and emissions scenarios, uncertainty is included in the analysis by
considering a range of scenarios selected from the Stanford Energy Modeling Forum exercise,
EMF-22. Given the dearth of information on the likelihood of a full range of future
socioeconomic pathways at the time the original modeling was conducted, and without a basis
for assigning differential weights to scenarios, the range of uncertainty was reflected by simply
weighting each of the five scenarios equally for the consolidated estimates. To better understand
how the results vary across scenarios, results of each model run are available in the docket
cvm Specifically, the Roe and Baker distribution for the climate sensitivity parameter was bounded between 0 and 10
with a median of 3 °C and a cumulative probability between 2 and 4.5 °C of two-thirds.
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(Docket ID No. EPA-HQ-OAR-2017-0355, which is for the EPA Affordable Clean Energy
(ACE) rulemaking).
The outcome of accounting for various sources of uncertainty using the approaches described
above is a frequency distribution of the SC-CO2 and SC-N2O estimates for emissions occurring
in a given year for each discount rate. Unlike the approach taken for consolidating results across
models and socioeconomic and emissions scenarios, the SC-CO2 and SC-N2O estimates are not
pooled across different discount rates because the range of discount rates reflects both
uncertainty and, at least in part, different policy or value judgements; uncertainty regarding this
key assumption is discussed in more detail below. The frequency distributions reflect the
uncertainty around the input parameters for which probability distributions were defined, as well
as from the multi-model ensemble and socioeconomic and emissions scenarios where
probabilities were implied by the equal weighting assumption. It is important to note that the set
of SC-CO2 and SC-N2O estimates obtained from this analysis does not yield a probability
distribution that fully characterizes uncertainty about the SC-CO2 and SC-N2O due to impact
categories omitted from the models and sources of uncertainty that have not been fully
characterized due to data limitations.
Figure 6-6 and Figure 6-7 present the frequency distribution of the domestic SC-CO2 and SC-
N2O estimates, respectively, for emissions in 2030 for each discount rate. Each distribution
represents 150,000 estimates based on 10,000 simulations for each combination of the three
models and five socioeconomic and emissions scenarios.C1X In general, the distributions are
skewed to the right and have long right tails, which tend to be longer for lower discount rates.
To highlight the difference between the impact of the discount rate and other quantified sources
of uncertainty, the bars below the frequency distributions provide a symmetric representation of
quantified variability in the SC-CO2 and SC-N2O estimates conditioned on each discount rate.
The full set of SC-CO2 and SC-N2O results through 2050 is available as part of the Draft TSD
analysis materials.
CD! Although each distribution in Figure 6-6 and Figure 6-7 is based on the full set of model results (150,000
estimates for each discount rate), for display purposes the horizontal axis is truncated with a small percent of the
estimates lying below the lowest bin displayed and above the highest bin displayed, depending on the discount
rate.
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If)
O
O
7% Average = $1
c
.Q
3
E
c/)
o
ro
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O
3% Average = J

Jaar
H
Discount Rate
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~	3%
5 - 95 Percentile
of Simulations
__i
16 20
T"
4	8 12 16 20 24 28 32 36
Interim U.S. Domestic Social Cost of Carbon in 2030 [2015$ / metric ton C02]
40
Figure 6-6 - Frequency Distribution of Interim Domestic SC-CO2 Estimates for 2030 (in 2015$ per metric ton
CO2)
1=
.0
3
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III lliflUnnnnjimnr.-1,
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Discount Rate
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i—r
1—i—i—r
2000
4000
I I i I [
6000	8000
i—i—i—i	1—i—i—i—i—r
10000	12000	14000
Interim U.S. Domestic Social Cost of Nitrous Oxide in 2030 (2015$ / metric ton N20]
Figure 6-7 - Frequency Distribution of Interim Domestic SC-N2O Estimates for 2030 (in 2015$ per metric ton
NzO)
As illustrated by the frequency distributions in Figure 6-6 and Figure 6-7, the assumed
discount rate plays a critical role in the ultimate estimate of the social cost of greenhouse gases.
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This is because CO2 and N2O emissions today continue to impact society far out into the future,cx
so with a higher discount rate, costs that accrue to future generations are weighted less, resulting
in a lower estimate. Circular A-4 recommends that costs and benefits be discounted using the
rates of 3 percent and 7 percent to reflect the opportunity cost of consumption and capital,
respectively. Circular A-4 also recommends quantitative sensitivity analysis of key
assumptions00, and offers guidance on what sensitivity analysis can be conducted in cases where
a rule will have important intergenerational benefits or costs. To account for ethical
considerations of future generations and potential uncertainty in the discount rate over long time
horizons, Circular A-4 suggests "further sensitivity analysis using a lower but positive discount
rate in addition to calculating net benefit using discount rates of 3 and 7 percent" (page 36) and
notes that research from the 1990s suggests intergenerational rates "from 1 to 3 percent per
annum" (OMB 2003). We consider the uncertainty in this key assumption by calculating the
domestic SC-CO2 and SC-N2O based on a 2.5 percent discount rate, in addition to the 3 and 7
percent used in the main analysis. Using a 2.5 percent discount rate, the average domestic SC-
CO2 and SC-N2O estimates across all the model runs for emissions occurring in 2030 is $11 per
metric ton of CO2 (2015$) and $3,600 per metric ton of N2O, respectively™1; in this case the
total domestic climate benefits of Scenario 3 are $0.9 million in 2030 under a 2.5 percent
discount rate. The total present value of the domestic climate benefits under a 2.5 percent
discount rate is $10 million.
In addition to the approach to accounting for the quantifiable uncertainty described above, the
scientific and economics literature has further explored known sources of uncertainty related to
estimates of the social cost of carbon and other greenhouse gases. For example, researchers have
examined the sensitivity of IAMs and the resulting estimates to different assumptions embedded
in the models (see, e.g., Hope 2013, Anthoff and Tol 2013, Nordhaus 2014, and Waldhoff et al.
2011, 2014). However, there remain additional sources of uncertainty that have not been fully
characterized and explored due to remaining data limitations. Additional research is needed to
expand the quantification of various sources of uncertainty in estimates of the social cost of
carbon and other greenhouse gases (e.g., developing explicit probability distributions for more
inputs pertaining to climate impacts and their valuation). On the issue of intergenerational
discounting, some experts have argued that a declining discount rate would be appropriate to
analyze impacts that occur far into the future (Arrow et al., 2013). However, additional research
and analysis is still needed to develop a methodology for implementing a declining discount rate
and to understand the implications of applying these theoretical lessons in practice.
cx Although the atmospheric lifetime of CH4 is notably shorter than that of CO2 or N2O, the impacts of changes in
contemporary CH4 emissions are also expected to occur over long time horizons that cover multiple generations.
For more discussion, see document ID number EPA-HQ-OAR-2015-0827-5886, "Addendum to Technical
Support Document on Social Cost of Carbon for Regulatory Impact Analysis under Executive Order 12866:
Application of the Methodology to Estimate the Social Cost of Methane and the Social Cost of Nitrous Oxide
(August 2016)".
CX1 "If benefit or cost estimates depend heavily on certain assumptions, you should make those assumptions explicit
and carry out sensitivity analyses using plausible alternative assumptions." (OMB 2003, page 42).
cxn The estimates are adjusted for inflation using the GDP implicit price deflator. SC-CO2 estimates are rounded to
the nearest dollar and SC-CH4 and SC-N2O estimates are rounded to two significant digits.
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Recognizing the limitations and uncertainties associated with estimating the social cost of
greenhouse gases, the research community is continuing to explore opportunities to improve
estimates of SC-CO2 and other greenhouse gases. Notably, the National Academies of Sciences,
Engineering, and Medicine conducted a multi-discipline, multi-year assessment to examine
potential approaches, along with their relative merits and challenges, for a comprehensive update
to the current methodology. The task was to ensure that the SC-CO2 estimates that are used in
Federal analyses reflect the best available science, focusing on issues related to the choice of
models and damage functions, climate science modeling assumptions, socioeconomic and
emissions scenarios, presentation of uncertainty, and discounting. In January 2017, the
Academies released their final report, Valuing Climate Damages: Updating Estimation of the
Social Cost of Carbon Dioxide,cxm and recommended specific criteria for future updates to the
SC-CO2 estimates, a modeling framework to satisfy the specified criteria, and both near-term
updates and longer-term research needs pertaining to various components of the estimation
process (National Academies 2017). Since the framework used to estimate SC-N2O is the same
as that used for SC-CO2, the Academies' recommendations on how to update many of the
underlying modeling assumptions also apply to the SC-N2O estimates.
The 2017 National Academies report also provides recommendations pertaining to
discounting, emphasizing the need to more explicitly model the uncertainty surrounding discount
rates over long time horizons, its connection to uncertainty in economic growth, and, in turn, to
climate damages using a Ramsey-like formula (National Academies 2017). These and other
research needs are discussed in detail in the 2017 National Academies' recommendations for a
comprehensive update to the current methodology, including a more robust incorporation of
uncertainty.
The Academies' report also discussed the challenges in developing domestic SC-CO2
estimates, noting that current integrated assessment models do not model all relevant regional
interactions - i.e., how climate change impacts in other regions of the world could affect the
United States, through pathways such as global migration, economic destabilization, and political
destabilization. The Academies concluded that it "is important to consider what constitutes a
domestic impact in the case of a global pollutant that could have international implications that
impact the United States. More thoroughly estimating a domestic SC-CO2 would therefore need
to consider the potential implications of climate impacts on, and actions by, other countries,
which also have impacts on the United States." (National Academies 2017, pg. 12-13). This
challenge is equally applicable to the estimation of the domestic SC-CH4 and SC-N2O.
A.3 - Global Climate Benefits
In addition to requiring reporting of impacts at a domestic level, OMB Circular A-4 states that
when an agency " evaluate [s] a regulation that is likely to have effects beyond the borders of the
United States, these effects should be reported separately" (page 15).CX1V This guidance is
cxm National Academies of Sciences, Engineering, and Medicine. 2017. Valuing Climate Damages: Updating
Estimation of the Social Cost of Carbon Dioxide. National Academies Press. Washington, DC Available at
https://www.nap.edu/catalog/24651/valuina-cliniate-daniages-updating-estiniation-of-the-social-cost-of (last
accessed March 20, 2020).
CX1V While Circular A-4 does not elaborate on this guidance, the basic argument for adopting a domestic only
perspective for the central benefit-cost analysis of domestic policies is based on the fact that the authority to
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relevant to the valuation of damages from GHGs, given that most GHGs contribute to damages
around the world independent of the country in which they are emitted. Therefore, in this section
we present the global climate benefits from this rulemaking using the global SC-CO2 and SC-
N2O estimates - i.e., reflecting quantified impacts occurring in both the U.S. and other
countries—corresponding to the model runs that generated the domestic SC-CO2 and SC-N2O
estimates used in the main analysis. The average global SC-CO2 and SC-N2O estimate across
all the model runs for emissions occurring in 2030 are $7/mtC02 (in 2015 dollars) and
$3,500/mtN20, respectively, using a 7 percent discount rate, and $57/mtC02 and $21,000/mtN20
using a 3 percent discount rate.cxv The domestic estimates presented above are approximately
15-19 percent and 12-14 percent of the global estimates for the 7 percent and 3 percent discount
rates, respectively, depending on the gas. Applying these estimates to the changes in CO2 and
N2O emissions results from Scenario 3 in estimated total global climate benefits of $0.6 million
in 2030, using a 7 percent discount rate. The total present value of the global climate benefits
using a 7 percent discount rate is $3.5 million. The estimated total global climate benefits are
$4.7 million in 2030 using a 3 percent rate. The total present value of the global climate benefits
using a 3 percent discount rate is $49 million. Under the sensitivity analysis considered above
using a 2.5 percent discount rate, the average global estimates across all the model runs for
emissions occurring in 2030 are $82/mtC02 (in 2015 dollars) and $30,000/mtN20. The total
global climate benefits are estimated to be $6.8 million in 2030 using a 2.5 percent discount rate.
The total present value of the global climate benefits using a 2.5 percent discount rate is $77
million. All estimates are reported in 2015 dollars.
regulate extends only, or principally, to a nation's own residents who have consented to adhere to the same set of
rules and values for collective decision-making, as well as the assumption that most domestic policies will have
negligible effects on the welfare of other countries' residents (EPA 2010; Kopp et al. 1997; Whittington et al.
1986). In the context of policies that are expected to result in substantial effects outside of U.S. borders, an active
literature has emerged discussing how to appropriately treat these impacts for purposes of domestic policymaking
(e.g., Gayer and Viscusi 2016, 2017; Anthoff and Tol, 2010; Fraas et al. 2016; Revesz et al. 2017). This discourse
has been primarily focused on the regulation of greenhouse gases (GHGs), for which domestic policies may result
in impacts outside of U.S. borders due to the global nature of the pollutants.
cxv The estimates are adjusted for inflation using the GDP implicit price deflator and then rounded to two significant
digits.
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REFERENCES
59 U.S. EPA, 2015: Proposed Finding that Greenhouse Gas Emissions from Aircraft Cause or Contribute to Air
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60ICAO, 2016: Report of Tenth Meeting, Montreal, 1-12 February 2016, Committee on Aviation Environmental
Protection, Document 10069, CAEP/lO^ 432pp, Available for purchase at:
http://www.icao.int/publications/Pages/ca talogue.aspx (last accessed March 18, 2020). The ICAO CAEP/10 report
is found on page 27 of the English Edition 2020 catalog and is copyright protected: Order No. 10069. The summary
of the ten stringency options is located in Appendix C (starting on page 5C-1) of this report.
61 PIANO (Project Interactive Analysis and Optimization), Aircraft Design and Analysis Software by Dr. Dimitri
Simos, Lissys Limited, UK, 1990-present; Version 5.4, February 21, 2017. Available at www.piaiio.aero (last
accessed March 18, 2020). This is a commercially available aircraft design and performance software suite used
across the industry and academia. This model contains non-manufacturer provided estimates of performance of
various aircraft.
62ICF, 2018: Aircraft COi Cost and Technology Refresh and Industry Characterization, Final Report, EPA Contract
Number EP-C-16-020, September 30, 2018.
63 Within this endnote are the references for the discussion in the Appendix of Chapter 6.
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Anthoff, D., and R. J. Tol. 2010. On international equity weights and national decision making on climate change.
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T. Sterner, R.S.J. Tol, and M. Weitzman. 2013. "Determining Benefits and Costs for Future Generations." Science,
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Fraas, A., R. Lutter, S. Dudley, T. Gayer, J. Graham, J.F. Shogren, and W.K. Viscusi. 2016. Social Cost of Carbon:
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Gayer, T., and K. Viscusi. 2016. Determining the Proper Scope of Climate Change Policy Benefits in U.S.
Regulatory Analyses: Domestic versus Global Approaches. Review of Environmental Economics and Policy, 10 (2):
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Gayer, T., and K. Viscusi. 2017. The Social Cost of Carbon: Maintaining the Integrity of Economic Analysis—A
Response to Revesz et al. (2017). Review of Environmental Economics and Policy, 11(1): 174-5.
Hope, Chris. 2013. "Critical issues for the calculation of the social cost of CO2: why the estimates from PAGE09 are
higher than those from PAGE2002." Climatic Change, 117: 531-543.
Institute of Medicine of the National Academies. 2013. Environmental Decisions in the Face of Uncertainty.
National Academies Press. Washington, DC.
Kopp, R.J., A.J. Krupnick, andM. Toman. 1997. Cost-Benefit Analysis and Regulatory Reform: An Assessment of
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Estimation of the Social Cost of Carbon Dioxide. National Academies Press. Washington, DC Available at
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the Administrator. EPA 240-R-10-001 December 2010. Available at: 
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Regulatory Flexibility Analysis
Table of Contents
Chapter 7 Regulatory Flexibility Analysis	
7.1	Requirements of the Regulatory Flexibility Act	
7.2	Need for the Rulemaking and Rulemaking Objectives	
7.3	Definition and Description of Small Entities	
7.4	Summary of Small Entities to Which the Rulemaking Will Apply	
7.5	Related Federal Rules	
7.6	Projected Reporting, Recordkeeping, and Other Compliance Requirements
7.7	Projected Effects of the Proposed Rulemaking on Small Entities	
7.8	Regulatory Alternatives to Accommodate Small Entities	
Table of Tables
Table 7-1 - Small Business Definitions	
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Chapter 7 Regulatory Flexibility Analysis
This chapter presents our Small Business Flexibility Analysis (SBFA) which evaluates the
potential impacts of the proposed rule on small entities. The Regulatory Flexibility Act (RFA),
as amended by the Small Business Regulatory Enforcement Fairness Act of 1996 (SBREFA),
generally requires an agency to prepare a regulatory flexibility analysis of any rule subject to
notice and comment rulemaking requirements under the Administrative Procedure Act or any
other statute unless the agency certifies that the rule will not have a significant economic impact
on a substantial number of small entities.
7.1 Requirements of the Regulatory Flexibility Act
When proposing and promulgating rules subject to notice and comment under the Clean Air
Act, we are generally required under the RFA to conduct a regulatory flexibility analysis unless
we certify that the requirements of a regulation will not cause a significant impact on a
substantial number of small entities. The key elements of the RFA include:
•	a description of and, where feasible, an estimate of the number of small entities to which
the proposed rule will apply;
•	the projected reporting, record keeping, and other compliance requirements of the
proposed rule, including an estimate of the classes of small entities which will be subject
to the requirements and the type of professional skills necessary for preparation of the
report or record;
•	an identification to the extent practicable, of all other relevant Federal rules which may
duplicate, overlap, or conflict with the proposed rule; and,
•	any significant alternatives to the proposed rule which accomplish the stated objectives of
applicable statutes and which minimize any significant economic impact of the proposed
rule on small entities.
The RFA was amended by SBREFA to ensure that concerns regarding small entities are
adequately considered during the development of new regulations that affect them. Although we
are not required by the Clean Air Act to provide special treatment to small businesses, the RFA
requires us to carefully consider the economic impacts that our proposed rules will have on small
entities. Specifically, the RFA requires us to determine, to the extent feasible, our rule's
economic impact on small entities, explore regulatory options for reducing any significant
economic impact on a substantial number of such entities, and explain our ultimate choice of
regulatory approach.
In developing this proposed rule, we concluded that the airplane and airplane engine GHG
program under consideration would not have a significant impact on a substantial number of
small entities. We based this on the fact that the proposed rule does not place any burden on
small governmental jurisdictions or small nonprofit organizations. Further, there is only one
small business in the group of potentially affected entities - an airplane engine manufacturer.
The only economic burden associated with this proposed rule is that associated with the annual
reporting requirement. This proposed reporting requirement would only apply to airplane
manufacturers, and thus would not impact the single small airplane engine manufacturer.
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7.2	Need for the Rulemaking and Rulemaking Objectives
A detailed discussion on the need for and objectives of this proposed rule is located in the
preamble to the proposed rule. The standards proposed in this rule are the equivalent of the
ICAO standards, consistent with U.S. efforts to secure the highest practicable degree of
uniformity in aviation regulations and standards In addition, EPA is required by Clean Air Act
section 231 to propose and promulgate emission standards regulating GHG emissions from the
classes of aircraft engines identified in EPA's 2016 final endangerment and cause/contribute
findings for those emissions. EPA is proposing to meet the Clean Air Act obligation by adopting
GHG standards which are equivalent to the Airplane CO2 Emission Standards adopted by ICAO.
7.3	Definition and Description of Small Entities
Small entities include small businesses, small organizations, and small governmental
jurisdictions. For the purposes of assessing the impacts of the proposed rule on small entities, a
small entity is defined as: (1) a small business that meets the definition for business based on the
Small Business Administration's (SBA) size standards (see Table 7-1); (2) a small governmental
jurisdiction that is a government of a city, county, town, school district or special district with a
population of less than 50,000; and (3) a small organization that is any not-for-profit enterprise
which is independently owned and operated and is not dominant in its field. Table 7-1 provides
an overview of the primary SBA small business categories potentially affected by this regulation.
Table 7-1 - Small Business Definitions
Industry
Defined as small entity by SBA
if:
NAICS
Codes3
Manufacturers of new airplane
engines
<1,500 employees
336412
Manufacturers of new airplanes
<1,500 employees
336411
a. North American Industry Classification System (NAICS)
7.4 Summary of Small Entities to Which the Rulemaking Will Apply
The businesses that are potentially affected by this proposed rule are those that manufacture
new airplanes and new airplane engines. As outlined in Chapter 1, we performed an industry
characterization of potentially affected airplane and airplane engine manufacturers.
The industry characterization was used to determine which airplane and airplane engine
manufacturers would also meet the SBA definition of a small business under this proposal. From
the industry characterization, we determined that there is only a single airplane engine
manufacturer that meets the definition of a small business. Given the small number of
businesses overall that are potentially affected by this proposed rule as well as the relative
stability of the commercial aviation market, the EPA is confident that this accounting of the
number of potentially affected small businesses is both correct and unlikely to change in the near
future.
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7.5	Related Federal Rules
We are not aware of any area where the regulations under consideration would directly
duplicate or overlap with the existing federal, state, or local regulations; however, one small
engine manufacturer is also subject to the airplane engine smoke emissions control requirements.
The FAA will follow this proposed action, if finalized, with its own rulemaking to incorporate
the adopted standards into its certification and compliance framework.
7.6	Projected Reporting, Recordkeeping, and Other Compliance Requirements
Although the EPA has the authority in the U.S. for the development of emissions regulations
for airplanes and airplane engines, the FAA, through the type certification process, is the entity
which ensures that compliance obligations are met. Thus, the reporting requirements associated
with the proposed rule are limited to the proposed annual reporting requirement and do not
extend to compliance and its associated recordkeeping.
The proposed annual reporting requirements are similar in style to those currently in place for
the emissions of criteria pollutants and smoke from airplane engines. However, they differ in
substance given the fundamentally different nature of the current airplane engine emission
standards and test procedures compared to proposed GHG regulations for airplanes and airplane
engines. Further, these proposed new requirements would be met by the airplane manufacturers,
as opposed to the current requirements which are met by the airplane engine manufacturers.
These proposed reporting provisions include:
•	Company name and reporting period;
•	name and characteristics of each airplane type reported;
•	production volumes for each reported airplane type for the previous calendar year;
•	fuel efficiency metric value, as well as specific parameters used to derive the metric
value; and
For a more detailed discussion of these provisions, please see section V of the preamble to
this proposed rule as well as the draft Information Collection Request, available in the public
docket.
7.7	Projected Effects of the Proposed Rulemaking on Small Entities
After considering the economic impacts of today's proposed rule on small entities, we do not
believe that this action will have a significant economic impact on a substantial number of small
entities.
The only economic burden associated with this proposed rule is the minimal recordkeeping
burden associated with the annual reporting requirement. Given that the reporting requirement
would only apply to airplane manufacturers, the one small airplane engine manufacturer would
not be impacted by the sole economic burden of the proposed rule.
7.8	Regulatory Alternatives to Accommodate Small Entities
Given that the EPA does not believe the proposed rule would have any impact on even a
single small entity, it does not believe there is a need to develop regulatory alternatives to help
minimize such a burden on small entities.
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REFERENCES
There are no references for this chapter.
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