^\xSmartWay
Transport Partnership
U.S. Environmental Protection Agency
2017 SmartWay Air Carrier
Partner Tool:
Technical Documentation
U. S. Version 2.0.16 (Data Year 2016)
www.epa.gov/smartway
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United States
Environmental Protection
W * Agency

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"^^SmartWay
Transport Partnership
U.S. Environmental Protection Agency
2017 SmartWay Air Carrier
Partner Tool:
Technical Documentation
U. S. Version 2.0.16 (Data Year 2016)
Transportation and Climate Division
Office of Transportation and Air Quality
U.S. Environmental Protection Agency
United States
Environmental Protection
Agency
Office ofTransportation and Air Quality
E PA-420- B-17-019
April 2017

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2017 SmartWay Air Carrier Partner Tool
Technical Documentation
U.S. Version 2.0.16 (Data Year 2016)
4-14-17
1.0	Data 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 CO2, NOx and PM2.5
emissions, and to account for performance improvements made to their fleets
over time.
The approach used to estimate CO2 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 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.
1.1	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 Emission Factors (g/kg of fuel)
Fuel
g C02 per kg fuel
Jet Fuel
3,155
Aviation Gas
3,146
Note: Alternative fuels such as biojet and synthetic fuels 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.
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The preferred approach for estimating NOx and PM2.5 is based on hours of
operation and LTO activity data. 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 and
PM2.5 emission factors have been updated using the AEDT model, version 2c.
All current aircraft and engines included in version 2c have been added to the Air
Tool.
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 Tool).
1.2 Aircraft Activity Data
Two types of activity data are required for the SmartWay Air Tool: 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 and volume, utilization rates). Much (though not all) of the data needed
for this Tool are publically reported, as summarized in Table 2. Some non-
reported data, such as ton-miles and cargo volume utilization, will also need to
be provided.
Table 2. Activity Data Sources
Activity Measure
Reporting Form
TranStats Database
Fuel Consumption
P-12A6
Schedule P-12A
F-2d
Available on request
LTOs
T-100 and T-100(f)3
T-100 Segment (All
Carriers)
Distance Between Airports
T-100 and T-100(f)3
T-100 Segment (All
Carriers)
Passengers Transported
T-100 and T-100(f)3
T-100 Segment (All
Carriers)
Mail Transported
T-100 and T-100(f)3
T-100 Segment (All
Carriers)
Freight T ransported
T-100 and T-100(f)3
T-100 Segment (All
Carriers)
Operating Revenue
P-1.2b
Schedule P-12
P-1.1 c
Schedule P-11
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Activity Measure
Reporting Form
TranStats Database

F-1d
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-100(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 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-1 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.
1.3 Aircraft Characterization Data
As noted above, CO2 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 AEDT(2c) there are a
total of 4,300 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.xIsx file.
In a future version of the Air Tool, 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 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, internet search results provide the basis for determining
the default engine.
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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 and volume for 2,340 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.
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 and volume
capacity if available.
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2.0 Emission Estimation
Within the SmartWay Air Tool a fuel-based approach is used for the calculation
of CO2 while an operations-based approach is used for calculating NOx and
PM2.5.
2.1 Emission Calculations Based on Fuel Consumption Data
CO2 emissions are estimated using the following equation:
EM = FUa x FC x EFa
Where:
EM = Emission estimate for CO2 (grams per year)
FUa = Reported fuel use (gallons/year or tons/year) for fuel type a
FC = Fuel conversion factor for gallons to kgs (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)
2.2 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.
2.2.1 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
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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:
EAxp = LTOx x EFlxp
Where:
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)
EFlxp = LTO emission factor for specific aircraft (x) and pollutant (p)
(grams/LTO)
X = Specific aircraft make/model/engine combination
P = Pollutant (NOx or PM2.5)
Additional information on the emission factors used for the LTO emission
calculations can be found in the AirTool-Aircraft-Engine-Data.xIsx file.
2.2.2 Cruising Operations
Reported aircraft hours of operation include time spent in airport-related activities
as well as cruising. For this reason it is necessary to adjust the total hours value
to estimate the time spent in the cruising mode. As noted, the period of time an
aircraft spends in an LTO cycle varies by aircraft make and model, and time-in-
mode values are included in the AEDT model for all modes except idling. The
EPA default value used in the latest National Emission Inventory (NEI) for the
idling time-in-mode is used in the Air Tool.
The time spent in the cruising mode is estimated using the following equation:
TOx = THx - (LTOx x LMx / 60)
Where:
TOx = Total cruising hours of operation for specific aircraft x (hours/year)
THx = Total hours of operation for specific aircraft (x)
LTOx = Annual LTOs for specific aircraft (x)
LMx = Total time spent per LTO cycle, minutes (from AEDT, EPA)
60 = Conversion - minutes per hour
x = Aircraft make and model
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To estimate cruising emissions, the cruising hours of operation are applied to the
cruising emission factors. These emission factors assume that aircraft in cruising
mode operate at the fraction of power specified in the Engine Load % field.
Cruising emissions are estimated using the following equation:
ECxp = TOx x (EFcXpX 3,600) x LFx/70
Where:

ECxp =
Cruising aircraft emissions for specific aircraft model (x) and

pollutant (p) (grams per year)
H
O
X
II
Total cruising hours of operation for specific aircraft x

(hours/year)
EFcxp =
Cruising emission factor for specific aircraft (x) and pollutant (p)

(grams / second)
3,600 =
Conversion seconds per hour
LFx =
Load factor specified for each aircraft make/model (x), in

percent
70
Default engine load factor percent for cruising operations from

AEDT
x =
Specific aircraft make and model
P
Pollutant
Additional information on the emission factors used for the cruising mode can be
found in the AirTool-Aircraft-Engine-Data.xIsx file.
Once LTO and cruising emissions are calculated they are summed to determine
total emissions for each aircraft.
2.3 Aircraft Upload Function
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, and volume capacity values (in cubic feet) are weighted by miles.
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. Users can
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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
	volume capacity
	utilized volume
The first two 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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3.0 Performance Metrics
The SmartWay Air Tool is designed to apply calculated emissions to a variety of
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.
3.1 Grams of Pollutant per Mile
PMP = Y. EMpo / M
Where:
PMp = Grams of pollutant per mile (grams/mile)
EMpo = Total annual emissions summed by pollutant (P) for both
operation types (0) (grams per year)
M = Total annual statute miles flown
P = Pollutant
0 = Operation types (airport and cruising)
3.2 Grams of Pollutant per Ton-Mile
PTMp = X Epto / TM
Where:
PTMp =
Grams of pollutant per ton-mile (grams / ton-mile)
Epo =
Annual emissions summed over operation type (0) by pollutant

(P) (grams/year)
TM =
Total annual ton-miles
P
Pollutant
0
Operations (airport and cruising)
3.3 Grams of Pollutant per Thousand Cubic Foot-Miles
The Air Tool provides aircraft-specific weight and volume capacity in terms of
pounds and cubic feet, respectively. Volume characterization for a given aircraft
make/model includes both passenger and luggage space, as well as the cargo
hold. Capacities were compiled using variety of sources, including manufacturer
websites and the Aviation Source Book. The resulting volume capacity estimates
were quality checked by comparing the ratio of capacity and aircraft length, for
similar type and size aircraft.
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Total mass emissions are divided by total fleet volume capacity and miles
traveled to obtain emissions per thousand cubic foot-miles, using the following
equation:
PCFp = Y. Epo / (CF/1,000 x M)
Where:
PCFp =
Grams of pollutant per aircraft volume (grams/ thousand cubic

foot-miles)
Epo =
Total annual emissions summed over operations (0) by

pollutant (P) (grams/year)
CF =
Total fleet capacity volume (cubic feet)
M
Total annual (statute) miles
P
Pollutant
0
Operations (airport and cruising)
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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, Emission
Dispersion and Modeling System Version 5.1.4.1, August 2013.
U.S. Department of Transportation, Federal Aviation Administration, F-1 and F-2
Forms
U.S. Department of Transportation, Federal Aviation Administration, P-1 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
CO2 emissions are calculated from fuel burn in the SmartWay Air Tool, however
NOx and 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 2c) provides aircraft- and airport-specific fuel
consumption and emissions estimates by operating mode. The operations of
interest for this tool are landing and takeoff operations (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-1.1
Table A-1
Busiest Freight Airports - 2015
Rank
City, State
Airport
Code
Annual
Metric
Tonnes of
Cargo
i
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-1. 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 each.
1 Airports Council International, Airport Traffic Reports, htto ://www.aci-na.orajco ntcnt/airport-1 niITic-
reports.
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The AEDT model and supporting documentation can be found at:
https://aedt.faa.gov/2c information.aspx.
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