U.S. Aviation Greenhouse Gas Emissions Reduction Plan 1
U.S. Aviation Greenhouse Gas Emissions Reduction Plan

Contents

Executive Summary....................................................................................................................................... 4

1 Background ........................................................................................................................................... 8

2 Aircraft and Engine Technology Improvement...................................................................................11

2.1 Program Specifics........................................................................................................................11

2.1.1 FAA Continuous Lower Energy, Emissions and Noise Program..........................................11

2.1.2 NASA....................................................................................................................................13

2.1.3 Department of Defense ......................................................................................................15

2.2 Time Frame and Targets .............................................................................................................16

2.3 Expected Emissions Impacts.......................................................................................................17

2.4 Success Highlights.......................................................................................................................17

2.4.1 FAA CLEEN...........................................................................................................................17

2.4.2 NASA....................................................................................................................................18

2.4.3 Department of Defense ......................................................................................................19

3 Operational Improvements.................................................................................................................20

3.1 Program Specifics........................................................................................................................20

3.1.1 NextGen ..............................................................................................................................20

3.1.2 NASA....................................................................................................................................21

3.2 Time Frame and Targets .............................................................................................................22

3.3 Expected Emissions Impacts.......................................................................................................23

3.4 Success Highlights.......................................................................................................................24

3.4.1 Time Based Flow Management...........................................................................................24

3.4.2 Improved Multiple Runway Operations..............................................................................26

3.4.3 Performance Based Navigation...........................................................................................26

3.4.4 Separation Management ....................................................................................................26

4 Alternative Jet Fuels Development and Deployment.........................................................................28

4.1 Program Specifics........................................................................................................................28

4.2 Time Frame and Targets .............................................................................................................29

4.3 Expected Emissions Impact.........................................................................................................30

4.4 Success Highlights.......................................................................................................................31

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U.S. Aviation Greenhouse Gas Emissions Reduction Plan

5 Policies, Standards, and Measures .....................................................................................................33

5.1 CO2 Standard...............................................................................................................................33

5.2 Global Market-Based Measure ...................................................................................................34

5.3 NextGen Environmental Management System ..........................................................................34

6 Scientific Understanding and Modeling/Analysis...............................................................................35

6.1 Analysis Background ...................................................................................................................36

6.1.1 Forecasting..........................................................................................................................36

6.1.2 Environmental Modeling ....................................................................................................37

6.1.3 System Improvement Assumptions....................................................................................38

6.2 Analysis Results...........................................................................................................................39

7 Summary .............................................................................................................................................42

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U.S. Aviation Greenhouse Gas Emissions Reduction Plan

Executive Summary

This action plan provides an overview of the primary initiatives the United States Government 

(USG)–in partnership with the U.S. aviation industry—is undertaking to reduce greenhouse gas

(GHG) emissions from U.S. aviation. The USG is committed to managing the carbon footprint of 

U.S. aviation while simultaneously enhancing the safety and efficiency of the National Airspace 

System (NAS). This commitment to reducing environmental impacts is reflected in an 

aspirational goal of achieving carbon-neutral growth for U.S. commercial aviation by 2020, 

using 2005 emissions as a baseline. Under the auspices of the Next Generation Air 

Transportation System (NextGen), the USG has laid out plans and initiatives for improvements 

in technology and operations; advances in development and deployment of sustainable 

alternative jet fuels; and policies, standards, and selective measures to incentivize transition of 

the fleet and airspace system. This action plan details the specific programs being pursued 

under these areas, their expected emissions impacts, and notable achievements thus far. The 

USG has prepared this plan as an update to the 2012 United States Aviation Greenhouse Gas 

Emissions Reduction Plan. This plan includes both domestic and international aviation. The 

domestic reductions are reflected in the national contributions submitted by the U.S. to the 

United Nations Framework Convention on Climate Change (UNFCCC). This plan also discusses 

ongoing work to better understand and model the environmental impacts of aircraft, including 

climate impacts, and presents an analysis that projects the future environmental performance 

of the NAS and shows the potential for significant environmental benefit from the aviation 

system improvements that are described in the document. Below are some of the key elements 

of this action plan. 

Aircraft and Engine Technology Improvement

The Continuous Lower Energy, Emissions, and Noise (CLEEN) program, launched by the FAA in

2010, is a collaborative partnership with industry to accelerate development and deployment of

environmentally promising aircraft technologies and sustainable alternative jet fuels. 

Technologies matured under the CLEEN program are anticipated to begin entering the

commercial fleet in 2016. CLEEN II, a follow-on program to CLEEN, will solicit new technology 

concepts expected to be on a path for introduction into commercial aircraft before 2026.

The National Aeronautics and Space Administration (NASA) and the U.S. Air Force continue to 

push research and exploration of environmentally sustainable aviation technologies. NASA does 

this primarily through its Environmentally Responsible Aviation (ERA) and Advanced Air 

Transport Technology (AATT) projects, which focus on new vehicle technologies that have the 

potential to significantly reduce aviation’s impact on the environment. The U.S. Air Force, 

meanwhile, conducts research and testing into vehicle efficiency improvements (e.g., through 

the Adaptive Engine Technology Development program) that can often transition into 

development of commercial products that are utilized by the civil fleet. 

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U.S. Aviation Greenhouse Gas Emissions Reduction Plan

Operational Improvements

Implementation of NextGen will allow for more efficient aircraft operations and reduced GHG 

emissions through operational improvements. Many foundational and infrastructure elements 

are expected to be in place in the near-term, providing critical NextGen capabilities or 

infrastructure upon which future NextGen capabilities will be built. In coordination with the 

aviation industry, the FAA has established key priorities and developed an implementation plan 

to deliver high priority, high readiness capabilities in four focus areas: Multiple Runway 

Operations, Performance Based Navigation (PBN), Surface Operations, and Data 

Communications (Data Comm). The FAA has already introduced a large number of PBN 

procedures into the NAS through the Metroplex program. The NASA Airspace Operations and 

Safety Program supports NextGen through the development and demonstration of integrated 

Air Traffic Management technologies. These programs, among others, have provided and will 

continue to provide operational benefits to the NAS resulting in reductions in fuel burn and 

emissions.

Alternative Jet Fuels Development and Deployment

The USG is actively supporting and facilitating the development and deployment of sustainable 

alternative jet fuels with lower life-cycle GHG emissions than conventional petroleum fuel. 

Interagency coordination and industry collaboration is central to the USG work in this area. The 

Farm to Fly 2.0 cooperation agreement and the Commercial Aviation Alternative Fuels

Initiative (CAAFI) are two primary examples—the former focuses on supply chain and 

production infrastructure creation; the latter, on research and development, environmental

assessment, fuel testing, demonstration, and commercialization. Thus far, the standard setting 

organization ASTM International has approved three alternative jet fuels for use in aviation. 

Research is ongoing to pursue additional approvals and also to examine the viability of regional 

supply chains and chart a path for overcoming barriers to production. These joint initiatives are 

paving the way to large-scale production and broad commercial use of alternative jet fuels, 

thereby providing greater opportunity to meet U.S. environmental goals.

Policies, Standards, and Measures

The USG is pursuing the development of policies, standards, and measures that would 

supplement efforts in technology, operations, and alternative jet fuels to further reduce 

aviation emissions. The USG is focused on two items, in particular: (1) the development of a 

meaningful CO2 standard in ICAO for implementation in the U.S., and (2) working with ICAO on 

the development of a proposal for a Global Market-Based Measure (GMBM) to serve as a gap 

filler to address international aviation GHG emissions. The USG is actively engaged, 

participating, and providing resources towards the successful development and implementation 

of these policy elements.

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U.S. Aviation Greenhouse Gas Emissions Reduction Plan

Scientific Understanding and Modeling/Analysis

The FAA is continually improving its modeling and analysis tools in order to better understand 

and assess the environmental impacts of aviation. One analysis conducted by the FAA explores 

how system improvements (e.g., operational changes, technology improvements, alternative 

jet fuel usage) will help propel the FAA towards environment and energy goals. The below 

figures present projections of CO2 emissions along with potential reductions given moderate 

and aggressive assumptions for technology evolution and alternative jet fuel availability. The 

analysis indicates that significant progress can be made toward the USG’s aspirational climate 

goals through aviation system improvements. Challenges remain to the development and 

deployment of the operational improvements, technology improvements, and alternative fuel 

quantities reflected in these scenarios, and it will take concerted USG and aviation industry 

efforts to work through these challenges in pursuit of environment and energy goals. As the 

underlying tools and assumptions are improved, this analysis will be refined and updated.

Figure ES-1 Projected life-cycle CO2 emissions impacts – moderate system improvement 

scenario1

Life-Cycle 

CO2

Emissions

(as percent 

of 2005 

level)

6 

 

1 Note that combustion/tailpipe emissions are those created by the airline industry, while feedstock production, transportation, and fuel production 

emissions for conventional jet fuel are created by the petroleum extraction and refining industries. The emissions from alternative jet fuels would 

result in a net reduction in the CO2 emissions from fuel production and use. The scenario does not imply that the upstream emissions are 

attributable to airlines, rather than to jet fuel producers and others in the supply chain.
U.S. Aviation Greenhouse Gas Emissions Reduction Plan

Figure ES-2 Projected life-cycle CO2 emissions impacts – aggressive system improvement 

scenario

Life-Cycle 

CO2

Emissions

(as percent 

of 2005 

level)

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U.S. Aviation Greenhouse Gas Emissions Reduction Plan

1 Background

8 

 

The United States Government (USG) is committed to addressing the climate change impacts of 

domestic and international commercial aviation, and is pursuing a multi-pronged approach to 

achieve greenhouse gas (GHG) emissions reductions. In support of these efforts, the U.S. 

Federal Aviation Administration’s (FAA) Office of Energy and Environment (AEE) works 

collaboratively with the International Civil Aviation Organization (ICAO) as well as its Committee 

on Aviation Environmental Protection (CAEP) to address aviation’s impact on the environment. 

The FAA supports the policy work of ICAO and the technical work conducted in CAEP in 

partnership with the Department of State, Environmental Protection Agency and other federal 

agencies.

In October 2010, the 37th ICAO Assembly adopted a comprehensive climate change resolution 

committing to reducing GHG emissions from international aviation. A central element of 

Resolution A37-19 was for States to voluntarily prepare and submit action plans for reducing 

international GHG emissions to ICAO. In response to this request, the USG released the United 

States Aviation Greenhouse Gas Emissions Reduction Plan2 in June 2012 to communicate U.S. 

2 United States Aviation Greenhouse Gas Emissions Reduction Plan (2012) available at 

http://www.faa.gov/about/office_org/headquarters_offices/apl/environ_policy_guidance/policy/media/Aviation_Greenhouse_Gas_Emissions_Re

duction_Plan.pdf
U.S. Aviation Greenhouse Gas Emissions Reduction Plan

aviation plans and initiatives on climate change and to help ICAO track progress towards 

reaching global goals. The 38th ICAO Assembly’s climate change resolution (A38-18)—adopted 

in October 2013—further encourages States to submit action plans to ICAO. The USG has 

prepared this GHG emissions reduction plan as an update to the 2012 document. This plan

includes both domestic and international aviation. The domestic reductions are reflected in the 

national contributions submitted by the U.S. to the United Nations Framework Convention on 

Climate Change (UNFCCC). This plan and U.S. involvement in ICAO’s work also reflect U.S. 

domestic priorities as outlined by The President’s Climate Action Plan3

, released in June of 

2013. The President’s Climate Action Plan highlights the need to develop and deploy advanced 

transportation technologies in response to climate change and emphasizes the importance of 

forging global solutions to climate change through continual dialogue and cooperation between 

nations. 

The FAA, in its Aviation Environmental and Energy Policy Statement4

, has set an 

aspirational goal of achieving carbon-neutral growth for U.S. commercial aviation by 

2020, using 2005 emissions as a baseline. The USG has already made progress in

reducing GHG emissions within the aviation sector through energy efficiency improvements and 

through public-private partnerships. The USG is on a trajectory to continue that progress in 

coming years. 

Under the auspices of the Next Generation Air Transportation System 

(NextGen), the USG has laid out plans and initiatives for implementing a 

five-pillar strategy to address aviation environmental and energy issues. This plan identifies 

actions and progress toward GHG emissions reductions in each of these areas:

• Aircraft and Engine Technology Improvement

• Air Traffic Management Operational Improvements

• Alternative Jet Fuels Development and Deployment

• Policies, Standards, and Measures

• Scientific Understanding and Modeling/Analysis

The following sections in this plan detail the measures that the USG is pursuing under these 

pillars to reduce aviation GHG emissions, expanding on program specifics, time frame and 

targets, expected emissions impacts, and success highlights. The USG has also undertaken a 

system-level analysis to estimate projected CO2 emissions reductions from technology, 

operations, and alternative jet fuels in order to assess progress toward the carbon-neutral 

3 The President’s Climate Action Plan available at http://www.whitehouse.gov/sites/default/files/image/president27sclimateactionplan.pdf 4 Aviation Environmental and Energy Policy Statement available at 

http://www.faa.gov/about/office_org/headquarters_offices/apl/environ_policy_guidance/policy/media/FAA_EE_Policy_Statement.pdf

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U.S. Aviation Greenhouse Gas Emissions Reduction Plan

growth goal for U.S. commercial aviation and to assess the need for further progress through 

mechanisms such as policies, standards, and measures. The results of this analysis are 

presented in Section 6, Scientific Understanding and Modeling/Analysis. 

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U.S. Aviation Greenhouse Gas Emissions Reduction Plan

2 Aircraft and Engine Technology Improvement

The evolution of modern, more fuel‐efficient airframes and engines has 

produced the most significant aviation emissions reductions historically

and will drive more reductions in the future. The USG is leading a 

number of efforts and collaborating with the aviation industry to

develop and improve technology that results in better fuel efficiency

and reduced emissions. USG actions to improve aircraft and engine

technology are carried out among others by the FAA, the National

Aeronautics and Space Administration (NASA), and the Department of

Defense (DOD) and are coordinated through the National Aeronautics

Research and Development Plan.5

FAA, NASA, and DOD are 

leading a number of 

efforts and collaborating 

with industry to develop 

and improve fuel-efficient, 

emissions-reducing 

technology. 

2.1 Program Specifics

2.1.1 FAA Continuous Lower Energy, Emissions and Noise Program

5 National Aeronautics Research and Development Plan available at http://www.whitehouse.gov/sites/default/files/microsites/ostp/aero-rdplan2010.pdf

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The Continuous Lower Energy, Emissions, and Noise (CLEEN) program, launched by

the FAA in 2010, is a collaborative partnership with five aviation manufacturers

(Boeing, General Electric, Honeywell, Pratt & Whitney, and Rolls-Royce) to develop

technologies that will reduce noise, emissions, and fuel burn; to enable alternative jet fuel

use; and to expedite integration of these technologies into current and future aircraft. CLEEN

is focused on the complete aircraft and includes airframe, propulsion, and aircraft control 

technologies. Over the last five years, the total federal investment in the CLEEN program has 

been more than $117 million. With participating aviation manufacturers exceeding the one-toone cost share requirement, the overall investment in the program has exceeded $250 million. 

Technologies matured under the CLEEN program are anticipated to begin entering the

commercial aircraft fleet in 2016.6 These technologies are described in the following sections.

Boeing

Boeing is developing and demonstrating two aircraft technologies that reduce fuel burn and 

noise. The two technologies being examined by Boeing are an Adaptive Trailing-Edge on the 

aircraft wing and a Ceramic Matrix Composite (CMC) acoustic nozzle at the engine exhaust. The 

Adaptive Trailing-Edge is a technology that deploys miniature flaps to improve wing 

aerodynamic efficiency and decrease noise during approach. The CMC engine nozzle can 

withstand higher temperatures and is made of lighter weight material, thus reducing fuel 

consumption. It also includes acoustic treatments that reduce community noise.

General Electric

General Electric (GE) is developing and demonstrating multiple aircraft technologies that will 

reduce fuel burn, emissions, and noise. The Open Rotor engine, consisting of dual counterrotating propellers driven by a gas turbine, can deliver fuel burn reductions due to the lower 

fan pressure ratio that it can achieve. An advanced engine combustor known as the Twin 

Annular Premixed Swirler (TAPS) II can significantly reduce NOx emissions. GE is also developing 

Flight Management System advances that will enable more efficient aircraft trajectories and 

improved engine monitoring and performance.

Honeywell

Honeywell is developing and demonstrating technologies that will increase engine efficiency 

and reduce engine weight. These technologies include new coatings, an impeller that can 

withstand higher temperatures, advanced low leakage air seals, and improved turbine cooling.

These advances enable the engine to run at higher temperatures in the compression and 

turbine system, thereby increasing cycle thermal efficiency.

6 More information about the CLEEN program available at 

http://www.faa.gov/about/office_org/headquarters_offices/apl/research/aircraft_technology/cleen/

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U.S. Aviation Greenhouse Gas Emissions Reduction Plan

Pratt & Whitney

Pratt & Whitney is developing and demonstrating advanced technologies that will enable an 

ultra-high bypass ratio geared turbofan (GTF) engine. GTF engine technologies will contribute to 

reduced aircraft noise and fuel consumption through increased engine efficiency.

Rolls-Royce

Rolls-Royce is developing and demonstrating two technologies aimed at increasing thermal 

efficiency in the turbine section of the engine: Dual-Wall Turbine Airfoil and CMC Blade Track. 

Dual-wall turbine airfoils are projected to provide 20 percent or more reduction in cooling and 

increased operating temperature capability. The new blade tracks made from CMC material are 

projected to offer more than a 50 percent reduction in engine cooling and weight savings 

compared to a metallic design. These efficiency improvements will lead to reductions in fuel 

consumption.

CLEEN II

The FAA is pursuing a follow-on program to continue maturing and accelerating 

environmentally beneficial aircraft technologies and alternative jet fuels after the conclusion of 

the CLEEN program. This program, CLEEN II, will solicit new aircraft technology concepts that 

are expected to be on a path for introduction into commercial aircraft before 2026. This is an 

entirely new competitive selection and award process, like CLEEN went through in 2010. Similar 

to CLEEN, CLEEN II will be a five year program starting in 2015 and expected to run to 2020 with 

a focus on reducing aircraft fuel burn, noise, and emissions and advancing the development of 

alternative jet fuels.

2.1.2 NASA

The NASA Advanced Air Vehicles Program and Integrated Aviation System Research 

Program both conduct research on new vehicle technologies that will have a 

significant impact on reducing emissions. NASA does not build engines or engine 

components, but rather, NASA programs and research generate advanced technologies and 

knowledge. Typically five to ten years after the conclusion of a NASA program, industry will 

build on NASA’s research results and integrate the associated knowledge into commercial 

products. A sample of some of the research focused on vehicle efficiency improvements and 

emissions reduction is described below. 

Vehicle Efficiency Research

The Environmentally Responsible Aviation (ERA) Project’s goal is to reduce the impact of 

aviation on the environment through the development of vehicle concepts and technologies 

that can simultaneously reduce aircraft fuel burn, noise, and emissions. The project is focused 

on maturing and demonstrating integrated technologies in a relevant environment to 

accelerate the technology transition for use in subsequent transport category aircraft and 

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U.S. Aviation Greenhouse Gas Emissions Reduction Plan

engine programs. The research is conducted through a series of integration technology 

demonstrations that will provide viable solutions to the project’s goals between now and 2025.

One focus area for the NASA ERA Project is developing new laminar flow technologies—i.e., 

technologies that reduce drag through smooth, non-turbulent airflow. The first technology in 

this area is an active flow control (AFC) enhanced vertical tail, which entails sizing the vertical 

stabilizer for conventional operating conditions—thus reducing weight and drag—while still

providing the required performance to meet critical engine out situations during takeoff using 

actuators that blow air across the rudder surfaces. The second technology is the development 

and testing of insect residue accretion protection surface coatings. These coatings will help 

maintain smooth airflow over the wing and reduce drag. The research will advance the 

Technology Readiness Level (TRL) of these two drag reduction technologies for aircraft 

applications to the point where they can be integrated into the next generation of aircraft. 

Another focus area for the ERA Project is the development of new lighter weight structures. 

The purpose of this research is to advance the TRL of advanced composite technology for 

aircraft applications to the point where it can be integrated into the next generation of aircraft. 

This research addresses the need for composite technologies that reduce weight and enable 

reduced drag configurations including high aspect ratio wings and advanced aircraft concepts.

A third area of focus for the ERA Project portfolio is the testing of a wing design equipped with 

adaptive compliant trailing edge technology—i.e., flexible trailing-edge wing flaps. Integration 

of compliant structures in next generation aircraft will reduce weight and drag, contributing to 

a reduction in fuel burn. Flight tests will demonstrate and establish airworthiness for a 

compliant structure used as a large primary control surface in a relevant flight environment and 

accelerate the infusion of this technology.

The NASA Advanced Air Transport Technology (AATT) Project (formerly the Fixed Wing Project) 

explores and develops technologies and concepts to enable revolutionary advances in vehicle 

and propulsion system energy efficiency and environmental compatibility. This portfolio 

includes research in aerodynamic, structural, and propulsion efficiency; noise and emissions

reduction; and integrated system concept exploration.

One research focus area for the AATT Project is the development of aerodynamic and 

structures technologies that enable an increase in the optimal wing aspect ratio by 50-100 

percent—reducing weight and drag—while preserving structural safety and flight control. NASA 

is researching a truss-braced wing, a future generation transport aircraft concept that is 

designed to be aerodynamically efficient by employing a high aspect ratio wing design. 

Additionally, NASA continues to investigate the potential for new configurations to greatly 

improve efficiency. One area of related research conducted by the AATT Project seeks to 

achieve a vehicle-level net system benefit with a distortion-tolerant inlet/fan, boundary-layer 

ingesting (BLI) propulsion system on a representative vehicle. The goal is to capture the 

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U.S. Aviation Greenhouse Gas Emissions Reduction Plan

significant energy efficiency and emissions benefits of vehicle drag reduction from BLI while 

minimizing potential propulsion system losses from a practical BLI application.

Emissions Reduction Research

Under the first phase of the ERA Project, NASA worked with various partners to develop fuel 

flexible combustor concepts capable of reducing landing and takeoff cycle (LTO) nitrogen oxide 

(NOx) by 75 percent relative to the CAEP/6 standard.

7

 After evaluations of multiple concepts, 

both GE and Pratt &Whitney demonstrated the potential of meeting this challenging NOx

reduction goal through high pressure sector rig testing. GE tested an advanced version of a 

lean burn concept with heritage from their Twin-Annular Premixing Swirler (TAPS) combustor. 

Pratt & Whitney tested an axially-controlled stoichiometry concept that exceeded the 

established goals. 

Under the AATT Project, NASA has set a goal of more than 80 percent NOx reduction relative to 

the CAEP/6 standard, but achieved in smaller, higher operating pressure engines. The objective 

of the research is to investigate small engine core scaling, fuel injection, and thermal growth 

management technologies needed for obtaining this challenging goal in advanced engine 

cycles. Alternative jet fuels flexibility is also a key driver as NASA looks into capitalizing on the 

potential of these fuels to reduce particulate matter emissions. 

Currently, NASA is involved in technology development for advanced, small core engines. NASA 

is working on several techniques for active combustion control, including Lean Direct Injection 

(LDI). Lean-burn has an unmatched advantage in terms of particulate matter and NOx reduction 

in the cruise phase. NASA also conducts foundational research to better understand 

combustion physics, including developing and validating physics-based combustion models 

against gaseous-fuel and liquid-fuel experiments. 

2.1.3 Department of Defense

The United States Air Force’s mission is an energy-intensive undertaking. To execute 

a mission of global vigilance, reach, and power, the Air Force focuses on four energy 

priorities: improve resiliency, reduce demand, assure supply, and foster an energy 

aware culture.

The Air Force makes a sizable investment each year in energy. Figure 2-1 below puts this into 

context: the Department of Defense consumes the most fuel within the Federal Government 

and the Air Force consumes roughly half of that use ($9B in 2013). Air Force aviation accounts 

for over 80 percent of that amount.

7 CAEP/6 NOx standard: ICAO, “Aircraft Engine Emissions,” Annex 16, Volume II, Third Edition, July 2008, Amendment 7. Copies of this 

document can be obtained from the ICAO website at http://www.icao.int/.

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U.S. Aviation Greenhouse Gas Emissions Reduction Plan

Figure 2-1 US Air Force energy investment comparison charts

The Air Force targets vehicle efficiency improvements through programs in three primary areas: 

(1) improved aerodynamics, (2) weight reduction, and (3) increased engine efficiency. Surfing 

Aircraft Vortices for Energy ($AVE) formation flight technology decreases fuel consumption 

while in formation by harvesting energy from the leader aircraft’s wingtip vortices. In Air Force 

flight tests, precision flying in the wake of a leading aircraft at an operationally realistic and safe 

distance enabled an 8-10 percent fuel savings for the trailing aircraft. Examples of weight 

reduction include removing redundant or unnecessary equipment, applying precise fueling 

loads, and replacing heavy items, such as publications and technical orders with electronic flight 

bags. Several engine efforts are underway to upgrade existing power plants, while new designs

stemming from the Adaptive Engine Technology Development (AETD) program are scheduled to 

be incorporated in the F-35 fighter fleet engine upgrade in 2023; these upgrades translate to a 

25 percent fuel consumption reduction, potentially saving over 1 billion gallons of fuel by 2040. 

Research and testing performed in these military programs can often transition into 

development of commercial products that are utilized by the civil fleet. For instance, DOD 

research evaluating CMC materials for gas turbine engines has helped accelerate the overall

development of CMC technology for aerospace, thus making it more viable for commercial 

purposes.

2.2 Time Frame and Targets

The FAA CLEEN, NASA ERA Project, NASA AATT Project, and DOD’s AETD program goals are 

complementary in their reduction targets and their timeframes.

• A primary aspirational goal of the CLEEN program is to develop and demonstrate, by

2015, technology that reduces fuel burn by 33 percent relative to current technology 

and reduces LTO NOx by 60 percent relative to the CAEP/6 standard. The technology

would then be available for commercialization.

• CLEEN II’s efficiency goal is to develop and demonstrate certifiable aircraft technology 

that reduces aircraft fuel burn by 40 percent relative to year 2000 best-in-class inservice aircraft, and/or supports the FAA goal to achieve a net reduction in climate 

impact from aviation. The LTO NOx goal is to reduce by 75 percent relative to the

CAEP/6 standard, and/or reduce absolute NOx production over the aircraft’s mission. 

Following a similar model to the CLEEN program, the technology will be matured by 

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2020 to the point where it can be entered into product development for eventual 

deployment into the fleet.

• The NASA ERA Project has a goal to reduce mission fuel burn by 50 percent not later

than 2020 for subsonic passenger and cargo transport aircraft. 

• The NASA AATT Project intends to mature technology associated with emerging aircraft

and engine designs slated for introduction into the fleet beyond 2030 with the goal 

of decreasing fuel burn by 70 percent.

• The DOD AETD program has a goal of a 25 percent improvement in fuel efficiency for

military engines by 2020. Some of the military engine fuel efficiency technologies will 

find their way into the civil fleet.

2.3 Expected Emissions Impacts

The technologies described above are currently being advanced by industry investment as well

as FAA, NASA, and DOD funded research. Continued successful maturation of these 

technologies through public-private partnerships and subsequent commercialization by 

industry could yield significant fuel efficiency improvements on the order of 50 to 70 percent

below current levels.

2.4 Success Highlights

2.4.1 FAA CLEEN

In partnership with industry, CLEEN is already accelerating development of aircraft

technologies that reduce fuel burn. Below are some of the program achievements through 

FY2014. 

Boeing

In August and September 2012, Boeing’s “ecoDemonstrator” flight tests demonstrated 

Adaptive Trailing-Edge technology. Under an agreement with American Airlines, these tests 

used one of the airline’s 737-800 models for flight testing in Glasgow, MT. The Adaptive 

Trailing-Edge technology has the potential for 2 percent fuel burn savings and 1.5 EPNdB 

cumulative noise reduction in single and twin aisle configurations. In spring 2013, Boeing 

completed ground testing of its Ceramic Matrix Composite (CMC) engine nozzle. In July 2014, 

this technology was successfully flight tested on the Boeing 787 “ecoDemonstrator.” The CMC 

nozzle has the potential for 1 percent fuel burn savings—enabling hotter, more efficient 

engines—while allowing for noise reduction treatment and reducing nozzle weight.

GE

In January 2012, GE completed core engine tests of the TAPS II Combustor. Results show LTO 

NOx emissions were reduced 60 percent compared to the ICAO NOx standard adopted in 2004, 

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meeting one of the CLEEN goals. This combustor will be used in CFM International’s LEAP 

turbofan engine and is expected to enter service in 2016. In January 2012, GE completed scaled 

Open Rotor wind tunnel tests. Results indicate aircraft fuel burn on a single aisle aircraft may 

be reduced 26 percent relative to a CFM International, CFM56-7B engine, and cumulative noise 

may be reduced by up to 15 dB relative to FAA Stage 4 (ICAO Chapter 4) noise standards. In 

March 2013, GE demonstrated flight trajectory synchronization between aircraft and the En 

Route Automation Modernization (ERAM) system. Trajectory synchronization will provide pilots 

and controllers better predictability of an aircraft’s location, enabling fuel savings through more 

efficient aircraft routing.

Honeywell

From 2012 through 2014, Honeywell completed engine tests of a number of its CLEEN 

technologies, validating their capability of increased engine temperature and efficiency. 

Honeywell plans to continue engine ground tests of the remaining technologies through 2015.

The Honeywell CLEEN technologies will contribute 5 percent toward an overall 15.7 percent 

reduction in fuel burn resulting from an engine upgrade relative to baseline engine technology.

Pratt & Whitney

In June 2012, Pratt & Whitney began NASA wind tunnel tests of an advanced fan for an ultrahigh bypass ratio geared turbofan engine. Results were used to validate the CLEEN geared 

turbofan engine design. Further wind tunnel tests and an engine ground test of the GTF engine 

are scheduled for 2015 and 2016. This engine is projected to reduce single aisle aircraft fuel 

consumption by 20 percent relative to a CFM International, CFM56-7 engine and reduce noise 

by 25 dB relative to the Stage 4 noise standards. 

Rolls-Royce

In July 2011, Rolls-Royce completed CMC turbine blade tracks (shrouds) component tests. 

Engine testing of this technology began in spring 2013. This technology, along with RollsRoyce’s dual wall turbine vane, is aimed at increasing thermal efficiency in the turbine section 

of the engine. Technology benefits from Rolls-Royce’s work will realize up to a 1 percent 

reduction in fuel consumption.

2.4.2 NASA

Building on work performed during the first phase of the ERA Project, NASA has selected eight 

large-scale integrated technology demonstrations8 to advance ERA research. This phase of the 

research is focused on five areas: aircraft drag reduction through innovative flow control 

concepts; weight reduction from advanced composite materials; fuel and noise reduction from 

advanced engines; emissions reductions from improved engine combustors; and fuel 

8 List of integrated technology demonstrations available at 

http://www.nasa.gov/topics/aeronautics/features/blue_skies_green.html#.VMJhby6fiWs

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consumption and community noise reduction through innovative airframe and engine 

integration designs. These flight and ground technology tests aim to further the project's goals 

of simultaneous reductions in fuel, emissions, and noise from commercial transport planes. As 

an example, in 2014, NASA and the U.S. Air Force Research Laboratory began flight testing of 

the adaptive compliant trailing edge—a technology that will reduce wing structural weight and 

give engineers the ability to aerodynamically tailor the wings to promote improved fuel 

economy and more efficient operations. This and other ERA demonstrations are expected to 

continue through 2015. Under the AATT Project, tests in the NASA Langley Transonic Dynamics 

Tunnel of concepts such as a truss-brace configuration and boundary-layer ingesting propulsion 

systems are validating prior analyses showing the potential of these technologies for fuel burn 

reduction and environmental benefits. 

2.4.3 Department of Defense

Since 2010, the Air Force has consumed over 9 billion gallons of fuel. Table 2-1 below shows a 

decrease each year in fuel consumption. This decrease is due to both a reduction in flying hours 

resulting from a reduction in mission and increased efficiencies from technology and 

operational improvements. Air Mobility Command, the Air Force’s largest fuel consumer, was 

able to achieve gains of 8 percent (with a commensurate avoidance of over 800,000 metric tons 

CO2e) through its efforts in 2013. These reductions are not part of the U.S. action plan; 

however, they do highlight the commitment of the United States to reduce emissions 

associated with aviation fuel use.

Table 2-1 US Air Force fuel consumption per year

Year Fuel GHG Emissions (Jet Fuel only)

FY2010 2.51 billion gal 24.5 MMT CO2e

FY2011 2.45 billion gal 23.9 MMT CO2e

FY2012 2.25 billion gal 22.0 MMT CO2e

FY2013 1.96 billion gal 19.1 MMT CO2e

Note: Calculated using White House CEQ/DOE FEMP FY14 Annual Energy Management Report/Greenhouse Gas 

Reporting Tool, reported in Million Metric Tons CO2 equivalent (MMT CO2e).

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U.S. Aviation Greenhouse Gas Emissions Reduction Plan

3 Operational Improvements

Achieving more efficient aircraft operations is another critical element for reducing GHG 

emissions from aviation. The FAA is implementing a comprehensive, multi-year overhaul of the 

NAS known as NextGen. While the benefits of NextGen are many and go well beyond 

environment, among the key elements of NextGen are reducing delays, establishing more 

precise routes, and improving overall efficiency of the NAS, all of which can contribute to 

reduced fuel burn and emissions.

3.1 Program Specifics

3.1.1 NextGen

Implementation of NextGen will allow for more efficient aircraft 

operations and reduced GHG emissions through operational 

improvements. With NextGen foundational and infrastructure elements 

in place by the end of 2015, benefits are expected to increase 

incrementally as NextGen procedures are implemented and operators 

equip for those procedures. In 2014, the FAA completed the baseline 

ground infrastructure for Automatic Dependent Surveillance-Broadcast 

(ADS-B), the satellite-based successor to radar that provides increased 

Implementation of 

NextGen will allow for 

more efficient aircraft 

operations and reduced 

GHG emissions through 

operational 

improvements. 

20
U.S. Aviation Greenhouse Gas Emissions Reduction Plan

situational awareness and airspace efficiency. En Route Automation Modernization (ERAM) is 

replacing the legacy HOST automation system that the FAA has used to control high-altitude 

airspace since the 1970s. ERAM will increase air traffic flow and improve automated navigation 

and conflict detection services. Under the Terminal Automation Modernization and 

Replacement (TAMR) program, similar upgrades are being made to the automation platform 

used to control low-altitude airspace near airports. These are some of the programs that are 

either providing critical NextGen capabilities or providing the infrastructure upon which critical 

NextGen capabilities will be built. This technological foundation will allow the NAS to operate 

with greater efficiency, increased predictability, and reduced environmental impact. There are a 

variety of implemented and planned operational improvements under NextGen that reduce 

CO2 emissions through mechanisms such as reduced track miles flown and more efficient 

routing. These programs are discussed in later sections.

3.1.2 NASA

The NASA Airspace Operations and Safety Program conducts a broad range of research focused 

on improving the performance and efficiency of the Air Transportation System. This research 

focuses on various phases of operations including surface, terminal, and en route. Results of 

NASA’s research to define and validate the Efficient Descent Advisor (EDA) concept were 

officially transferred in FY2012 to the FAA for further evaluation and potential operational use. 

The EDA concept helps air traffic controllers allow airliners of all sizes to more efficiently 

descend from cruising altitude to arrive at an airport using less engine power while maintaining 

a safe distance from other aircraft. As a result, airlines save money on fuel, fewer emissions are 

released into the atmosphere, and air traffic controller workload is reduced (since automation 

is added to the process). In fact, NASA simulations showed a potential annual savings of $300 

million in fuel. Technology based on NASA’s EDA concept is scheduled to be deployed as part of 

the FAA’s Trajectory Based Flow Management (TBFM) program.

The Airspace Systems Program continued progress towards Air Traffic Management Technology 

Demonstration-1 (ATD-1), which will showcase an integrated set of technologies that provide 

an efficient arrival solution for managing an aircraft’s descent from cruising altitude all the way 

down to the runway. One of the ATD-1 tools, Terminal Sequencing and Spacing (TSS), was 

transferred to the FAA in July 2014. TSS technology provides information to controllers about 

the speeds they should assign to aircraft as they follow more fuel-efficient, continuous-descent 

approaches into airports, saving both time and fuel while reducing emissions. Results 

demonstrate user operational benefits through the integration of ADS-B enabled Flight Deck 

Merging and Spacing; Terminal Area Precision Scheduling; and Controller-Managed Spacing for 

increased throughput and efficiency with a benefit potential of $500M/year if deployed by 

2020.

NASA has conducted human-in-the-loop simulations of advanced trajectory-based algorithms 

that reduce aircraft delays during taxi as part of its Spot and Runway Departure Advisor 

(SARDA) project. Delays on the airport surface are one of the major factors limiting the ability 

21
U.S. Aviation Greenhouse Gas Emissions Reduction Plan

of airports to accommodate high levels of surface traffic throughput. These algorithms include 

a more advanced surface movement planning horizon (up to one hour) leading to reduced 

surface congestion. Benefits studies for several complex U.S. airports show a taxi delay 

reduction of between three to five minutes resulting in annualized fuel savings of $2.5 million 

to $7.5 million at each airport using these algorithms. Technology transition to the FAA may 

occur as early as 2015. 

NASA is collaborating with the FAA to explore the use of NASA’s Precision Departure Release 

Capability (PDRC) that couples advanced airspace flow management and airport surface traffic 

tools. PDRC allows precision scheduling of departing aircraft to allow for smooth integration 

into available slots in the high-altitude overhead streams. Missed departure slots in the 

overhead stream translate to departure delays and lost system capacity. The technology 

automates what is today an inefficient manual process for negotiating a take-off time between 

the control tower and en route control center. As compared to today’s process, NASA expects 

take-off time conformance to double in improvement, representing an estimated $20 million in 

annual system-wide savings. NASA successfully transferred the PDRC technology to the FAA in 

2013. 

Bad weather causes seventy percent of air traffic delays. Until now, airline dispatchers and FAA 

traffic managers did not have a way to continuously reevaluate the pre-departure weather 

avoidance routes for each flight. NASA's Dynamic Weather Rerouting (DWR) tool enables 

dynamic, "real-time" adjustments to flight paths to avoid bad weather with minimum delay

while also saving fuel. The tool integrates trajectory-based automation; convective weather 

modeling that predicts the growth and movement of storms; and algorithms to automatically 

compute minimum-delay routes around bad weather. Researchers and U.S. airlines are 

engaged to conduct field trials to demonstrate its payoffs under real-world air traffic 

management scenarios. Laboratory simulations and field tests of DWR conducted have shown 

potential average savings of 10 minutes or, in operating costs, an estimated $1,700 per flight 

impacted by severe weather.

3.2 Time Frame and Targets

Given the broad scope of NextGen, there is a comprehensive planning and implementation 

process for achieving the full range of NextGen benefits. These implementations are currently 

improving many aspects of the country’s aviation operations with individual elements being 

implemented throughout the next six years. The emissions reductions resulting from NextGen 

are intended to support the overall aspirational goal of carbon-neutral growth by 2020.

In response to a request from the House of Representatives Committee on Transportation and 

Infrastructure, Subcommittee on Aviation, the FAA and aviation industry collaborated through 

the NextGen Advisory Committee (NAC) to establish a set of priorities and develop an 

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U.S. Aviation Greenhouse Gas Emissions Reduction Plan

implementation plan (NextGen Priorities Joint Implementation Plan9) to deliver high priority, 

high readiness capabilities in four focus areas—Multiple Runway Operations, Performance 

Based Navigation (PBN), Surface Operations, and Data Communications (Data Comm)—with the 

FAA committing to specific site implementation plans and industry ensuring operator 

preparedness in order to take full advantage of NextGen benefits. These priorities will provide 

operational benefits to the NAS and increased reductions in fuel burn and emissions. The plan 

summarizes implementation goals with respect to these priorities at specific airports over the 

next three years, and provides a timeline of capability milestones at each of these locations.

Example implementation commitments from this plan include:

• Increased use of wake categorization, improvements for dual and independent parallel 

runway operations, and reduced separation standards between dependent, dual, and triple 

runways at multiple locations nationwide by the close of 2017.

• Improved air traffic flow in the Atlanta, Charlotte and Northern California metroplexes 

using primarily satellite-based navigation and on-board aircraft equipment to navigate 

with greater precision and accuracy—which will provide a variety of benefits to NAS 

users across the country, including shorter and more direct flight paths and improved 

airport arrival rates—by the close of 2017. 

• Improved data sharing with stakeholders, refined departure management capabilities, 

and improved coordination among air traffic control personnel through the use of 

electronic flight strips by the close of 2017. 

• Data Comm departure clearances at 56 airports to provide digital communications 

services between pilots and air traffic controllers and enhanced air traffic control 

information to airline operations centers by the close of 2019.

3.3 Expected Emissions Impacts

Since its inception, NextGen efforts have been designed to have an impact on fuel savings and 

GHG reductions. The FAA has seen improvements in arrival rates, delay times, track miles, and 

taxi times. One of the NextGen priorities that is expected to translate to direct emissions 

reductions is Performance Based Navigation (PBN). The implementation of Area Navigation 

(RNAV) and Required Navigation Performance (RNP) procedures is expected to result in 

reductions in fuel burn and emissions. The FAA is currently introducing a large number of PBN 

procedures into the NAS through the Metroplex program. 

Metroplex is an effort to implement PBN procedures along with changes in airspace design in 

large metropolitan areas that include several commercial and general aviation airports. Due to 

the density of airports and airspace complexity, there are an increased number of 

interdependencies at these locations, resulting in increased delays, inefficiencies, and impacts 

9 NextGen Priorities Joint Implementation Plan available at http://www.faa.gov/nextgen/media/ng_priorities.pdf

23

 
U.S. Aviation Greenhouse Gas Emissions Reduction Plan

to the environment. The implementation of PBN at these metroplexes is expected to achieve 

significant savings in fuel burn and carbon emissions. Figure 3-1 on the following page 

illustrates each of the metroplexes along with estimates of expected fuel and carbon savings.

3.4 Success Highlights

NextGen initiatives have resulted in many success stories that have contributed to the FAA’s 

emissions reduction goals. The FAA estimates that since 2010, NextGen improvements have 

saved 59 million gallons of fuel and reduced CO2 emissions by 565 thousand tons, with 170 

thousand tons of CO2 saved in 2014 alone. 

Table 3-1 highlights some examples of recent implementations that are contributing to the 

achievement of fuel burn and CO2 emissions savings.

Table 3-1 Completed NextGen improvements with significant fuel and CO2 savings

Portfolio Implementation Operational Benefit Environmental Benefits in 2014

Time Based Flow 

Management

NAS-wide deployment of 

Traffic Management 

Advisor with Adjacent 

Center Metering 

Improved aircraft spacing 

reduces vectoring and 

holding prior to arrival

 Saved 3.7 million gallons of fuel 

 Reduced CO2 emissions by 35 

thousand metric tons

Improved Multiple 

Runway Operations

Dependent approaches at 

San Francisco

New 7110.308 procedure 

allows for increased airport 

throughput during poor 

visibility conditions

 Saved 3.6 million gallons of fuel

 Reduced CO2 emissions by 34 

thousand metric tons

Performance Based 

Navigation

Transition to PBN Q-routes 

for cruise operations

New PBN Q-routes add 

predictability and reduce 

excess time en route

 Saved 6.5 million gallons of fuel

 Reduced CO2 emissions by 62

thousand metric tons

Equivalent Lateral Spacing 

Operations (ELSO) 

implemented in Atlanta

New PBN procedures 

allow for additional 

departure routes, 

increasing throughput and 

reducing taxi time

 Saved 1.7 million gallons of fuel

 Reduced CO2 emissions by 16

thousand metric tons

Separation 

Management

Re-categorization of wake 

separation standards 

(Wake RECAT) at various 

airports

Improved wake separation 

standards have increased 

departure throughput, 

reducing time spent 

waiting on the taxiway

 Saved 1.4 million gallons of fuel

 Reduced CO2 emissions by 13

thousand metric tons

3.4.1 Time Based Flow Management

Time Based Flow Management (TBFM) uses time instead of distance to help controllers 

separate air traffic. It provides more efficient traffic flow compared to the traditional miles-in24
U.S. Aviation Greenhouse Gas Emissions Reduction Plan 25

Figure 3-1 Projected fuel and carbon savings at U.S. metroplexes10

10 Savings estimates are annual benefits expected to accrue upon completion of NextGen near-term procedural improvements implemented under the FAA's Metroplex program. They are based on the 

FAA's preliminary assessment of proposed airspace improvements compared to operations in a year before any improvements were made. More information available at 

https://www.faa.gov/nextgen/snapshots/metroplexes/

 
U.S. Aviation Greenhouse Gas Emissions Reduction Plan 26

trail traffic flow management. TBFM uses the capabilities of the Traffic Management Advisor 

(TMA), a system already deployed to all en route centers. 

Improvements in TMA's trajectory modeler and Time Based Metering (regulating traffic flow by 

directing aircraft to be at a specific point in space at a specific time) optimize airspace capacity. 

In particular, facilities using the new Arrival Metering capability were able to save 8 to 10 

minutes per metered flight (or an average of nearly 2 minutes across all flights), resulting in 

benefits to flight operators and passengers of $200 million per year.

3.4.2 Improved Multiple Runway Operations

In November 2008, the FAA published Order 7110.308, allowing dependent instrument 

approaches to certain parallel runways with centerline spacing of less than 2,500 feet, known as 

Closely Spaced Parallel Runways (CSPR). After a thorough safety review and air traffic 

controller training, San Francisco International Airport (SFO) was added to the list of authorized 

airports in October of 2012.

The new dual runway approaches at SFO have increased throughput during instrument 

meteorological conditions (IMC) when only single-runway approaches were possible in the past. 

The resulting throughput gain has reduced average departure delays by 2.7 minutes and arrival 

delays by 5 minutes, saving over 3 million gallons of fuel per year.

3.4.3 Performance Based Navigation

Q-Routes are published high altitude routes available for use by RNAV-equipped aircraft. They 

are designed to alleviate airspace complexity in corridors with high traffic volume, and to 

enhance the predictability of traffic flows in these corridors. By comparing data on flights 

between the same city pairs, the FAA determined that flights requesting Q-routes flew an 

average of 14 miles less and experienced an average of 2 minutes less delay than flights using 

conventional jet routes. This equates to a total savings of 6.5 million gallons of fuel per year, 

which in turn reduces carbon dioxide emissions by 62 thousand tons. 

A different application of PBN is found in the Equivalent Lateral Spacing Operations (ELSO) 

program that was implemented at Hartsfield-Jackson Atlanta International Airport (ATL), which 

reduces departure route angles from 15 to 10 degrees without sacrificing aircraft separation. 

These additional departure routes have increased throughput at the airport, resulting in taxi 

times that are over 2 minutes shorter per flight. This results in a reduction in fuel burn on the 

ground of over 1.7 million gallons per year.

3.4.4 Separation Management

Using various navigation equipment and wake performance capabilities, standards and 

procedures have been created allowing aircraft separation in the NAS to be both enhanced and 

assured. Using modern data and analytical techniques, new wake turbulence categories have 

been created in multiple phases of Wake Re-Categorization (Wake RECAT). Memphis

International Airport and Louisville International Airport were the first of many airports to 
U.S. Aviation Greenhouse Gas Emissions Reduction Plan

benefit from this effort to reduce the separation of aircraft. Wake RECAT at these two airports 

has resulted in fuel savings from reduced taxi times of 1.3 million gallons per year, with further 

savings anticipated as ATL also comes on line. 

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U.S. Aviation Greenhouse Gas Emissions Reduction Plan

4 Alternative Jet Fuels Development and Deployment

The USG is actively supporting and facilitating the development and deployment of sustainable 

alternative jet fuels with lower life-cycle GHG emissions than conventional petroleum fuel. 

4.1 Program Specifics

The USG has taken significant steps since 2006 to facilitate the development and 

deployment of “drop‐in” alternative jet fuels. “Drop‐in” jet fuel can be used without changesto 

aircraft systems or fueling infrastructure; it may also reduce aircraft emissions and enhance

U.S. energy security. 

The Commercial Aviation Alternative Fuels Initiative (CAAFI)—a public-private

partnership between the USG, airlines, aircraft manufacturers, airports, and fuel 

producers—has led efforts in research and development; environmental

assessment; fuel testing; and demonstration and commercialization of alternative aviation

fuels. CAAFI efforts contributed to the creation of testing protocols and new alternative

fuel specifications that have enabled approvals for aviation to use new fuels in commercial

service. This is paving the way to large-scale production and use of these fuels. This 

leadership has also helped make aviation a major target market for the alternative fuels sector.

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U.S. Aviation Greenhouse Gas Emissions Reduction Plan

The USG is taking a multidisciplinary and multi-agency approach to 

support development and deployment of alternative jet fuels. The U.S. 

Departments of Agriculture (USDA), Commerce (DOC), Energy (DOE), 

Defense (DOD), the Environmental Protection Agency (EPA), the FAA, 

NASA, and the National Science Foundation (NSF) have all made 

investments to support alternative jet fuel research, development, and 

production. Aviation is a key strategic target, partner, and market for 

accomplishing USG goals of promoting bioenergy production, enhancing sustainability and 

supporting economic development and innovation. 

The USDA is particularly focused on crop and investment programs to support aviation fuel 

production. The DOE is focusing research funding on the development of new and more 

efficient biomass conversion technologies to produce alternative jet fuel. The USDA, DOE, and 

the FAA have jointly signed a Farm to Fly 2.0 cooperation agreement alongside the commercial 

and business aviation community to focus efforts on enabling the creation of a supply chain and 

production infrastructure to support a goal of one billion gallons of alternative jet fuel to be 

used by U.S. aviation by 2018. 

In a complementary effort, the President directed the U.S. Navy, DOE, and USDA to make 

investments in the construction and operation of three biorefineries that will produce up to 100 

million gallons of cost competitive alternative diesel and jet fuel beginning in 2016. The FAA 

and DOD are working together with industry to coordinate and fund alternative jet fuel testing 

activities that support fuel approval. NASA, the FAA and the U.S. Air Force are leading efforts to 

understand the benefits of alternative jet fuels on emissions that impact air quality and contrail 

formation. 

The DOE has also become a key government contributor to aviation alternative fuels efforts 

with research & development, fuel testing, and fuel production investments. The U.S. 

Renewable Fuel Standard (RFS) mandates the use of 36 billion gallons of renewable fuels by

2022, but does not mandate jet fuel production. However, the EPA has ensured that alternative 

jet fuels can receive credit toward the volume requirement, thereby enhancing the potential 

commercial value of the qualified fuels and creating further incentive for production. 

The USG is taking a 

multidisciplinary and 

multi-agency approach to 

support alternative jet fuel 

research, development, 

and production.

4.2 Time Frame and Targets

The FAA has set an aspirational goal for U.S. aviation to use one

billion gallons of alternative jet fuel per year by 2018, displacing one

billion gallons of petroleum jet fuel. The U.S. Air Force has a goal of 

being ready to cost-competitively acquire 50 percent of its domestic 

aviation fuel from domestically sourced 50/50 alternative fuel blends 

by 2016.11 The U.S. Navy has a goal to have 50 percent of the naval 

The FAA has set an 

aspirational goal for U.S. 

aviation to use one billion 

gallons of alternative jet 

fuel per year by 2018, 

displacing one billion 

gallons of petroleum jet 

fuel.

11 More information available at http://www.safie.hq.af.mil/shared/media/document/AFD-091208-027.pdf

29

 
U.S. Aviation Greenhouse Gas Emissions Reduction Plan

fleet’s total energy consumption from cost competitive alternative sources by 2020.12 It is a 

legal requirement that alternative fuels purchased by the USG be produced in a manner that 

has a lower GHG footprint than conventional petroleum-based fuels.13 The Farm to Fly 2.0 

agreement has been signed by the FAA, USDA, DOE, and the aviation industry. It formalizes the 

intent of the parties to “work together to enable commercially viable, sustainable bio-Jet Fuel 

supply chains in the U.S. that are able to support the goal of one billion gallons of bio-Jet Fuel 

production capacity and use for the Aviation Enterprise by 2018.”

In general, for an alternative jet fuel to be broadly used by commercial aviation, it needs

to be approved by the widely recognized industry standards setting organization ASTM

International. To date, ASTM has approved three alternative jet fuels that use vegetable and

waste oils, fats, and greases; sugars; and lignocellulosic biomass as raw materials. The approval

of additional alternative jet fuels is being pursued to ensure that an even wider range of

feedstock and fuel producers have access to the jet fuel market, increasing the chances of 

reducing cost and providing greater opportunity to meet U.S. environmental goals. In 2014, the

FAA worked with industry and with the Brazilian government to facilitate ASTM approval of 

sugar-derived alternative jet fuel.

The FAA, DOD, and NASA continue to collaborate with industry to advance additional fuel 

pathways that could more cost effectively convert materials to alternative jet fuels. Once 

sufficient testing is completed, ASTM is expected to consider approval of the next fuel types, in 

2015 and 2016. These fuel pathways could use a wide range of feedstocks, including alcohols, 

which are then upgraded to jet fuel. A half dozen fuel pathways are also under development 

and testing and being considered for approval. The USG will continue to examine feedstocks 

that could be used to create jet fuel, focusing on those that have a minimal impact on land use, 

fresh water supply, and food crops. 

4.3 Expected Emissions Impact

The fuel production pathways approved for use to date provide a range of possible life-cycle 

GHG benefits. Alternative fuel analyses conducted by the PARTNER Center of Excellence have

shown reductions of up to 80 percent life-cycle GHG emissions for some renewable alternative 

jet fuel pathways such as sugar-based Synthesized Iso-paraffins (SIP) or fuel from lignocellulose 

via the Fischer-Tropsch (FT) process. Many oil-based Hydroprocessed Esters and Fatty Acids 

(HEFA) pathways show approximately a 50 percent reduction in GHG emissions.

14

For the U.S. RFS, the EPA has also evaluated the lifecycle greenhouse gas emissions associated 

with a number of jet fuel pathways produced from renewable biomass.15 The agency’s 

assessments, which determine the legal eligibility of different fuel pathways for tradable credits 

12 More information available at http://greenfleet.dodlive.mil/files/2010/10/Navy-Energy-Vision-Oct-2010.pdf 13 “Energy Independence and Security Act of 2007”, Section 526, One Hundred Tenth Congress of the United States of America, 2007. 14 Stratton RW, Wong HM, Hileman JI (2010) Life Cycle Greenhouse Gas Emissions from Alternative Jet Fuel, Version 1.2. Cambridge, 

Massachusetts: PARTNER/MIT 15 For the list of existing fuel RFS pathways see: http://www.epa.gov/otaq/fuels/renewablefuels/new-pathways/approved-pathways.htm 

30

 
U.S. Aviation Greenhouse Gas Emissions Reduction Plan

under the RFS program, have found that HEFA jet fuels produced from soybean oil, oil from 

annual cover crops, algal oil, biogenic waste oils/fats/greases, non-food grade corn oil, or 

camelina sativa oil reduce lifecycle GHG emissions by at least 50% compared to a 2005 

petroleum baseline. The EPA also determined that jet fuel produced from a number of 

cellulosic feedstocks achieves a 60% GHG reduction compared to the same baseline.

These fuels also demonstrate potentially significant reductions in SOx and particulate matter 

(PM) emissions that impact air quality and contrail formation. NASA continues efforts in 

characterizing the emissions of alternative fuels through both ground and flight testing. 

Recently, NASA completed the second Alternative Fuel Effects on Contrails and Cruise 

EmiSSions (ACCESS) flight campaign. During this flight campaign, NASA, along with 

international partners the German Aerospace Center (DLR) and National Research Council of 

Canada (NRC), gathered critical data that helps to quantify the effects of these fuels on the 

environment and may aid in the development of cleaner aircraft fuels of the future. 

4.4 Success Highlights

The following are several examples of progress and successes in the development of 

sustainable alternative fuels for aviation.

• In April 2013, the USDA and the FAA joined with industry partners from Airlines for 

America (A4A), Aerospace Industries Association (AIA), Airports Council-North America 

(ACI-NA), National Business Aviation Association (NBAA) and the General Aviation 

Manufacturers Association (GAMA) in an expanded “Farm to Fly 2.0” collaboration “to 

enable commercially viable, sustainable bio-Jet Fuel supply chains in the U.S. that are 

able to support the goal of one billion gallons of bio-Jet Fuel production capacity and 

use for the Aviation Enterprise by 2018.” In July 2014, the DOE also signed on as a 

partner to the agreement. A recent concrete outcome is the application of the feedstock 

readiness measurement tool to a large number of feedstocks to inform the Farm to Fly 

working group about availability and feasibility of the key raw materials for alternative 

fuel production.

• In September 2013, the FAA established the Aviation Sustainability Center (ASCENT), a 

Center of Excellence for Alternative Jet Fuel and Environment. ASCENT continues the 

tradition of university research started by PARTNER with an expanded focus on 

alternative jet fuels. ASCENT has had considerable congressional interest. Within the 

FY2014 budget, the FAA will fund ASCENT at a $10M level. ASCENT Project number 1 

focuses on examining the potential of regional supply chains within the United States to 

meet U.S. goals for alternative jet fuel production and chart a path for accomplishing 

this production. 

• In June 2014, the standard-setting organization ASTM International approved a third 

alternative jet fuel known as Synthesized Iso-Paraffins for commercial use up to a 10 

percent blend level. This approval follows previous approvals for FT and HEFA fuels. It 

31
U.S. Aviation Greenhouse Gas Emissions Reduction Plan

enables the use of alternative fuels produced from plant sugars and provides an 

estimated 80 percent reduction in life-cycle GHG emissions. The FAA’s CLEEN Program 

supported key testing that enabled the approval of SIP. Additional fuels are currently 

undergoing testing and evaluation with FAA support for future approval by ASTM 

International. 

• U.S. commercial airlines have announced agreements for purchase of sustainable 

alternative jet fuels. United Airlines will take delivery of 5 million gallons per year of 

HEFA fuel from waste oils from Altair Fuels for use at Los Angeles International Airport 

beginning in 2015. Southwest Airlines has announced plans to purchase 3 million gallons 

per year for San Francisco, CA airports from Red Rock Biofuels beginning in 2016. 

Additional commercial announcements are anticipated.

• In September 2014, the USDA, DOE, and the U.S. Navy announced awards to support 

construction of three production facilities to produce “drop-in” aviation and marine 

biofuels to power military and commercial transportation. The three agencies are 

investing up to $510 million over three years. The DOE and DOD are utilizing the 

Defense Production Act Title III, which allows the U.S. to invest in strategically significant 

industries. The USDA plans to provide its contribution through the use of its Commodity 

Credit Corporation. Beginning in 2016, the three facilities are expected to produce as 

much as 100 million gallons of fuel per year at an average cost of $3.50 per gallon. 

• The DOE Bioenergy Technology Office (BETO) supports development of pilot- and 

demonstration-scale fuel production facilities that produce fuel to replace the entire 

barrel of oil, including jet fuel. DOE is planning additional funding of alternative jet fuel 

development.

• The USG has established formal bilateral cooperation agreements with Australia, Brazil, 

Germany, and Spain, each of which have strong alternative jet fuel initiatives. The FAA 

also supports and participates in ICAO‘s activities on alternative jet fuels including the

CAEP Alternative Fuels Task Force.

• The USG is working together with industry to develop a National Alternative Jet Fuels 

Research and Development Strategy. This strategy is planned to be released by the 

Committee of Technology under the National Science and Technology Council. It is 

intended to mobilize the stakeholder community and enhance national research and 

development coordination in support of alternative jet fuel development and 

deployment. 

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U.S. Aviation Greenhouse Gas Emissions Reduction Plan

5 Policies, Standards, and Measures

The USG is actively pursuing the development of policies, standards, and measures that would 

supplement efforts in technology, operations, and alternative jet fuels to further reduce 

aviation emissions.

5.1 CO2 Standard

The USG is committed to the development of a meaningful CO2 standard in ICAO for 

implementation in the U.S. under the Clean Air Act. In this regard, ICAO/CAEP is currently 

working toward adopting a meaningful CO2 standard for aircraft with support from the USG and 

industry and environmental stakeholders. The primary aim of the CO2 standard is to incentivize 

faster development of technology and serve as a basis for ensuring that less efficient aircraft 

and engine technologies are eliminated over time.

In support of the international aircraft CO2 standard development, the USG has contributed to 

the work during all phases, including the development of the aircraft CO2 metric measurement 

system and potential regulatory levels, all of which were aimed to be economically reasonable, 

environmentally beneficial and take into account interdependencies with other standards. 

Currently, the USG plays a critical role in taking the work further by conducting the analysis of 

the costs of possible CO2 standard regulatory levels. This analysis takes into account feasible 

33
U.S. Aviation Greenhouse Gas Emissions Reduction Plan

CO2-improving technologies that aircraft could adopt in order to meet the potential CO2

regulatory levels under consideration. Efforts by the USG are also underway to support the 

completion of the international certification requirement for the standard, which will ultimately 

be promulgated as domestic rules. Domestically, the EPA is moving forward with a rulemaking 

process that may result in findings regarding aircraft GHG emissions. The EPA plans to issue an 

Advanced Notice of Proposed Rulemaking (ANPRM) to provide an overview of ICAO/CAEP 

efforts in establishing a global aircraft CO2 standard and the potential use of the Clean Air Act to 

implement a corresponding aircraft CO2 emissions standard domestically. The ANPRM is 

intended to provide transparency and the opportunity for public comment. 

5.2 Global Market-Based Measure

In October 2013, the 38th ICAO Assembly adopted a comprehensive climate change resolution 

(A38-18). This resolution created a commitment, among others, to develop a global marketbased measure (GMBM) to address GHG emissions from international aviation. The USG 

strongly supported the final resolution and is committed to pursuing development of a proposal 

for a GMBM to serve as a gap filler to address international aviation GHG emissions. 

International collaboration with States, industry, and NGO stakeholders has been instrumental 

to moving the process forward. 

Specifically, the USG is actively engaged, participating, and providing resources toward the 

development of the GMBM through analyses of potential design elements of a GMBM, 

estimated CO2 emissions, and potential impact of the GMBM on international aviation. The 

USG participates in the CAEP GMBM Technical Task Force (GMTF) to further examine design 

elements of a GMBM, such as systems used to monitor, report, and verify emissions, and define

criteria of emissions units that would be eligible for international aviation. The USG also 

participates in the Environmental Advisory Group (EAG), established by the ICAO Council to 

oversee work on the GMBM proposal development and provide recommendations to the

Council. The USG leads analytical and modeling efforts while working with other states to guide 

the direction of development of the GMBM. The USG will continue to provide support to 

complete the work that is necessary to the GMBM’s successful development and 

implementation.

5.3 NextGen Environmental Management System

The FAA has developed and is improving upon a NextGen Environmental Management System 

(EMS) Framework. The EMS will assist in measuring progress toward NextGen environmental 

goals and obtaining input from stakeholders (e.g., airports, airlines, and manufacturers) on 

improving environmental performance (e.g., reducing fuel burn and emissions from aviation). 

With the use of analytical models and information from stakeholders, the FAA can provide 

transparency and information regarding progress toward goals.

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U.S. Aviation Greenhouse Gas Emissions Reduction Plan

6 Scientific Understanding and Modeling/Analysis

35

The USG conducts a multi-faceted research program to better understand the environmental 

impacts of aircraft, including climate impacts from GHG and non-GHG emissions. Emissions of 

NOx, water vapor, and particulate matter from aircraft engines interact with the background 

atmosphere to produce contrails, changes to ozone and methane and secondary effects on 

cloud formation and destruction. The FAA supports research that will use satellite-derived 

contrail distributions to estimate the warming impacts of contrails more realistically. This data 

will help validate results from computer models that are being used to simulate contrail 

impacts. FAA-supported research will continue to lead to better understanding of current and 

future climate impacts of NOx emissions. Specifically, rigorous computer modeling efforts that 

capture cascading physical processes from smaller to larger scales are underway. 

Better understanding and quantification of climate impacts from research are continually being 

implemented in the FAA modeling and analysis tools to capture the costs and benefits of 

various policy options. The analytical methods and models used to assess the environmental 

impacts are regularly enhanced and improved. These tools are not only used to inform decision 

making but also to quantify the benefits of operational changes, future use of alternative jet

fuels, and technology improvements in a consistent framework in addition to noise and air

quality tools to better identify interdependencies and tradeoffs in mitigations. 
U.S. Aviation Greenhouse Gas Emissions Reduction Plan

One analysis conducted by the FAA explores how expected advancements in airframe and 

engine technology, alternative fuels, and operational improvements will propel the U.S. 

aviation sector towards USG environment and energy goals even with expected growth in 

operations. The study aims to provide insight into what, if any, gaps may need to be overcome 

when comparing sector’s current environmental performance with its goals, thus allowing the

FAA to better identify and prioritize the mitigation solutions that should be pursued. The 

analysis approach and results are presented in the following sections. As the underlying tools 

and assumptions are improved, this analysis will be refined and updated.

6.1 Analysis Background

The study methodology consists of developing a baseline (without action) scenario from an 

aviation forecast, processing this scenario in an environmental consequence tool, and applying 

system improvements to generate an expected results scenario that reflects the emissions 

impact of selected measures. Note that this is a system-wide analysis and thus the programs 

mentioned in prior sections of this action plan are not directly modeled as might be done in a 

“bottom-up” analysis. Rather, the study aims to capture the level of emissions reductions that 

can be expected from these system improvements in the aggregate. 

6.1.1 Forecasting

A seat class forecast was developed in coordination with the FAA Office of Aviation Policy and 

Plans (APO). This section describes the primary components of the forecasting process: (1) the 

Benefits Assessment U.S. Common Operations Database (COD) and (2) the Growth and 

Retirement process based largely on the FAA Terminal Area Forecast (TAF) and the CAEP 

Forecast and Economics Support Group (FESG) forecast.

Creation of the Benefits Assessment U.S. Common Operations Database of 2010 Flight 

Activity

The Benefits Assessment U.S. COD is a radar-derived record of flight activity in 2010 and is a 

primary input into the study’s flight forecasting process. The COD is derived from the FAA’s 

radar-based Traffic Flow Management System (TFMS), which captures most flights controlled 

under instrument flight rules. TFMS excludes: (1) most uncontrolled (visual) flights and (2) 

helicopter flights.

Growth and Retirement Process

The seat class forecasting process consists primarily of two steps: (1) growing the set of flights 

in the COD according to exogenous source forecasts, and (2) retiring aircraft to account for 

turnover in the fleet. These two processes—Growth and Retirement—are accomplished via a 

collection of databases and processing modules, of which the majority are in the public domain 

or in development at the FAA. Among these are the FAA Terminal Area Forecast (TAF), CAEP 

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U.S. Aviation Greenhouse Gas Emissions Reduction Plan

FESG retirement curves, and CAEP Fleet and Operations Module (FOM). The TAF is the FAA’s 

official forecast and is updated annually.16 The TAF covers domestic U.S. operations and U.S. 

international departures and arrivals. The initial in-service fleet is retired in future years 

according to CAEP FESG retirement curves. The FOM is a database processing application that 

outputs a forecast database containing: (1) flights performed by the initial (2010) in-service 

fleet and (2) flights performed by an unspecified set of newly deployed aircraft in a growth and 

replacement (G&R) fleet to be assigned subsequently in the modeling process. Figure 6-1

illustrates the Growth and Retirement Process. 

Figure 6-1 Growth and retirement process schematic diagram

6.1.2 Environmental Modeling

A pre-release version of the Aviation Environmental Design Tool (AEDT) Version 2b was used to 

process a baseline scenario of forecasted flights assuming no system improvements as defined 

below: 

• Airframe and engine technology did not advance but current vintage (circa 2010) aircraft

were used for fleet growth and replacement.

• Operational improvements had no net system improvement effect but were sufficient

to maintain operational inefficiency (i.e., delay) at recent historical levels.

• No alternative fuels were consumed.

The baseline scenario is not equivalent to the kind of “No-Investment” scenario that would be 

appropriate for a business case analysis. Analyses have shown that, without investment in 

NextGen, excess times per flight would be expected to eventually rise above recent historical 

levels.17 The study accounts for system improvements in post-AEDT processing, as described in 

the following section.

16 More information available at https://aspm.faa.gov/main/taf.asp 17 More information available at http://www.faa.gov/nextgen/media/Business_Case_for_NextGen_2013.pdf

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U.S. Aviation Greenhouse Gas Emissions Reduction Plan

6.1.3 System Improvement Assumptions

In the context of the analysis, “system improvement” denotes new technologies, infrastructure, 

or procedures that result in a net improvement in per-flight environmental and energy 

performance relative to historical levels. New technologies that only maintain system 

performance at historical levels are not considered “system improvements” in the context of 

the study. The study methodology considers three broad categories of “system improvements”: 

(1) airframe and engine improvements, (2) operational improvements, and (3) alternative fuels.

Multiple estimates for these improvements are represented in the analysis in order to provide a 

range on the output results that reflects uncertainty in the input assumptions.

Airframe and Engine Improvements

The project aircraft included in the system improvement scenario are based on technology 

packages assessed as part of the FAA’s CLEEN program. These packages consist of CLEENfunded technologies as well as other public domain and proprietary industry technologies 

potentially available in the CLEEN timeframe, including NASA N+1 and N+2 technologies. The 

vehicles were generated and assessed in the Environmental Design Space (EDS), an FAA-funded 

aircraft design and assessment tool.18 In the system improvements scenario, these vehicles 

were deployed into the growth and replacement fleet, resulting in emissions savings in future 

operations compared to the 2010 in-service fleet. Moderate and aggressive technology 

scenarios were developed for this analysis in order to reflect uncertainty in vehicle performance

(i.e., technology evolution) and the rate of technology insertion into the fleet.

Operational Improvements

The system improvements scenario is idealized in terms of operational performance in that

flights progressed over the analysis period toward great-circle flight paths—i.e., aircraft flew 

the shortest possible lateral distance between origin and destination—as well as unimpeded 

travel where no delay during the taxi phase is incurred. These operational conditions are not 

likely to be achievable in practice, but rather illustrate the potential for improvement with 

respect to spatial efficiency and idle time. 

The results also include data points reflecting quantitative assessments performed by the FAA 

NextGen Systems Analysis & Modeling Office to estimate the expected impacts of NAS 

modernization. These assessments aid with the selection, prioritization, and evaluation of 

NextGen technologies, procedures, and financing mechanisms. They also support NextGen 

planning documents, such as The Business Case for the Next Generation Air Transportation 

System.

19 The data points are included in the results in order to benchmark the idealized 

assumption for operational improvements. 

18 More information available at http://www.faa.gov/about/office_org/headquarters_offices/apl/research/models/eds/ 19 The Business Case for the Next Generation Air Transportation System available at 

http://www.faa.gov/nextgen/media/BusinessCaseForNextGen-2014.pdf

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U.S. Aviation Greenhouse Gas Emissions Reduction Plan

Alternative Fuels

The system improvement scenarios leverage the Billion Ton Study from the U.S. Department of 

Energy.20 This study quantified the amount of biomass that could be produced between now 

and 2030 within the continental United States from agricultural/forestry industry activity 

residues and wastes, as well as from dedicated energy crops. The study used an agricultural 

policy modeling system of U.S. agriculture, including both crops and livestock, that is based on 

data from the USDA. 

Two of the cases from the Billion Ton Study are used for the system improvement scenarios. 

The first considers a nominal biomass price of $40/ton, which results in 243 million tons of 

biomass being available in 2030 from agricultural residues and waste (52% of the total 

biomass), forestry residues and wastes (34%), and energy crops (14%). The second examines a 

nominal biomass price of $60/ton, which results in 767 million tons of biomass being available 

in 2030 from energy crops (52% of the total biomass), agricultural residues and waste (35%), 

and forestry residues and wastes (13%). These two scenarios were combined with assumptions 

that one third of the biomass would be converted to alternative jet fuels at a conversion 

efficiency of 45 gallons/ton. This yields 3.6 and 11.5 billion gallons of alternative jet fuel per 

year in 2030, respectively, for the two biomass prices. The Billion Ton Study also considered a 

high yield scenario wherein crop yields increased by as much as 4% per year. Under this 

scenario and the aforementioned assumptions, there would be 14.7 billion gallons of 

alternative jet fuel available in 2030.

For the purposes of the system improvement scenarios, the fuels were assumed to provide a 

life cycle CO2 emissions reduction of 75% relative to conventional jet fuels.21 Finally, linear 

extrapolation was used from 2030 to 2050, which roughly corresponds to an annual growth in 

yields of 3%. 

6.2 Analysis Results

Figure 6-2 and Figure 6-3 present the system performance results for the baseline and system 

improvement scenarios as compared to the FAA aspirational goal of carbon-neutral growth by 

2020 relative to 2005 levels. The moderate system improvement assumptions for technology 

and alternative jet fuel are represented in Figure 6-2, and the aggressive system improvement 

assumptions are represented in Figure 6-3. A life-cycle basis for computing CO2 emissions is 

used rather than relying on tailpipe emissions alone; without this interpretation, alternative jet 

fuels would not have a large effect on the relative carbon-dioxide intensity associated with jet 

fuel consumption. The division between combustion and non-combustion CO2 emissions for 

conventional jet fuel is illustrated in the callout bar chart in the figures.

20 Billion Ton Study available at http://www1.eere.energy.gov/bioenergy/pdfs/billion_ton_update.pdf 21 This reduction is in line with the CO2 life cycle calculations of waste and energy crop conversion to FT jet fuel from Stratton et al. (2010), 

available at http://web.mit.edu/aeroastro/partner/reports/proj28/partner-proj28-2010-001.pdf

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U.S. Aviation Greenhouse Gas Emissions Reduction Plan

Figure 6-2 Projected life-cycle CO2 emissions impacts – moderate system improvement 

scenario22

Life-Cycle 

CO2

Emissions

(as percent 

of 2005 

level)

40

 

The analysis indicates an emissions reduction potential from the baseline scenario of 

approximately 53 percent in 2040 for the moderate improvement scenario and 98 percent in 

2040 for the aggressive improvement scenario due to airframe and engine improvements, 

operational improvements, and alternative jet fuels. The results shown in the figure represent 

all U.S. operations, domestic and international. Regarding the NextGen benchmark data points, 

the assessment shows a benefit equivalent to 48 percent and 85 percent of the idealized 

operational improvement benefit in the years 2025 and 2030, respectively. Though there are 

uncertainties in the forecast and system improvement assumptions, the analysis gives an 

indication of how much progress is needed in order to approach FAA climate and energyefficiency goals. While the analysis indicates that significant progress can be made toward the 

USG’s aspirational climate goals, challenges remain to reach the levels of operational 

improvement, technology improvement, and alternative fuel availability reflected in these 

22 Note that combustion/tailpipe emissions are those created by the airline industry, while feedstock production, transportation, and fuel 

production emissions for conventional jet fuel are created by the petroleum extraction and refining industries. The emissions from alternative jet 

fuels would result in a net reduction in the CO2 emissions from fuel production and use. The scenario does not imply that the upstream emissions 

are attributable to airlines, rather than to jet fuel producers and others in the supply chain.
U.S. Aviation Greenhouse Gas Emissions Reduction Plan

scenarios, and it will take concerted USG and aviation industry efforts to work through these 

challenges. Significant work is being done under the Aviation Sustainability Center (ASCENT)—a 

Center of Excellence for Alternative Jet Fuel and Environment—to provide additional analyses 

to improve upon the assumptions that underpin this study. Specifically, ASCENT has initiated 

research projects in the areas of alternative jet fuel supply chains, aircraft technology modeling, 

and rapid fleet-wide assessment. As the analysis assumptions are refined through this work, 

further insight will be gained into the contribution of various improvement areas to the overall 

environmental performance of U.S. aviation and into the gaps that need to be overcome in 

pursuit of aspirational goals.

Figure 6-3 Projected life-cycle CO2 emissions impacts – aggressive system improvement 

scenario

Life-Cycle 

CO2

Emissions

(as percent 

of 2005 

level)

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U.S. Aviation Greenhouse Gas Emissions Reduction Plan

7 Summary

42

The United States is committed to addressing the climate impacts of commercial aviation 

through an integrated strategy of technology, operations, and policy innovation. This action 

plan details the USG measures to reduce GHG emissions through improved airframe and engine 

technology, more efficient aircraft operations, and development and deployment of alternative 

jet fuels, all in support of working towards the aspirational goal of carbon-neutral growth for 

U.S. commercial aviation by 2020, using 2005 emissions as a baseline. The plan leverages 

interagency cooperation as well as a number of public-private partnerships to enable a safe, 

efficient, and sustainable aviation system. The analysis presented in this document shows that 

significant progress can be made toward the USG’s aspirational climate goals through aviation 

system improvements. This document will be updated on a three-year cycle in order to 

continue to monitor and report on progress and to communicate further plans for ensuring 

sustainable aviation growth.