EDA Enn'~,al Protection ^\XSmartWaV
LhI # % Agency Environmental Protection Agency^
2022 SmartWay Air
Carrier Partner Tool
Air Tool Technical
Documentation
U.S. Version 2.0.21 (Data Year 2021)
EPA-420-B-22-008 I February 2022 I SmartWay Transport Partnership I epa.gov/smartway
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* mAgency U.S. Environmental Protection Agency^
2022 SmartWay Air
Carrier Partner Tool:
Air Tool Technical
Documentation
U.S. Version 2.0.21
(Data Year 2021)
Transportation and Climate Division
Office of Transportation and Air Quality
U.S. Environmental Protection Agency
EPA-420-B-22-008
February 2022
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Table of Contents
1.0 OVERVIEW l
2.0 DATA INPUTS AND SOURCES 2
2.1 AvaiLabLe Emission Factors 2
2.2 Aircraft Activity Data 3
2.3 Aircraft Characterization Data 4
3.0 EMISSION ESTIMATION 6
3.1 Emission CaLcuLations Based on FueL Consumption Data 6
3.2 Emission CaLcuLations Based on Aircraft-specific Data 6
3.3 Aircraft UpLoad Function 8
4.0 PERFORMANCE METRICS 10
4.1 Grams Per MiLe 10
4.2 Grams per Ton-MiLe 10
4.3 PubLic DiscLosure Reports 10
5.0 DATA VALIDATION 11
REFERENCES 12
APPENDIX A: MODELING METHODOLOGY FOR N0X AND PM EMISSIONS A-l
List of Tables
Table 1. Fuel-based Factors (g/kg of fuel) 2
Table 2. Activity Data Sources 3
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Overview
This document provides detailed background information on the data sources, calculation methods, and
assumptions used within the SmartWay Air Tool, version 2.0.21. The SmartWay Air Tool utilizes up-to-date
emission factors, in combination with detailed aircraft activity data, to estimate emissions and associated
performance metrics. The primary purpose of the Tool is to help fleets calculate actual pollutant emissions
for specific aircraft types and track their emissions performance over time. Shippers can, in turn, use the data
that air carriers report using these Tools to develop more advanced emissions inventories associated with
their freight activity and to track their emissions performance over time.
The Tool allows the user to evaluate fleet performance in terms of different mass-based performance
metrics for C02, NOx, and PM (PM10 and PM2,5):
Grams per mile
^ Grams per average payload ton-mile
Fleet performance can be assessed on a fleet or fuel-type basis, or on an aggregated basis across all fleets
and fuels. By collecting detailed information on fleet operations air carriers can compare their performance
to other, similar carriers, which can help them to better manage their emissions performance.
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Data Inputs and Sources
Similar to the other SmartWay tools, air carrier partners provide information concerning fuel usage and
aircraft activity including landing and take-off cycles (LTOs) and hours of operation in order to estimate C02,
NOx and PM2.5 emissions, and to account for performance improvements made to their fleets over time.
The approach used to estimate C02 emissions associated with aircraft operations focuses on total fuel usage.
NOx and PM2.5 emissions are estimated using detailed information about fleet composition and operations.
Most airlines provide aircraft-specific activity data to the Federal Aeronautics Administration (FAA). To reduce
the burden to Partners, the data elements required for this Tool are similar to the data already being reported
to the FAA.
2.1 AVAILABLE EMISSION FACTORS
Currently there are two types of aircraft engines used for non-military operations: aircraft equipped with
turbine engines that use jet fuel, and smaller aircraft equipped with piston-driven engines that use aviation
gasoline. The emission factors used for the fuel-based emission estimates are presented in Table 1.
Table 1. Fuel-based Factors (g/kg of fuel)
I
Fuel
g C02 per kg fuel
Jet Fuel
3.155
Aviation Gas
3.146
Note: Alternative fuels such as Sustainable Aviation Fuels (SAF) are currently being considered for
commercial aviation applications. Only recently have these fuels received certification for aviation use at
concentrations up to 50 percent. These fuels are being tested in pilot projects and have yet to be fully
commercialized, which is expected to take several years as infrastructure issues related to the distribution
and storage of these fuels are addressed. As results concerning the performance and associated emissions
of these alternative fuels are released, these data will be evaluated for possible inclusion in future versions of
the SmartWay Air Tool.
The preferred approach for estimating NOx and PM2,5 is based on hours of operation and LTO activity data.1
Therefore, fuel-based emission factors are not used for these pollutants. NOx and PM2,5 emissions are based
on aircraft-specific data obtained from the FAA's Aviation Environmental Design Tool (AEDT). The fuel usage
and emission factor data in AEDT are obtained from the International Civil Aviation Organization (ICAO)
Aircraft Engine Databank and adjusted to account for the airframe to which the engine is applied. The NOx
1 PM10 is assumed to be 102.5% of PM2.5 for jet fuel, and 145.0% of PM2.5 for aviation gasoline, as per the EPA 2017 National Emissions Inventory. See
https://www.epa.aov/air-emissions-inventories/2Ql7-nationaL-emissions-inventorv-nei-data. Accessed 1-7-2021.
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and PM2.5 emission factors have been updated using the AEDT model, version 2d. ALL current aircraft and
engines incLuded in version 2d have been added to the Air T00L.
The ICAO testing cycLe focused on airport-reLated emissions. As such, onLy data on approach, Landing, taxi-in,
idLe, taxi-out, takeoff, and cLimbout modes were coLLected. Emission factors for cruising are not provided in
the ICAO test data, nor are they caLcuLated in AEDT. For the SmartWay Air Tool cruising emissions are
caLcuLated based on the assumption that the aircraft engines operate at a percent of take-off engine Loads
(i.e., maximum thrust), as specified by the user (see Engine Load % on the Aircraft Inventory worksheet of the
T00L).
BLack carbon (BC) emission estimates for jet fueL are assumed to equaL 13% of PM2.5 emissions.2 BC emissions
associated with aviation gasoLine are assumed to equaL those of unLeaded on-road gasoLine, caLcuLated by
muLtipLying aviation gasoLine gaLLons by 0.050 grams/gaLLon.3'4
2.2 AIRCRAFT ACTIVITY DATA
Two types of activity data are required for the SmartWay Air T00L: data used to estimate emissions (e.g., fueL
usage, hours of operation, and LTOs) and data needed to deveLop performance metrics (e.g., miLes traveLed,
ton-miLes, cargo payLoad, utiLization rates). Much (though not aLL) of the data needed for this T00L are pubLicLy
reported, as summarized in TabLe 2. Some non-reported data, such as ton-miLes, wiLL aLso need to be
provided.
Table 2. Activity Data Sources
Activity Measure
Reporting Form
TranStats Database
FueL Consumption
P-12A e
ScheduLe P-12A
F-2 d
AvaiLabLe on request
LTOs
T-100 and T-ioo(f) a
T-100 Segment (ALL Carriers)
Distance Between Airports
T-100 and T-ioo(f) a
T-100 Segment (ALL Carriers)
Passengers T ransported
T-100 and T-ioo(f) a
T-100 Segment (ALL Carriers)
Mail Transported
T-100 and T-ioo(f) a
T-100 Segment (ALL Carriers)
Freight Transported
T-100 and T-ioo(f) a
T-100 Segment (ALL Carriers)
Operating Revenue
P-1.2 b
ScheduLe P-12
P-1.1 c
ScheduLe P-11
F-id
AvaiLabLe on request
a Forms are submitted monthLy by foreign, Large certificated, commuter and smaLL certificated carriers (14 CFR Parts 217,
241, 298). Foreign T-ioo(f) data are heLd confidentiaL for six months. SmaLL carrier data are heLd confidentiaL for two and
a haLf months.
b Forms are submitted quarterLy by Large certificated carriers with annuaL operating revenues of $20 miLLion or more.
Foreign carriers are not required to report financiaLs. Large carrier financiaL data (P-1.2 and P-1.1) are heLd confidentiaL
2 Eastern Research Group, North American BLack Carbon Emissions Estimation Guidelines. Prepared for the Commission on Environmental Cooperation, May
2015.
3 Ibid.
4 Unlike today's on-road gasoLine, aviation gasoLine contains tetra-ethyL Lead as an additive. The addition of Lead increases gasoLine octane ratings which in
turn may decrease BC emissions. Accordingly, the BC emissions assumed for aviation gasoLine may be overestimated to some extent.
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for two and a half months.
c Forms submitted semiannually by large certificated carriers with annual operating revenues of less than $20 million.
d Forms submitted quarterly by commuter and small certificated carriers. Small carrier financials and fuel consumption
data (F-i and F-2) are held confidential for 3 years. Small certificated and commuter carriers are defined by the size of
planes in their fleet and the number of trips per week.
e Forms submitted monthly by large certificated carriers with annual operating revenues of $20 million or more. Foreign
carriers are not required to report fuel usage.
For NOx and PM2.5, emissions at and near airports are estimated for individual aircraft by applying annual,
aircraft-specific LTOs to the LTO emission factors obtained from the AEDT model (see Section 2.2.1). Because
aircraft trip lengths can vary significantly, total hours of operation are required to estimate the time spent in
cruising mode. The total time associated with annual LTO activities are subtracted from the reported total
annual hours to avoid double counting.
As noted above, C02 emissions are simply based on the amount of fuel used by the partner annually. For NOx
and PM2.5, the two key data elements required to estimate emissions are the aircraft make and model and
the associated engine make and model. As any given aircraft model can be equipped with a wide range of
engines that have different fuel consumption and emission rates, it is important that partners provide as
much detailed information as possible about the engines used in their fleet. In the newest version on
AEDTfcd) there are an approximate total of 2,912 aircraft and engine combinations. Many of these aircraft are
not used to carry freight though (e.g., military aircraft), and have been excluded from the Air Tool. The list of
the possible aircraft and engine combinations are available in the AirTool-Aircraft-Engine-Data.xlsx file,
available from EPA upon request.
If partners do not know the engine for their aircraft, the Tool will identify default engines for each aircraft. For
an engine to be designated as a default for a particular aircraft make and model, a valid aircraft engine
combination should first be identified in the AEDT dataset. In some cases, there is only one engine listed per
aircraft make/model in AEDT. For those aircraft, the one available engine is simply designated as the default
engine. For other aircraft, Ascends activity data are used to determine which engines are the most common
for each aircraft. If an engine listed in Ascends is not in AEDT, the next most common engine is used instead.
If there is no match with the Ascends data, AEDT also has defaults listed as well as the prior generation
EDMS software from FAA. Additional internet search results provided the basis for determining the default
engine for some aircraft.
Default engines are designated by a "1" in the Default column in the AirTool-Aircraft-Engine-Data.xlsx file.
In addition, to accurately represent a partner's performance metrics the Air Tool estimates aircraft capacity in
units of mass for 2,619 individual aircraft-engine combinations. In October 2014, using Jane's Transportation
Reference Guide, Aviation Week's Aerospace & Defense Sourcebook, and other online resources, capacities
for the individual aircraft were reviewed and over 125 corrections were made. Current capacities were quality
checked by comparing the ratio of capacity and aircraft length, for similar sized aircraft. Capacity corrections
were made calculated ratios were outside an acceptable range.
2.3 AIRCRAFT CHARACTERIZATION DATA
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When weight capacity was clearly defined, values were chosen that reflected total passenger and luggage
weight (military aircraft totals included munitions). Note that there are often inconsistencies in how capacities
are defined, however, leading to uncertainty in these assignments. For this reason, partners are encouraged
to input their own estimates for weight capacity if available.
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Emission Estimation
Within the SmartWay Air Tool a fuel-based approach is used for the calculation of C02 while an operations-
based approach is used for calculating NOx and PM2.5.
3.1 EMISSION CALCULATIONS BASED ON FUEL CONSUMPTION DATA
C02 emissions are estimated using the following equation:
EM = FUa* FCx EFa
Where:
EM = Emission estimate for C02 (grams per year)
FUa = Reported fuel use (gallons/year or tons/year) for fuel type a
FC = Fuel conversion factor for gallons to kilograms (Jet Fuel = 3.07 kilogram/gallon;
aviation gasoline 2.73 kilogram/gallon); tons of fuel to kilograms (1 ton = 907.18
kilograms)
EFa = Emission factor for fuel type a (grams/kilogram of fuel) - Table 1
a = Fuel type (e.g., jet fuel or aviation gasoline)
3.2 EMISSION CALCULATIONS BASED ON AIRCRAFT-SPECIFIC DATA
The operations-based approach allows for NOx and PM2.5 emissions to account for individual aircraft in the
partner's fleet. The emissions calculation is developed using two types of aircraft operations: 1) airport-
related activities (i.e., approach, landing, taxi-in, idle, taxi-out, take-off, and climbout), which are quantified in
terms of LTO cycles, and 2) cruising operations between airports, measured in hours.
Airport-related Activities
LTO data can be applied to aircraft-specific fuel-consumption and emission factors, which were developed
from data extracted from the FAA's AEDT database. Within the Air Tool, aircraft engine emissions data are
applied to time-in-mode data for each segment of the LTO cycle, providing aircraft-specific LTO-based
emission factors.
AEDT uses fuel-based indexes to estimate emissions, which means the time-in mode values are linked to
fuel usage rates, which in turn vary based on aircraft model/engine combinations. These fuel usage rates are
built into the AEDT model, which then calculates the emissions based on fuel usage. A detailed description
of the methodology for modeling mode-specific emission factors can be found in Appendix A.
User-provided aircraft-specific LTO activity data (under Total Annual LTOs on the Aircraft Operations screen)
is applied to the LTO emission factors using the following equation:
I
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EAxp - LT Ox x E F i_xp
EAxp = Airport-related aircraft emissions for specific aircraft model and engine combination
(x) and pollutant (p) (grams per year)
LTOx = Annual LTO activity for specific aircraft (x) (LTOs/year)
EFd
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X
70
EFcxp
3,600
P
Total cruising hours of operation for specific aircraft x (hours/year)
Cruising emission factor for specific aircraft (x) and pollutant (p) (grams / second)
Conversion seconds per hour
Load factor specified for each aircraft make/model (x), in percent
Default engine load factor percent for cruising operations from AEDT
Specific aircraft make and model
Pollutant
Additional information on the emission factors used for the cruising mode can be found in the AirTool-
Aircraft-Engine-Data.xlsx file.
Once LTO and cruising emissions are calculated they are summed to determine total emissions for each
aircraft.
The Air Tool provides an upload function which allows the user to import hundreds or thousands of records
for individual aircraft, including the engine characteristic and activity data needed to estimate emissions and
performance metrics. The Air Tool aggregates the import file to the aircraft/engine level. To perform this
aggregation, the Tool weights the reported engine loads by total fuel consumption for the given
aircraft/engine category. Similarly, individual weight capacity values (in pounds) are weighted by the relative
fraction of ton-miles for the category. Note that this approach only impacts the reported performance
metrics, not the calculated mass emissions.
The SmartWay Air Tool is provided with an Excel file named "starter file.xls" which should be populated with
aircraft-specific data for upload.5 Users can provide one record for each aircraft make/model/engine
make/model combination. Each record should include data for the following columns:
# aircraft
Fuel Type
Fuel Units
fuel usage
total miles
total ton-miles
^ LTOs
operating hours
weight capacity
5 Users may export a starter file template from the Tool's Import Aircraft screen.
3 3 AIRCRAFT UPLOAD FUNCTION
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The first rows of the starter file contain example inputs for user reference. These rows should be over-written
with actual data before importing into the Air Tool. Please be sure to save the updated file using the same
name and Excel file format as the original starter file.
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Performance Metrics
SmartWay Air Tool is designed to apply calculated emissions to different operational metrics. These metrics
can be used as reference points to evaluate a partner's environmental performance relative to others. The
equations used to estimate the different performance metrics are shown below.
4-1 GRAMS PER MILE
PMp = X EMpo / M
Where:
PMp = Grams of pollutant per mile (grams/mile)
EM po = Total annual emissions summed by pollutant (P) for both operation types (O) (grams
per year)
M = Total annual statute miles flown
P = Pollutant
O = Operation types (airport and cruising)
4.2 GRAMS PER TON-MILE
PTMp = I Epto / TM
Where:
PTMp = Grams of pollutant per ton-mile (grams/ton-mile)
Epo = Annual emissions summed over operation type (O) by pollutant (P) (grams/year)
TM = Total annual ton-miles
P = Pollutant
O = Operations (airport and cruising)
4 3 PUBLIC DISCLOSURE REPORTS
The Air Tool provides a report summarizing Scope l emissions for public disclosure purposes. Mass
emissions are presented in metric tonnes for C02, NOx, and PM2,56 for all fleets.
6 Emissions from CH4, N20, HFC's, PFC's, SF6 and NF3 have been deemed immaterial, comprising Less than 5% of overall GHG emissions and are therefore
EXCLUDED for reporting purposes.
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M Data Validation
Validation checks are performed for air carrier average payload entries. First, payloads that are more than
twice the value reported for a given aircraft make/model/series elicit a warning from the tool, although
these values do not have to be changed. In addition, the maximum average payload is set to 58 tons for all
carriers, corresponding to the maximum payload capacity for the largest aircraft make/model specified by
SmartWay partners. Payloads above this amount trigger an out of range error that must be addressed by the
partner in order to proceed. Payloads between 29 and 58 tons will receive a warning which do not have to be
addressed if the partner so chooses.
Range checks are also performed to ensure the relationship between miles per hour (mph), hours per LTO,
and miles per LTO are reasonable for each make/model/series combination. Values outside the following
ranges result in a warning message requesting the user check and confirm their data entries.
^ 200 <= mph <= 700
^ 0.5 <= hours/LTO <= 12.5
100 <= miles/LTO <= 8,750
The upper end of the mph range is based on the maximum speed of the Boeing 777-200 series (682), a high-
speed cargo plane.7 The low-end mph value is placed slightly above typical stall speeds for large jets (150).
The upper end of the hour per LTO range is based on the longest scheduled commercial cargo flight
identified (UPS Louisville to Dubai, 12.5 hours).8 The low-end hour per LTO value was assumed at one half
hour for short haul cargo flights.
High and low miles per LTO values were calculated by multiplying the high/low miles per LTO values by the
corresponding mph values.
7 See https://www.quora.com/What-is-the-fastest-carao-pLane-on-earth. Accessed 12-29-2021.
8 Airways, UPS to FLy Ultra Long Haul: Non-stop between Louisville and Dubai. February 5, 2018. https://airwavsmaa.com/airlines/ups-unveils-new-non-
stop-fliaht-shipments-u-s-middle-east/. Accessed 12-29-2021.
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References
Ascends
Aircraft and Airline Data, 2012.
Aviation Week & Space Technology
2009 Source Book.
Endres, Gunter, and Gething, Michael
Jane's Aircraft Recognition Guide - Fifth Edition. London: HarperCollins, 2007.
International Civil Aviation Organization
Aircraft Engine Emissions Databank, 2009.
U.S Department of Transportation
Federal Aviation Administration, Aviation Environmental Design Tool Version 2d, February 2017.
U.S Department of Transportation
Federal Aviation Administration, Emission Dispersion and Modeling System Version 5.1.4.1, August 2013.
U.S. Department of Transportation
Federal Aviation Administration, F-iand F-2 Forms
U.S. Department of Transportation
Federal Aviation Administration, P-i Forms
U.S. Department of Transportation
Federal Aviation Administration, T-100 Forms
U.S. Environmental Protection Agency
National Emission Inventory, 2009.
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Appendix A: Modeling Methodology for NOx
and PM Emissions
C02 emissions are calculated from fuel burn in the SmartWay Air Tool, however NOxand PM2.5 emissions are
sensitive to engine operating mode, and so must be estimated by modeling aircraft operations. FAA's
Aviation Environmental Design Tool (AEDT, version 2d) provides aircraft- and airport-specific fuel
consumption and emissions estimates by operating mode. The operations of interest for this tool are LTO
and cruise.
In order to represent the activity of typical freight aircraft, EPA modeled take-offs and landings for all aircraft
listed in the tool at the ten busiest freight airports in the US, and four additional airports that are hubs for the
two air largest carriers in the USA, FedEx and UPS. The airports are listed in Table A-1.9
Table A-i. Busiest Freight Airports - 2015
Rank
City, State
Airport Code
Annual Metric
Tons of Cargo
1
Memphis TN
MEM
4,290,638
2
Anchorage AK
ANC
2,630,701
3
Louisville KY
SDF
2,350,656
4
Miami FL
MIA
2,005,175
5
Los Angeles CA
LAX
1,938,624
6
Chicago IL
ORD
1,592,826
7
New York NY
JFK
1,286,484
8
Indianapolis IN
IND
1,084,857
9
Cincinnati OH
CVG
729.309
10
Newark NJ
EWR
683,760
11
Dallas/Fort Worth TX
DFW
670,029
13
Oakland CA
OAK
511.368
15
Ontario CA
ONT
463.463
19
Philadelphia PA
PHL
427.645
For each aircraft make/model/engine combination, emissions per LTO and time-in-mode for LTO vary from
one airport to another and vary by runway at some airports. For each aircraft in the Air Tool, emissions and
time-in-mode per LTO were calculated for each of the airports in Table A-i. These values were then
averaged across the airports, with the average weighted by Annual Metric Tonnes of Cargo to obtain a single
set of figures for each aircraft that are reasonably representative of the nationwide annual operations for
9 Airports Council international, Airport Traffic Reports, https://aci.aero/20i6/09/09/airports-counciL-internationaL-reLeases-20i5-worLd-airport-traffic-
report-the-busiest-become-busier-the-year-of-the-internationaL-hub-airport/. Accessed 12-29-2021.
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each. The AEDT model and supporting documentation can be found at:
https://aedt.faa.gov/2d information.aspx.
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For more information:
U. S. Environmental Protection Agency
Office of Transportation and Air Quality
1200 Pennsylvania Ave. NW
Washington, DC 20460
(734) 214-4333
www.epa.aov/transportation-air-pollution-and-
climate-chanae
U. S. Environmental Protection Agency
National Vehicle and Fuel Emissions Laboratory
2565 Plymouth Rd.
Ann Arbor, Ml 48105
(734) 214-4200
www.epa.gov/aboutepa/about-national-
vehicle-and-fuel-emissions-laboratory-nvfel
EPA 420 B 22 008 | February 2022 | SmartWay Transport Partnership | epa.gov/smartway
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