oversight

Aviation and the Environment: Strategic Framework Needed to Address Challenges Posed by Aircraft Emissions

Published by the Government Accountability Office on 2003-02-28.

Below is a raw (and likely hideous) rendition of the original report. (PDF)

                United States General Accounting Office

GAO             Report to the Chairman, Subcommittee
                on Aviation, Committee on
                Transportation and Infrastructure,
                House of Representatives

February 2003
                AVIATION AND THE
                ENVIRONMENT
                Strategic Framework
                Needed to Address
                Challenges Posed by
                Aircraft Emissions




GAO-03-252
                                               February 2003


                                               AVIATION AND THE ENVIRONMENT

                                               Strategic Framework Needed to Address
Highlights of GAO-03-252, a report to the
Chairman, Subcommittee on Aviation,
                                               Challenges Posed by Aircraft Emissions
House Committee on Transportation and
Infrastructure




 Although noise has long been a                Many airports have taken measures to reduce emissions, such as converting
 problem around airports, the                  airport ground vehicles from diesel or gasoline to cleaner alternative fuels. While
 anticipated growth in demand for              the actual impact of these measures is unknown, some measures (such as
 air travel has also raised questions          shifting to cleaner alternative fuels) have the potential to significantly reduce
 about the effect of airport                   emissions, such as nitrogen oxides. In some cases—such as at Los Angeles and
 operations on air quality. Aviation-          Dallas/Fort Worth airports—the emission reduction measures have been
 related emissions of nitrogen                 imposed by federal or state agencies to bring severely polluted areas into
 oxides, which contribute to the               attainment with the Clean Air Act’s air quality standards or to offset expected
 formation of ozone, have been of              increases in emissions from airport expansion projects. Many industry and
 particular concern to many airport
                                               government officials that GAO contacted said that new, stricter federal air
 operators. A federal study at 19
 airports estimated that, by 2010,             quality standards that will go into effect in 2003, combined with a boost in
 aircraft emissions have the                   emissions due to an expected increase in air travel, could cause airports to be
 potential to significantly                    subject to more federal emission control requirements. In 1998, a group of
 contribute to air pollution in the            government and industry stakeholders was established to develop a voluntary
 areas around these airports.                  nationwide program to reduce aviation-related emissions; however, thus far, the
                                               group has not agreed to specific objectives or elements of a program.
 GAO agreed to review efforts in
 the United States and other                   Other countries use many of the same measures as the United States to reduce
 countries to reduce emissions at              emissions at airports. Two countries have imposed landing fees based on the
 airports and the effect of                    amount of emissions produced by aircraft. However, U.S. officials question the
 improvements in aircraft and
                                               effectiveness of these fees.
 engine design on emissions.
                                               Research and development efforts by the federal government and the aircraft
                                               industry have improved fuel efficiency and reduced many emissions from
 GAO recommends that the                       aircraft, including hydrocarbons and carbon monoxide, but have increased
 Federal Aviation Administration               emissions of nitrogen oxides, which are a precursor to ozone formation. As a
 (FAA) develop a strategic                     result, many new aircraft are emitting more nitrogen oxides than the older
 framework that addresses the                  aircraft they are replacing. For example, GAO’s analysis of aircraft emission data
 need for information on the extent            shows that the engines employed on the newest models of a widely used jet
 and impact of emissions, identifies           aircraft, while meeting current standards for nitrogen oxides emissions, average
 reduction options, establishes                over 40 percent more nitrogen oxides during landings and takeoffs than the
 goals and time frames for                     engines used on the older models. Technologies are available to limit nitrogen
 achieving needed reductions, and
                                               oxides emissions from some other newer aircraft models. Many state and federal
 defines the roles of government
 and industry in developing and                officials GAO contacted said that, in the long term, nitrogen oxides emissions
 implementing reduction programs.              from aircraft will need to be reduced as part of broader emission reduction
                                               efforts in order for some areas to meet federal ozone standards.

                                               Aircraft line up to take off




www.gao.gov/cgi-bin/getrpt? GAO-03-252.

To view the full report, including the scope
and methodology, click on the link above.
For more information, contact Gerald L
Dillingham at (202) 512-3650 or
DillinghamG@gao.gov.
Contents


Letter                                                                                    1
               Results in Brief                                                           2
               Background                                                                 4
               Airports and Airlines are Taking a Variety of Actions to Reduce
                 Emissions, Although Specific Impact of These Actions Unknown            7
               Two Countries Have Introduced Emission-Based Fees                        18
               Improvements in Aircraft and Engine Design Have Reduced Many
                 Aircraft Emissions, but Nitrogen Oxide Emissions are Increasing        21
               Conclusion                                                               31
               Recommendation for Executive Action                                      31
               Agency Comments                                                          32

Appendix I     Objectives, Scope, and Methodology                                       34



Appendix II    Types, Amounts, and Impact of Emissions from
               Aviation-related Sources                                                 38
               Aviation-Related Emissions and Sources                                   38
               Health and Environmental Impact of Pollutants                            41

Appendix III   Federal, State, and International Responsibilities
               for Controlling Aviation-related Emissions                               45



Appendix IV    Efforts by Three States to Reduce Aviation-related
               Emissions                                                                49
               California                                                               49
               Texas                                                                    50
               Massachusetts                                                            52

Appendix V     Airports’ and Airlines’ Efforts To Reduce Emissions                      54
               Aircraft                                                                 54
               Ground Support Equipment                                                 54
               Providing Electric Power at Gates                                        56
               Passenger Vehicles                                                       56
               Other Measures                                                           57




               Page i                               GAO-03-252 Aviation and the Environment
Appendix VI     Overview of Aircraft Fuel, Noise, and Nitrogen
                Oxide Reduction Technologies                                             59



Appendix VII    Additional Information on Our Analysis of Aircraft
                Emissions                                                                64



Appendix VIII   Comments from the National Aeronautics and
                Space Administration                                                     69



Appendix IX     GAO Contacts and Staff Acknowledgments                                   70
                GAO Contacts                                                             70
                Staff Acknowledgments                                                    70


Tables
                Table 1: Aircraft Turbine Engine Emission Amounts during
                         Cruising Per 1000 Grams of Fuel Burned                          22
                Table 2: Comparison of Emissions during Landing/Takeoff for
                         Older and the Newest Model Boeing 737s                          23
                Table 3: Comparison of Boeing 747 and 777 Emissions on a Per
                         Aircraft Basis                                                  24
                Table 4: Comparison of Boeing 747 and 777 Emissions on a Per
                         Seat Basis                                                      24
                Table 5: Comparison of Power, Engine Operating Pressures, and
                         Nitrogen Oxides Emissions for Two Models of Boeing
                         737s                                                            26
                Table 6: Health and Environmental Effects of Air Pollutants              44
                Table 7: Emission Information for Older Boeing 737s during
                         Landing/Takeoff                                                 65
                Table 8: Emission Information for Newest Boeing 737s during
                         Landing/Takeoff                                                 66
                Table 9: Additional Information on Comparison of Older and
                         Newest Model Boeing 737 Landing/Takeoff Emissions               66
                Table 10: Additional Information on Comparison of Boeing 747 and
                         777 Emissions on a Per Aircraft Basis                           67



                Page ii                              GAO-03-252 Aviation and the Environment
          Table 11: Comparison of Power, Engine Operating Pressures, and
                  Nitrogen Oxides Emissions for a Boeing 737-300 and Its
                  Most Common Replacement                                                           68


Figures
          Figure 1: Examples of Activities to Reduce Emissions                                       9
          Figure 2: NASA’s Planned Funding for Nitrogen Oxide Research                              28
          Figure 3: Major Components of a Turbofan Engine (Two-Shaft High
                   Bypass Engine)                                                                   60




          Abbreviations

          DOT               Department of Transportation
          EDMS              Emissions and Dispersion Modeling System
          EPA               Environmental Protection Agency
          FAA               Federal Aviation Administration
          GAO               General Accounting Office
          ICAO              International Civil Aviation Organization
          NASA              National Aeronautics and Space Administration



          This is a work of the U.S. Government and is not subject to copyright protection in the
          United States. It may be reproduced and distributed in its entirety without further
          permission from GAO. It may contain copyrighted graphics, images or other materials.
          Permission from the copyright holder may be necessary should you wish to reproduce
          copyrighted materials separately from GAO’s product.




          Page iii                                       GAO-03-252 Aviation and the Environment
United States General Accounting Office
Washington, DC 20548




                                   February 28, 2003

                                   The Honorable John L. Mica
                                   Chairman
                                   Subcommittee on Aviation
                                   Committee on Transportation and Infrastructure
                                   House of Representatives

                                   Dear Mr. Chairman:

                                   Although aviation-related activities result in the emission of pollutants that
                                   account for only about 0.5 percent of total air pollution in the United
                                   States, these pollutants are among the most prevalent and harmful in the
                                   atmosphere and are expected to grow. The Federal Aviation
                                   Administration (FAA) expects the demand for air travel in the United
                                   States to recover from the events of September 11, 2001, and then continue
                                   a long-term trend of 3.6 percent annual growth. This expected growth has
                                   heightened concerns among some communities, environmental groups,
                                   and others that airport operations will have an increasingly detrimental
                                   effect upon the environment. Although, to date, these groups have focused
                                   primarily on the noise generated by aircraft operations, they are becoming
                                   increasingly concerned about aviation’s impact on air quality. Our August
                                   2000 report found that the operators of the nation’s 50 busiest airports
                                   considered that air quality issues would become a bigger concern and
                                   challenge for them in the future than any other environmental issue.1
                                   Airport operators were particularly mindful of the effects on air quality of
                                   the increases in emissions due to airport growth. The emissions of most
                                   concern to many airport operators, as well as to many state and local air
                                   quality authorities, are nitrogen oxides, which are a primary contributor to
                                   the formation of ozone, a major pollutant in many metropolitan areas.

                                   You asked us to provide information on how the aviation community is
                                   addressing current and future concerns about air quality. Specifically, you
                                   asked the following questions: (1) What efforts are being undertaken to
                                   reduce emissions from airport activities, and what are the outcomes of
                                   these efforts? (2) What additional efforts are being undertaken in other



                                   1
                                    U. S. General Accounting Office, Aviation and the Environment: Airport Operations and
                                   Future Growth Present Environmental Challenges, GAO/RCED-00-153 (Washington, D.C.:
                                   Aug. 30, 2000).



                                   Page 1                                       GAO-03-252 Aviation and the Environment
                   countries to reduce aviation-related emissions? and (3) How have
                   improvements in aircraft and engine design affected aircraft emissions?

                   To address these questions, we reviewed the results of environmental
                   reviews conducted over the past 3 years at major airports located in areas
                   (called nonattainment areas) that have not attained air quality standards
                   required by the Clean Air Act; surveyed air quality officials from the 13
                   states that have major airports in nonattainment areas; and visited seven
                   airports. To identify trends in aircraft emissions, we analyzed aircraft
                   landing and takeoff data for the U.S. commercial aircraft fleet in 2001
                   using a computer model developed by FAA. In addition, we interviewed
                   and gathered information from officials representing FAA, the
                   Environmental Protection Agency (EPA), the National Aeronautics and
                   Space Administration (NASA), the International Civil Aviation
                   Organization (ICAO), airlines, aircraft manufacturers, and state and local
                   governments. We also reviewed previous reports on aviation emission
                   issues and available information on international efforts to reduce aviation
                   emissions. We conducted our work from September 2001 through
                   February 2003 in accordance with generally accepted government auditing
                   standards. See appendix I for additional information on our objectives,
                   scope, and methodology.


                   Many of the nation’s busiest airports and airlines have taken actions to
Results in Brief   reduce the emissions from airport activities, such as converting shuttle
                   buses to alternative fuels, decreasing the taxiing time of aircraft, and
                   providing electricity to aircraft parked at gates, thereby allowing aircraft
                   to turn off their more polluting power units while crews prepare the
                   aircraft for the next flight. Although the actual impact of these measures is
                   unknown, some measures have the potential to significantly reduce
                   emissions from certain sources. For example, an initiative at Dallas/Fort
                   Worth International and Houston airports to convert ground service
                   equipment from diesel and gasoline to electric and alternative fuel engines
                   is expected to cut nitrogen oxides emissions from such equipment by up
                   to 75 percent. In some cases, federal or state agencies have imposed
                   emission reduction measures on airports located in severely polluted areas
                   (called nonattainment areas) to help bring these areas into attainment with
                   the air quality standards of the Clean Air Act, or to offset expected
                   increases in emissions from airport expansion projects. In other cases,
                   airports or airlines have voluntarily undertaken the measures. For
                   example, the ozone pollution in the Los Angeles metropolitan area has
                   prompted the state to require emission reductions from all sources,
                   including airports. State and local air quality agencies have negotiated with


                   Page 2                                  GAO-03-252 Aviation and the Environment
airlines that use five local airports, including Los Angeles International, to
replace older, highly polluting ground support equipment—such as
baggage handling and food service vehicles—with newer, less polluting
equipment. State officials expect this action to reduce emissions from
ground support equipment at the five airports by 80 percent. In addition,
our analysis of the environmental reviews conducted by FAA at major
commercial airports located in nonattainment areas found that most
proposed airport construction projects were not required to institute any
emission reduction measures to comply with emission standards.
However, FAA officials told us that in the future, approval of some
projects in these areas may be less likely because of several factors,
including increased focus on air quality by communities that oppose
airport development. In addition, in 1998, a group of government and
industry stakeholders was established to develop a voluntary nationwide
program to reduce aviation-related emissions however, thus far the group
has not defined specific objectives or established time frames for
achieving emissions reductions. In 2003, EPA plans to begin implementing
stricter ambient air quality standards for ozone and other pollutants,
which could make it more difficult for some localities to achieve or
maintain the standards. Many in the aviation industry as well as federal
and state officials believe that the new standards, combined with the boost
in emissions expected from increases in air travel, could cause airports to
be subject to more federal emission control requirements in the future.
Currently, 26 of the 50 busiest U.S. airports are located in areas that are
not attaining the current 1-hour ozone standard; however, that number
could increase to 38 under the stricter 8-hour ozone standard, according to
EPA estimates.

Other countries use many of the same measures to reduce emissions at
airports as the United States and, in addition, two countries have imposed
landing fees based on the amount of emissions produced by aircraft.
Switzerland and Sweden recently implemented emission-based landing fee
systems as incentives for air carriers to reduce emissions from aircraft
using airports in those countries. It is too soon to determine whether the
fee systems have reduced emissions at these airports, although FAA
officials question the effectiveness of such fees in reducing emissions. One
U.S. airport, Boston Logan International, considered emission-based
landing fees in 2001, but decided they would not be a practical option for
reducing emissions—particularly nitrogen oxides—because the fees
would probably be too low to influence carriers’ use of lower-emitting
aircraft.




Page 3                                  GAO-03-252 Aviation and the Environment
             Research and development by NASA and aircraft and engine
             manufacturers have led to engine and airframe improvements that have
             increased fuel efficiency and yielded environmental benefits, such as
             reduced carbon monoxide and other emissions. However, trade-offs
             among several factors, including engine performance, have also led to
             increases in emissions of nitrogen oxides, which are a precursor to ozone
             formation. As a result, some of the newest aircraft are emitting more
             nitrogen oxides than the older, noisier, and less fuel-efficient aircraft they
             are replacing. For example, our estimate of emissions produced by the
             U.S. commercial aircraft fleet in 2001 indicates that the engines used on
             the newest Boeing 737 models, which are widely used for domestic flights,
             average over 40 percent more nitrogen oxides emissions during landings
             and takeoffs than the engines primarily used on older-model Boeing 737s.
             Technologies are being introduced that limit nitrogen oxides emissions
             from some other newer aircraft models. Many state and federal officials
             we contacted stated that, in the long term, nitrogen oxides emissions from
             commercial aircraft will need to be reduced as part of broader emission
             reduction efforts in order for some areas to meet ozone standards. Both
             the environmental and aviation communities have also voiced concerns
             that emissions from aircraft, particularly nitrogen oxides, need to be
             further reduced. NASA, in association with the aviation community, is
             working on technologies to reduce emissions of nitrogen oxides, but it is
             unclear if such technologies can be introduced on commercial aircraft in
             the foreseeable future.

             To address the growing impact of aviation on air quality and the lack of
             progress by the stakeholders group, we recommend that FAA develop a
             strategic framework that examines the extent and impact of nitrogen
             oxides and other aviation-related emissions; considers the
             interrelationship among emissions and between emissions and noise;
             includes goals, time frames, and options for achieving emission
             reductions; and specifies the roles of other government agencies and the
             aviation industry in developing and implementing emission reduction
             programs. FAA, EPA, and NASA generally agreed with our findings, and
             FAA agreed with our recommendation.


             Although aviation-related activities currently account for only 0.5 percent
Background   of total air pollution in the United States, the types of pollutants emitted by
             these activities are among the most prevalent and harmful in the
             atmosphere, and are expected to grow over time. The major sources of
             aviation-related emissions are aircraft, which emit pollutants at ground
             level as well as over a range of altitudes; the equipment (such as vehicles


             Page 4                                   GAO-03-252 Aviation and the Environment
that transport baggage) that services them on the ground at airports; and
vehicles transporting passengers to and from the airport. The amount of
emissions attributable to each source varies by airport. A 1997 study of
mobile source emissions at four airports found that ground access vehicles
were the most significant source (accounting for 27 to 63 percent of total
mobile source emissions), followed by aircraft (15 to 38 percent of the
total) and ground service equipment (12 to 13 percent of the total).2 The
emissions produced by these sources include carbon monoxide; sulfur
dioxide; particulate matter; toxic substances (such as benzene and
formaldehyde); and nitrogen oxides and volatile organic compounds,
which contribute to the formation of ozone, a major pollutant in many
metropolitan areas. In addition, aircraft emit carbon dioxide and other
gases that have been found to contribute to climate change due to
warming. According to the United Nations’ Intergovernmental Panel on
Climate Change, global aircraft emissions accounted for approximately 3.5
percent of the warming generated by human activities. (The types,
amounts, and impact of emissions from aviation-related sources are
described in detail in appendix II.)

Although only limited research has been done on the impact of projected
growth in air travel on emissions, indications are that emissions are likely
to continue increasing. FAA reported in June 2001 that the number of
commercial flights is expected to increase about 23 percent by 2010 and
about 60 percent by 2025.3 Each flight represents a takeoff and landing
cycle during which most aircraft emissions enter the local atmosphere. In
addition, an EPA study of 19 airports projected that the proportion of
mobile-source emissions of nitrogen oxides attributable to aircraft in the
areas adjacent to these airports will triple from a range of 0.6 to 3.6
percent in 1990 to a range of 1.9 to 10.4 percent in 2010.4 Such projections,
however, do not consider recent industry changes, such as airlines’



2
 Energy and Environmental Analysis, Inc. for Industrial Economics submitted to EPA
Analysis of Techniques to Reduce Air Emissions at Airports (Draft Final Report)
(Washington, D.C.: June 1997).
3
 Federal Aviation Administration, FAA Long-Range Aerospace Forecasts Fiscal Years
2015, 2020 and 2025, FAA-APO-01-3 (Washington, D.C.: June 2001).
4
 ICF Consulting Group, Evaluation of Air Pollutant Emissions from Subsonic
Commercial Jet Aircraft, EPA420-R-99-013 (Washington, D.C.: April 1999). In this report,
which was prepared for EPA, the agency acknowledged that some groups, including the air
transport industry were critical of the growth projections, fleet turnover assumptions, and
emissions estimates used in the report. As a result, these groups believe the report
overstates the amount of emissions generated by aircraft.



Page 5                                         GAO-03-252 Aviation and the Environment
increased use of smaller aircraft and the financial uncertainties in the
aviation industry. A recent report by the Department of Transportation
indicated that the September 11, 2001, terrorist attacks, combined with a
cut-back in business travel, had a major and perhaps long-lasting impact
on air traffic demand.5

A number of federal, state, and international agencies are involved in
controlling aviation-related emissions. The Clean Air Act6 mandates
standards for mobile sources of emissions such as aircraft, ground service
equipment, and automobiles. As mandated by the act, EPA promulgates
emission standards for aircraft, and has chosen to adopt international
emission standards for aircraft set by ICAO, which was chartered by the
United Nations to regulate international aviation and includes the United
States and 188 other nations. As the United States’ representative to ICAO,
FAA, in consultation with EPA, works with representatives from other
member countries to formulate the standards. EPA and FAA work to
ensure that the effective date of emissions standards permit the
development and application of needed technology and give appropriate
consideration to the cost of compliance, according to FAA officials. The
officials also noted that EPA is responsible for consulting with FAA
concerning aircraft safety and noise before promulgating emission
standards. In addition to issuing aircraft emission standards, ICAO has
studied aviation-related emission issues and issued guidance to its
members on ways to reduce these emissions.

States can address airport emissions in plans, known as state
implementation plans, 7 that they are required to submit to EPA for
reducing emissions in areas that fail to meet the National Ambient Air
Quality Standards set by the EPA under the Clean Air Act for common air
pollutants with health and environmental effects (known as criteria
pollutants).8 Geographic areas that have levels of a criteria pollutant above


5
 Department of Transportation, Office of the Inspector General, Airline Industry Metrics
(Washington, D.C.: January 7, 2003).
6
42 U.S.C. 7401-7626.
7
 State implementation plans are based on analyses of emissions from all sources in the area
and computer models to determine whether air quality violations will occur. If data show
that air quality standards will be exceeded, the states are required to impose controls on
existing emission sources to prevent this situation.
8
 The criteria pollutants are carbon monoxide, lead, nitrogen dioxide, particulate matter,
ozone, and sulfur dioxide.




Page 6                                          GAO-03-252 Aviation and the Environment
                          those allowed by the standard are called nonattainment areas. Areas that
                          did not meet the standard for a criteria pollutant in the past but have
                          reached attainment and met certain procedural requirements are known as
                          maintenance areas. The options available to states for controlling
                          pollution from airports are limited because most emissions come from
                          mobile sources, such as automobiles, which are already regulated by EPA,
                          and states are generally preempted from issuing regulations on aircraft
                          emissions because of EPA’s federal responsibility in this area. FAA is
                          responsible for enforcing the emission standards and for ensuring that
                          emissions resulting from airport construction projects under their
                          authority comply with the National Environmental Policy Act, which
                          requires an environmental review of such projects, and the Clean Air Act’s
                          requirement that the projects comply with state implementation plans for
                          attaining air quality standards. (See appendix III for additional information
                          on federal, state, and international responsibilities concerning aviation-
                          related emissions.)


                          Many of the nation’s busiest airports and airlines that serve them have
Airports and Airlines     initiated voluntary emission reduction measures, such as converting
are Taking a Variety of   shuttle buses and other vehicles from diesel or gasoline fuels to cleaner
                          alternative fuels. While the actual impact of these measures is unknown,
Actions to Reduce         some measures (such as shifting to new cleaner gas or diesel engines or
Emissions, Although       alternative fuels) have the potential to significantly reduce emissions, such
                          as nitrogen oxides, volatile organic compounds, particulate matter, and
Specific Impact of        carbon monoxide. The airports and airlines have undertaken these efforts
These Actions             for a variety of reasons, including requirements by states imposed as part
Unknown                   of their plans to ensure that severely polluted areas (i.e., nonattainment
                          areas) achieve the air quality standards established by the Clean Air Act
                          and to gain federal approval for airport construction projects. In late 2003,
                          EPA will begin implementing stricter standards for ozone, which could
                          make it more difficult for areas to achieve or maintain attainment status.
                          Representatives from the aviation industry as well as federal and state
                          officials told us that the new air quality standards, combined with the
                          boost in emissions expected from increases in air travel, could cause
                          airports to be subject to more emission control requirements in the future.
                          In addition, according to FAA officials, approval of some projects in these
                          areas may be less likely because of several factors, including increased
                          focus on air quality by communities that oppose airport development.




                          Page 7                                  GAO-03-252 Aviation and the Environment
Airports’ and Airlines’   Many of the nation’s busiest airports, in conjunction with the air carriers
Voluntary Actions to      that serve them, have implemented voluntary control measures to reduce
Reduce Emissions          emissions from major sources, including aircraft, ground support
                          equipment, and passenger vehicles entering and exiting the airport,
                          according to our review of FAA documents and interviews with airport
                          and state environmental officials. Specific guidelines or regulations for
                          airports to reduce emissions from these sources do not exist, but some
                          airports have been proactive in developing programs and practices that
                          reduce emissions. Although the actual impact of these measures is
                          unknown, some initiatives have the potential to significantly reduce
                          emissions from certain sources. For example, a number of carriers at
                          Dallas/Fort Worth International and Houston airports have agreed to
                          voluntarily reduce emissions associated with ground service equipment by
                          up to 75 percent. Figure 1 provides examples of activities to reduce
                          emissions that have been implemented at U.S. airports. Appendix V
                          provides more information on some airports’ voluntary efforts to reduce
                          emissions.




                          Page 8                                 GAO-03-252 Aviation and the Environment
Figure 1: Examples of Activities to Reduce Emissions




                                        Note: The information presented in this chart is not meant to include all activities for reducing
                                        emissions at airports. According to FAA, there are gaps in understanding how such activities effect
                                        various emissions, including various interrelationships among the emissions and their effects.


Most States Have Not                    Only 3 of the 13 states with major commercial airports in nonattainment
Included Airports in Their              areas—California, Texas, and Massachusetts—have targeted airports for
Emission Control                        emission reductions. The remaining states have not included emission
                                        reductions at airports as part of their strategies for bringing nonattainment
Strategies                              areas into compliance with the Clean Air Act’s ambient air quality
                                        standards because they have attempted to achieve sufficient reductions
                                        from other pollution sources. Officials from these states noted that EPA



                                        Page 9                                               GAO-03-252 Aviation and the Environment
has the authority to set emission standards for aircraft and nonroad
vehicles, including ground support equipment at airports, which preempts
the states’ regulation of these sources.

California and Texas face major ozone nonattainment problems—
California in the Los Angeles metropolitan area and Texas in the Dallas-
Fort Worth and Houston metropolitan areas. According to air quality
officials from both states, even after imposing all of the traditional
emission control measures available, such as vehicle emission inspections,
the three metropolitan areas still may not be able to reach attainment
status for ozone by the 2010 deadline for Los Angeles and by the 2005 and
2007 deadlines for Dallas-Fort Worth and Houston, respectively. Despite
potential legal challenges from airlines, both California and Texas turned
to airports for additional emission control measures. Texas has negotiated
an agreement with the Dallas/Fort Worth International and Houston
airports and the airlines that serve them to reduce emissions attributable
to ground support equipment by 90 percent. California has reached a
similar agreement with the major airlines serving the five commercial
airports in the Los Angeles nonattainment area to reduce emissions from
ground support equipment.

California’s efforts to cut ground support equipment emissions in the Los
Angeles area are part of a statewide campaign to reduce airport pollution.
In addition to using its limited authority under the Clean Air Act to
implement airport-related emission reductions, the state has also
employed a certification process provided for in federal law.9 Under this
provision, before FAA can approve a grant for any new airport, new
runway, or major runway extension project, the governor must certify that
the project complies with applicable air and water quality standards.
California has developed criteria for determining whether a proposed
airport expansion project would have an impact on the environment,
including air quality. Unlike other states, California uses the criteria as a
mandatory condition for project certification. If the project exceeds one of
the criteria—by increasing the number of passengers, aircraft operations,
or parking spaces and thereby producing an impact on the environment—
the airport is required to implement emission mitigation measures in order
to attain certification. Thus far, three airports—Sacramento International,
San Jose International, and Ontario International—have initiated
expansion projects that were required to comply with the certification


9
49 U.S.C. section 47106.




Page 10                                 GAO-03-252 Aviation and the Environment
                            standards. However, in a legal opinion issued in August 2000, FAA’s Office
                            of Chief Counsel stated that California has no legal authority to impose
                            operational limitations on airports through the certification process.
                            According to FAA, California has not publicly responded to the opinion. A
                            California air quality official told us that the state disagrees with the
                            opinion and does not plan to change its certification process.

                            In 1999, Boston Logan International Airport began building a new runway
                            to reduce serious flight delays. As a condition for approving the project,
                            the state required the airport to cap emissions at 1999 levels (referred to as
                            a “benchmark”) because it has determined that the airport is a significant
                            contributor to Boston’s serious ozone problem. To stay within the limit,
                            the airport had considered reduction strategies that include charging
                            higher landing fees during peak operating times to reduce congestion and
                            the resulting emissions. Now that air traffic and emission levels have fallen
                            off since the events of September 11, 2001, the operator of the Boston
                            airport, the Massachusetts Port Authority, believes that peak pricing and
                            other emission reduction strategies will not be needed for several years to
                            keep emissions below 1999 levels. The Massachusetts Port Authority,
                            however, continues to work with airport tenants to implement voluntary
                            emission reduction strategies. More information on states’ efforts to
                            reduce emissions appears in appendix IV.


Proposed Airport Projects   In addition to facing control measures as part of state strategies to attain
Have Been Able to           the Clean Air Act’s ambient air quality standards, airports must also submit
Conform to Current Air      most major construction project proposals for federal environmental
                            review, which includes an evaluation of the proposed project’s impacts on
Quality Standards           air quality. The National Environmental Policy Act and the Clean Air Act
                            require that FAA perform environmental reviews of all airport projects
                            that involve the federal government, such as the construction of federally
                            subsidized runways. As part of this review process, FAA must determine
                            that emissions from projects at airports in nonattainment and maintenance
                            areas do not adversely interfere with states’ plans for the areas to reach
                            attainment.

                            We examined all environmental reviews conducted by FAA at major
                            commercial airports10 in nonattainment areas during the 3-year period 1998



                            10
                             Major commercial airports are the 50 busiest airports in 2001, based on air carrier
                            operations at those airports.




                            Page 11                                         GAO-03-252 Aviation and the Environment
to 2001. These reviews include those required by the National
Environmental Policy Act as well as those required under the Clean Air
Act to ensure compliance with state implementation plans for achieving
ambient air quality standards. During the period, FAA performed such
reviews at 24 of the 26 major commercial airports in nonattainment areas.
The projects reviewed included developing runways, expanding passenger
terminals and air cargo and airline support facilities, and developing
roadways and intersections on airport property.

Our analysis of airport environmental review documents showed that
while air quality issues are a significant consideration for airports planning
major development projects, emissions have not been a major obstacle in
gaining approval for projects; however, FAA is concerned that increasing
emissions from operations could jeopardize the approval of future
expansion projects. In 12 of the 24 cases we examined, the environmental
reviews stated that the airport expansion projects would not affect air
quality in the regions. The environmental reviews for 7 of these 12 projects
estimated that emissions would decrease as a result of improvements in
operational efficiency. For example, John F. Kennedy International Airport
expected its proposed passenger terminal, air cargo, and airline support
facilities expansion project to decrease the emission of nitrogen oxides by
207.2 tons per year by 2010 (about a 5-percent reduction in total airport
nitrogen oxides emissions11) because the project was expected to decrease
the amount of time aircraft take to taxi from the runway to the terminal.
For 8 of the projects, significant project-related emission increases
resulted from construction activities and, although the increases were
temporary, the airports were required, under EPA’s general conformity
rules, to adopt mitigation measures to allow FAA to determine that the
projects complied with state implementation plans. In only 3 cases, was a
significant permanent rise in emissions expected to result from the
project. Five airports —Atlanta Hartsfield, Dallas/Fort Worth International,
Los Angeles International, San Jose International, and Oakland
International—were required to reduce emissions from other sources in
order to mitigate the effects of the increased emissions expected from
either project construction or operations related to a project. Atlanta
Hartsfield, for example, committed to reduce emissions associated with
construction by requiring construction equipment to be operated with




11
  The reduction was calculated using total nitrogen oxides emissions from John L. Kennedy
International and LaGuardia Airports for 1999.




Page 12                                       GAO-03-252 Aviation and the Environment
                        catalytic converters that would reduce emissions and by using a massive
                        conveyor system to haul fill material, thereby minimizing the use of trucks.

                        Although most recent airport construction projects in nonattainment areas
                        met the requirements of the Clean Air Act, FAA officials noted that in the
                        future, approval of some projects in these areas could be in jeopardy if
                        state implementation plans did not make adequate allowances for
                        emissions that could result from growth in aviation-related activities or
                        include provisions for airports to offset future increases. FAA noted that
                        approval of projects is complicated by the fact that it is often difficult to
                        determine if a development project complies with the state
                        implementation plan because some plans do not contain an aviation
                        emission component, while other plans use a model or methodology to
                        calculate aviation emissions that is incompatible with FAA’s model to
                        determine a project’s compliance with air quality requirements. In
                        addition, FAA noted that approval of some projects may be complicated
                        by an increased focus on air quality by community groups that oppose
                        airport projects, the insistence of EPA and/or state and local air quality
                        agencies on mitigation measures when FAA has determined that proposed
                        projects will reduce emissions, and the general need to better understand
                        aviation emissions. According to FAA, approval of airport construction
                        projects may be further complicated by differences among federal and
                        state air quality standards, especially when state standards are more
                        restrictive, and differences among EPA and state/local air quality agencies
                        on the appropriate analysis and mitigation measures. Also, FAA officials
                        have noted an increasing trend for communities to demand under the
                        National Environmental Policy Act that FAA undertake and disclose the
                        effects of air toxics and health effects studies. Finally, although emissions
                        from construction activities are temporary, if they are above allowable
                        levels, FAA is required to undertake and issue a full determination that the
                        project/activity will conform to the state implementation plan.


Federal and State       FAA, EPA, and some states have developed programs to reduce emissions
Programs for Reducing   from aviation-related activities and established jointly with the aviation
Airport Emissions       industry a process that has tried to reach a voluntary consensus on how to
                        further reduce emissions. For example, as part of its Inherently Low-
                        Emission Airport Vehicle Pilot Program, required by Congress in 2000,12




                        12
                         49 U.S.C. section 47136.




                        Page 13                                 GAO-03-252 Aviation and the Environment
FAA awarded federal grants of up to $2 million to each of 10 airports13 for
alternative fuel vehicles and infrastructure. FAA is using the program to
evaluate the vehicles’ reliability, performance, and cost-effectiveness in
the airport environment. FAA initially anticipated that the program would
reduce emissions by 22,584 tons of ozone, 314,840 tons of carbon
monoxide, 384 tons of particulates, and 924 tons of sulfur dioxide during
the projected lifetime of the airport equipment. To achieve this reduction,
FAA expected the airports to purchase about 1,600 pieces of alternative
fuel ground support equipment and 600 alternative fuel ground access
vehicles, such as airport cars, buses, and shuttles. As of October 2002, FAA
reported a slower-than-expected start-up of the program, with only five
airports (Baltimore-Washington International, Dallas/Forth Worth
International, Baton Rouge Metropolitan, Sacramento International, and
Denver International) making notable progress on the program. According
to FAA, the effects of the events of September 11, 2001, have caused
unforeseen delays and acquisition deferrals for many low-emission vehicle
projects, particularly those that rely on airline financing to convert ground
support equipment to alternative fuels.

Although FAA plans to provide $17.3 million for the Inherently Low-
Emission Airport Vehicle Pilot Program, airports and air carriers
expressed the need for more federal funding to reduce emissions. Some
airports have said that they would like flexibility in how the Airport
Improvement Program14 or passenger facility charge15 funds can be used to
mitigate or offset emissions from expansion projects. For instance,
Sacramento Airport officials stated that they would like the city’s light rail
system to be connected to the airport to reduce emissions from ground
access vehicles. However, Airport Improvement Program or passenger
facility charge funds cannot be used for emission mitigation projects



13
  The 10 airports are Atlanta Hartsfield, Baltimore Washington International, Baton Rouge
Metropolitan, Denver International, Dallas/Fort Worth International, New York John F.
Kennedy International, New York LaGuardia, Chicago O’Hare International, San Francisco
International, and Sacramento International.
14
 FAA’s Airport Improvement Program provides grants to airports for capital development.
FAA allocates most grants on the basis of a legislated formula tied to the number of
passengers an airport enplanes and categories earmarked for specific types of airports and
projects.
15
  Most airports are able to charge passengers a boarding fee, called a passenger facility
charge, to help pay for their capital development projects. The program is managed by
FAA, which approves an airport’s application to participate and the specific projects to be
funded.




Page 14                                         GAO-03-252 Aviation and the Environment
located outside airport property. According to FAA, DOT’s Congestion
Mitigation and Air Quality grant program can be used to finance emission
mitigation projects located outside of airport property.

Some states also have emission reduction assistance programs that are
available to airports. The California Environmental Protection Agency
developed the Carl Moyer Program, which is an incentive-based program
that covers the incremental cost of purchasing airport vehicles with
cleaner engines, including ground support equipment at airports. The
program taps into available new environmental technologies to help the
state advance clean air goals. It provides funds to private companies or
public agencies to offset the incremental cost of purchasing the cleaner
engines. The Texas Natural Resource Conservation Commission also
established incentive funds for emission reduction efforts, similar to
California’s program. As in California, the funds are not specifically
designated for emission reductions at airports, but air carriers that are not
participating in the agreement with the Commission to voluntarily reduce
ground support equipment emissions can receive grants to convert their
ground support equipment. Airlines that are part of the voluntary
agreement would not be eligible for the incentive funds.

Some airport operators we spoke with would like EPA to set up a process
in which airports could obtain “credit” for the amount of emissions
reduced by their voluntary efforts; the credits can be “banked” by the
airport to use at a future date to offset expected increases in emissions or
they can be sold to other nonairport entities in the region that are required
to offset emissions. The airport operators also indicated that having such a
program encourages airport sponsors to undertake efforts to reduce
emissions. Such an emission credit program is available in Washington
State. Airports there can implement emission reduction efforts and obtain
emission credits, which they can save and use to offset increased
emissions from future expansion projects. Thus far, such a system has
been adopted at one location, Seattle–Tacoma International Airport, which
worked with the local clean air agency to establish a credit program for
voluntary emission reduction actions. If airports are not allowed to save
emission credits, any voluntary reductions will lower their emission
baseline, which is used to calculate the impact of future emissions, and
limit their options for any emission reductions required to obtain approval




Page 15                                 GAO-03-252 Aviation and the Environment
for future projects.16 Because of this situation, some airport officials told
us that they have waited to initiate emission reduction efforts until the
efforts are needed to gain approval for an expansion project. EPA
encourages airports to contact their state and local air quality agencies
and negotiate emission credit agreements, as was done by Seattle-Tacoma
International Airport. However, according to FAA officials, this localized
case-by-case approach to issuing emission credit is inefficient. Instead,
FAA supports a consistent national approach that it believes would lessen
the burden on airports to obtain emission credits from their respective
states.

In 1998, FAA and EPA established a process—known as the stakeholders
group—which includes representatives from state environmental agencies,
airports, air carriers, and the aerospace industry to discuss voluntary
efforts to lower nitrogen oxides and other emissions. They established the
process because federal and industry officials told us that the current
approach to reducing emissions—uncoordinated efforts by individual
airports and states—was inefficient and possibly ineffective from a
nationwide perspective. For example, some federal officials believe the
current approach encourages airlines to move their more polluting
equipment to airports that do not require cleaner vehicles, and the aviation
industry is concerned about the impact that differing state requirements
might have on their operations. According to EPA, another reason for
establishing the process was concerns by EPA, state environmental
agencies, and environmental groups about international emissions
standards, particularly standards for nitrogen oxides.

The stakeholders group decided to focus on achieving lower aircraft
emissions through a voluntary program because this strategy offered the
potential for achieving desired goals with less effort and time than a
regulatory approach. Initially, the group’s discussions focused on emission
reduction retrofit kits, which could be applied to some existing aircraft
engines, but this was found to not be technically feasible. However, as the
process evolved, the stakeholders expanded the focus to evaluating
various emission reduction strategies for aircraft and ground support
equipment. According to participants, the group is currently working to


16
  For example, if an airport produces 100 tons of nitrogen oxides per year and then
voluntarily initiates a project that reduces the amount by 10 tons, the baseline becomes
90 tons. If an expansion project then results in a 10-ton yearly increase in nitrogen oxides,
the airport might have to initiate new mitigation measures that will compensate for the
increase.




Page 16                                          GAO-03-252 Aviation and the Environment
                            establish a national voluntary agreement for reducing ground service
                            equipment emissions in the nearer term, similar to the agreement in
                            California. In the longer term, the group is considering reductions in
                            aircraft emissions through an approach known as “environmental design
                            space” that recognizes the need to balance such reductions with other
                            competing goals such as noise reduction, while assuring safety and
                            reliability. FAA also noted that airport operators used the stakeholders
                            group to highlight the need for more guidance on the process for ensuring
                            that federal actions, such as the construction of new runways, conform to
                            the appropriate state implementation plans. FAA and EPA issued guidance
                            on the process in September 2002. The group had also commissioned a
                            study to establish a baseline of aviation-related emissions and another
                            study of options for reducing them. However, the study will not be
                            completed because of resource constraints, according to participants.

                            FAA noted that the progress of the stakeholders group has been impeded
                            by the impact of the events of September 11, 2001, on the airlines and the
                            complex nature of addressing all stakeholders’ viewpoints to achieve
                            consensus on a framework that can be applied nationally. The activities of
                            the group were suspended after September 11, but resumed in May 2002.
                            According to one member of the group, many participants have been
                            frustrated by the group’s slow progress, but they hope to define a
                            nationwide program to reduce emissions from ground service equipment
                            in 2003 and continue discussion of aircraft emission reduction options.
                            However, the group has not defined specific objectives or established time
                            frames for achieving its goal of reducing aviation-related emissions.
                            Furthermore, the group’s activities may be limited by the financial
                            situation of participating air carriers.


New Air Quality Standards   In late 2003, EPA plans to begin implementing a more stringent standard
Will Pose a Challenge to    for ozone emissions, which could require more sources, including airports,
Some States and Airports    to tighten controls on nitrogen oxides and some types of volatile organic
                            compound emissions, which contribute to ozone formation. The new
                            standard calls for concentrations of ozone not to exceed .08 parts per
                            million over 8-hour blocks of time; the current standard requires
                            concentrations not to exceed .12 parts per million over 1-hour blocks of
                            time. Some state air quality officials that we spoke to believe that the
                            continued growth of aviation-related ozone precursor emissions, coupled
                            with such emissions from other sources, may affect their ability to meet to
                            the new standard.




                            Page 17                                GAO-03-252 Aviation and the Environment
                       The implementation of the 8-hour standard for ozone could have
                       significant implications for airports. Currently, 26 major commercial
                       airports are located in nonattainment areas for ozone. EPA has yet to
                       designate and classify which areas will not be in attainment with the 8-
                       hour standard. However, the agency estimates that under the 8-hour
                       standard, areas containing 12 additional airports could be designated as
                       nonattainment areas. Airports in these areas could be constrained in their
                       ability to initiate development projects if they did not comply with the
                       state implementation plans. EPA, however, believes that the new 8-hour
                       standard provides an opportunity for the airports and the states that have
                       not addressed airport emissions in their state implementation plans to
                       identify airport emission growth rates when new plans are developed
                       under the 8-hour standard.17

                       Among the 13 state air quality officials we surveyed, 5 expect that aviation
                       emissions will somewhat or moderately hinder their state’s ability to
                       demonstrate compliance with EPA’s new 8-hour ozone emission standard,
                       and 3 stated that aviation emissions will greatly hinder their ability to
                       comply.18 Some of these officials also said they are uncertain how their
                       state will meet the new standards. Because the new 8-hour standard is
                       more stringent, the states will need to develop more rigorous and
                       innovative control measures for all sources and may have to rely on the
                       federal government to reduce emissions from sources over which the state
                       does not have jurisdiction, such as aircraft engines.


                       Other countries use many of the same measures to reduce emissions at
Two Countries Have     airports as the United States and, in addition, two countries have imposed
Introduced Emission-   landing fees based on the amount of nitrogen oxides emissions produced
                       by aircraft. Emission-based landing fees and other market-based methods
Based Fees             are currently being studied by ICAO and the former have been
                       implemented in Switzerland and Sweden.19 Emission-based landing fees,


                       17
                         In September 2002, FAA and EPA issued guidance for airports developing early emissions
                       reduction programs.
                       18
                        The 13 states encompass all 26 of the top 50 busiest commercial airports located in areas
                       designated as not in attainment for ozone.
                       19
                         Market-based options are rewards or inducements to reduce emissions. They can be in
                       the form of charges, emission credit-trading regimes, and voluntary measures. According to
                       ICAO, market-based measures are policy tools that are designed to achieve environmental
                       goals at a lower cost and in a more flexible manner than traditional emission reduction
                       measures.




                       Page 18                                        GAO-03-252 Aviation and the Environment
although considered for Boston Logan International Airport, have not been
implemented at any U.S. airports and many in the U.S. aviation community
question their effectiveness.

ICAO established a working group to identify and evaluate the potential
role of market-based options, including emission charges, fuel taxes, and
emission-trading regimes,20 in reducing aviation-related emissions. Thus
far, the working group has concentrated on carbon dioxide emissions and
has concluded that the aviation sector’s participation in an emission-
trading system would be a cost-effective measure to reduce carbon
dioxide in the long term. The ICAO Assembly, the organization’s highest
body, has endorsed the development of an open emission-trading system
for international aviation and has instructed its Committee on Aviation
Environmental Protection to develop guidelines for open emission trading.
The ICAO committee has also been studying emission charges or taxes as
well as evaluating voluntary programs to reduce emissions. ICAO’s current
policy, adopted in 1996, recommends that emission-based fees be in the
form of charges rather than taxes and that the funds collected should be
applied to mitigating the impact of aircraft engine emissions.

Switzerland was the first country to implement a market-based system for
reducing aviation-related nitrogen oxides and volatile organic compound
emissions. In 1995, the Swiss federal government enacted legislation that
allowed airports to impose emission charges on aircraft. In September
1997, the Zurich airport used this authority to establish emission-based
landing fees as an incentive for air carriers to reduce emissions from
aircraft using the airport. The use of emission-based landing fees has
expanded to other airports in Switzerland and Sweden. The Geneva,
Switzerland, airport implemented an emission-based landing fee similar to
the fee scheme used in the Zurich airport in November 1998. Several
Swedish airports also implemented emission fees after the Swedish Civil
Aviation Administration approved such charges in January 1998. Similar to
the system at Zurich airport, the Swedish airports reduced the landing




20
  Emissions trading is a market based approach to reducing emissions. As practiced in the
United States, a “cap” or limit is set on the amount of emissions allowed from regulated
sources, such as power plants. The cap is set lower than historical emissions to cause
reductions. Sources are then given an allowance, which authorizes them to emit a fixed
amount of a pollutant. Sources whose emissions are lower than their allowance, can sell
the remainder of their allowance on the open market to sources that have exceeded their
allowance.




Page 19                                        GAO-03-252 Aviation and the Environment
charges so that income from emission charges is not considered an
additional source of revenue.

The establishment of emission-based landing fees in Switzerland and
Sweden has affected the operations of airlines with frequent flights to
airports in these countries. According to a representative of a jet engine
manufacturer, a Swiss airline purchased a number of new aircraft
equipped with engines designed to emit lower amounts of nitrogen oxides.
The representative said that the airline wanted the engines in order to
reduce its landing fees at Swiss airports. However, the airline filed for
bankruptcy in 2001 and has ceased operations. Only a few other airlines
have expressed interest in equipping their new aircraft with engines that
emit less nitrogen oxides because they are more expensive and less fuel-
efficient and have higher operating costs. As of December 2002, no other
airlines had purchased such engines.

No conclusive studies on the effectiveness of these emission-based landing
fees have been completed. According to the Zurich Airport Authority,
results of the emission-based landing fee can be shown only in the long
term, making it difficult to quantify whether emissions such as nitrogen
oxides or volatile organic compounds have been reduced. (FAA officials
stated that the effects of emission-based fees can be estimated using
existing models. For example, a 2001 ICAO working paper on market-
based options for reducing carbon dioxide emissions found that enroute
emissions charges would be insufficient to meet reduction targets.)
Nevertheless, an aviation expert said that the emission-based landing fees
have caused airlines to begin considering the cost of nitrogen oxides and
volatile organic compound emissions as part of their business decisions.

Emission-based landing fees have not been introduced at any U.S. airports.
Boston Logan International Airport considered implementing such fees to
reduce emissions, but a 2001 study commissioned by the Massachusetts
Port Authority, which operates the airport, determined them to be
ineffective.21 The study found that emission-based landing fees would be a
small portion of commercial air carriers’ operating expenses and would be
unlikely to affect their operational, purchasing, or leasing behavior
substantially enough for them to consider using lower nitrogen-oxides-
emitting aircraft and engines. Thus, the study concluded, the emission-



21
 Massachusetts Port Authority, Air Quality Initiative for Boston Logan International
Airport (March 2001).




Page 20                                      GAO-03-252 Aviation and the Environment
                           based landing fees would not significantly induce commercial airlines to
                           use aircraft engines emitting lower levels of nitrogen oxides.


                           Although research and development efforts by NASA and aircraft and
Improvements in            engine manufacturers have led to engine and airframe improvements that
Aircraft and Engine        have increased fuel efficiency and lowered carbon dioxide and
                           hydrocarbon emissions, trade-offs among several factors, including engine
Design Have Reduced        performance, have also resulted in increased nitrogen oxides emissions.
Many Aircraft              Our analysis of data on aircraft emissions during landings and takeoffs
                           indicates that the newest generation of aircraft engines, while meeting
Emissions, but             international standards, can produce considerably more nitrogen oxides
Nitrogen Oxides            emissions than the older versions they are replacing. Engine options for
Emissions are              some aircraft are now being introduced that reduce nitrogen oxides
                           emissions. Additionally, NASA has ongoing research into technologies that
Increasing                 could reduce nitrogen oxides emissions from jet engines to well below
                           current standards. However, aviation industry representatives are unsure
                           whether the technologies will ever be developed to the point where they
                           can be incorporated into future production engines because of
                           uncertainties about funding and other factors. Given the long lifespan of
                           aircraft, even if the technologies are developed, it could be decades before
                           enough airplanes are replaced to have a measurable effect on reducing
                           nitrogen oxides. As a result, both the environmental and aviation
                           communities have expressed concerns that emissions from aircraft,
                           particularly nitrogen oxides, need to be further reduced.


Improvements in Aircraft   Improvements in jet engine design have led to increases in fuel efficiency
and Engines Have Reduced   and reductions in most emissions, particularly emissions from aircraft
Fuel Consumption and       flying at cruise altitudes. Historically, the improvements in fuel
                           consumption for new aircraft designs have averaged about 1 percent per
Most Emissions             year. The aviation industry and NASA, which are developing fuel reduction
                           technologies, expect this rate to continue for the next two decades. Air
                           carriers’ desire to control fuel costs provided the impetus for these efforts.
                           (Appendix VI provides a brief overview of fuel reduction technologies.)

                           According to aircraft design experts, fuel consumption is the single biggest
                           factor affecting the amount of most aircraft emissions. Table 1 shows the
                           amount of emissions produced by a typical aircraft turbine engine during
                           cruising operations for each 1,000 grams of fuel burned.




                           Page 21                                 GAO-03-252 Aviation and the Environment
                             Table 1: Aircraft Turbine Engine Emission Amounts during Cruising Per 1000
                             Grams of Fuel Burned

                              Type of emissions                                         Amount of emissions (in grams)
                              Carbon dioxide                                                                      3,200
                              Water                                                                               1,200
                              Nitrogen oxides (as nitrogen dioxide)                                                  15
                              Carbon monoxide                                                                         1
                              Sulfur oxides                                                                           1
                              Hydrocarbons (as methane)                                                            0.20
                              Soot (as carbon)                                                                     0.02
                             Source: National Research Council.

                             Note: For Greener Skies, Reducing Environmental Impacts of Aviation (Washington, D.C.: National
                             Academy Press, 2002).


                             According to aviation experts, new aircraft designs are reducing carbon
                             dioxide emissions by about 1 percent per year—the same rate at which
                             fuel consumption is being reduced. ICAO expects this carbon dioxide and
                             fuel reduction trend to continue for the next 20 years. Carbon monoxide
                             and hydrocarbon cruise emissions are declining even faster than the fuel
                             reduction rates. These emissions, which are formed when a portion of the
                             fuel is only partially combusted, are much easier to minimize with the
                             hotter engine temperatures of the new more fuel-efficient engine designs.


New Aircraft Designs         A byproduct of the improvements in jet engine design has been an
Produce Significantly More   increase in nitrogen oxides emissions during landings and takeoffs and
Nitrogen Oxides during       while cruising, according to aviation industry experts. The new engine
                             designs are capable of operating at higher temperatures and producing
Landings and Takeoffs        more power with greater fuel efficiency and lower carbon monoxide
                             emissions. However, as engine-operating temperatures increase so do
                             nitrogen oxides emissions. This phenomenon is most pronounced during
                             landings and takeoffs, when engine power settings are at their highest. It is
                             during the landing/takeoff cycle that nitrogen oxides emissions have the
                             biggest impact on local air quality.

                             Our analysis of aircraft landing/takeoff emissions shows that newer
                             aircraft produce considerably more nitrogen oxides than older models. We
                             identified examples of aircraft models and engines introduced in the last
                             5 years and compared their emissions with emissions from older aircraft




                             Page 22                                           GAO-03-252 Aviation and the Environment
they might replace.22 We found, for example, that although the newer
Boeing 737 series aircraft are more fuel-efficient, are capable of flying
longer distances (or with more weight), emit less carbon monoxide and
hydrocarbons, and produce less takeoff noise than their predecessors,
they also produce 47 percent more nitrogen oxides during landing/takeoff
(see table 2).23

Table 2: Comparison of Emissions during Landing/Takeoff for Older and the Newest
Model Boeing 737s

                                 Average emission (in pounds) per
                                          landing/takeoff
 Emission                       Older Boeing 737     Newest Boeing 737                    Change
 Nitrogen oxides                             12.1                 17.8               47% increase
 Carbon monoxide                             16.8                 10.7              37% decrease
 Hydrocarbons                                 1.2                  1.1              10% decrease
Source: GAO.

Note: Landing and takeoff data for U.S. aircraft in 2001 obtained from AvSoft; emissions calculated
using FAA’s Emissions and Dispersion Modeling System, version 4.01. See appendix VII for
additional information on our emission calculations and Boeing 737 models and engines.


Significantly higher emissions of nitrogen oxides during landing/takeoff
for the aircraft introduced in the last 5 years also occur in the largest
aircraft. For example, the Boeing 777, the newest of the large jets, emits
significantly more nitrogen oxides than comparable older aircraft. Table 3
compares a passenger model Boeing 747-400 with the Boeing 777 model
and engines that it is most comparable to in seating capacity and range.
Even before we adjusted for the greater seating capacity of the larger
Boeing 747-400, we found that the most comparable Boeing 777—the
200ER model—produces 34 percent more nitrogen oxides emissions, even


22
  To the extent possible, we compared aircraft that can be used interchangeably to fulfill
the same mission (same number of passengers, same range). In instances where aircraft fly
the same routes but have different seating capacity, we made comparisons on a per seat
basis. The most straightforward comparison of newest versus older aircraft emissions
involves the various Boeing 737 models. This family of medium-sized jets made
22.6 percent of all landings and takeoffs in the 2001 U.S. aircraft fleet. Furthermore, all
models in this family have been updated in the last 5 years with improved airframes and
engines.
23
 The U.S. 2001 commercial fleet included 988 older Boeing 737s. They accounted for
17.6 percent of this fleet’s landings and takeoffs and 13.4 percent of this fleet’s nitrogen
oxides emissions during landing and takeoffs. The U.S. 2001 commercial fleet included
449 newer Boeing 737s. They accounted for 5.0 percent of this fleet’s landings and takeoffs
and 5.5 percent of this fleet’s nitrogen oxides emissions during landings and takeoffs.




Page 23                                              GAO-03-252 Aviation and the Environment
though ICAO data shows that the Boeing 777 is quieter and more fuel-
efficient than the older aircraft it is replacing. For example, on a per seat
basis, the Boeing 777 can be as much as 30 percent more fuel-efficient than
older model Boeing 747s.

Table 3: Comparison of Boeing 747 and 777 Emissions on a Per Aircraft Basis

                        Emission (in pounds) per aircraft during
                                    landing/takeoff
 Emission                Boeing 747-400     Boeing B777-200ER                             Change
 Nitrogen oxides                    103.5                   124.2             20 percent increase
 Carbon monoxide                     47.7                    30.4            36 percent decrease
 Hydrocarbons                         4.1                     2.4            41 percent decrease
Source: GAO.

Notes: Landing and takeoff data for U.S. aircraft in 2001 obtained from AvSoft; emissions calculated
using FAA’s Emissions and Dispersion Modeling System, version 4.01. See appendix VII for
additional information on our emission calculations and details about these aircraft and their
contribution to the 2001 U.S. commercial fleet totals.

The Boeing B777-200ER data is the weighted average (based on 2001 landings and takeoffs) for
three different engines. The nitrogen oxides and other emission characteristics of these engines vary
significantly.


As shown in table 4, the percentage increase in nitrogen oxides during
landing/takeoff is 57 percent when the two aircraft are compared on a per
seat basis (the amount of emissions divided by the number of seats on the
aircraft).

Table 4: Comparison of Boeing 747 and 777 Emissions on a Per Seat Basis

                             Emission (in pounds) per seat during
                                        landing/takeoff
 Emission                     Boeing 747-400 Boeing B777-200ER                             Change
 Nitrogen oxides                         0.287                0.451             57 percent increase
 Carbon monoxide                         0.132                0.110            16 percent decrease
 Hydrocarbons                            0.011                0.009            20 percent decrease
Source: GAO.

Note: Landing and takeoff data for U.S. aircraft in 2001 obtained from AvSoft; emissions calculated
using FAA’s Emissions and Dispersion Modeling System, version 4.01. GAO analysis of AvSoft 2001
landing and takeoff data for U.S. aircraft.


EPA and FAA regulate nitrogen oxides emissions and other emissions for
U.S. commercial aircraft by requiring engine designs to meet ICAO
standards for these emissions. Prior to production, all new engine designs
are tested to determine the amount of nitrogen oxides and other emission




Page 24                                              GAO-03-252 Aviation and the Environment
characteristics.24 Only engines that meet the standards are certified for
production. ICAO standards for nitrogen oxides were first adopted in 1981
and more stringent standards were adopted in 1993 (20 percent more
stringent, effective 1996) and again in 1998 (16 percent more stringent,
effective 2004). ICAO working groups are assessing whether or not the
standards for nitrogen oxides emissions should be made more stringent
than the standards that will take effect in 2004. Options being considered
could make the standards between 5 percent and 30 percent more
stringent between 2008 and 2012.

Under ICAO standards, newly designed engines and modified versions of
older designs are allowed to produce significantly more nitrogen oxides
than their predecessors. This is because the ICAO standards recognize that
nitrogen oxides emissions are a function of engine power capability and
operating pressure. Therefore, the standards allow for higher nitrogen
oxides emissions for engines that (1) operate at higher-pressure ratios,
which increase their fuel efficiency and (2) produce more power. For
example, the most common updated Boeing 737-700 aircraft model and
engine produces 41 percent more nitrogen oxides during landing/takeoff
than the most common older version it is replacing (see table 5). Both
engines will meet the new ICAO standard, which will go into effect in 2004
(the old engine betters the standard by about 15 percent, the new one by
about 10 percent). A lower nitrogen oxides producing engine is available
for the Boeing 737-700. This engine produces 18.5 percent more nitrogen
oxides than the older Boeing 737-700 that it is most comparable to in
power and versatility.25 However, this engine is less common in the fleet
that then the more powerful one that offers more aircraft versatility. The
database we use shows that in the U.S. fleet there were 8 Boeing 737-700s
with the lower nitrogen oxides emitting engines and 118 with the more
powerful engines.




24
  Almost all that is known about the emission characteristics of a particular engine comes
from these certification tests, which cover four modes of the landing/takeoff cycle (taxi
in/taxi out, takeoff, climb out, and approach). Landing/takeoff emissions are derived from
computer models that combine the engine certification emission data with characteristics
of specific aircraft.
25
 The ICAO Engine Exhaust Emissions Data Bank lists the power of the CFM56 3B-1 engine
(used on the Boeing 737-700) at 89.4 kiloNewtons. The CFM56 7B-20 (used on the Boeing
737-700) is rated at 91.6 kiloNewtons.




Page 25                                        GAO-03-252 Aviation and the Environment
Table 5: Comparison of Power, Engine Operating Pressures, and Nitrogen Oxides
Emissions for Two Models of Boeing 737s

                                                      Older model                  Newest model
 Characteristic                                           B737-300                       B737-700
 Engine variant                                       CFM56 3B-1                    CFM56 7B-22
 Power (thrust) per engine                          89 kiloNewtons                101 kiloNewtons
 Engine operating pressure ratio                              22.4                          24.41
 Landing/takeoff nitrogen oxides emissions           10.72 pounds                   15.08 pounds
Source: GAO.

Note: Landing and takeoff data for U.S. aircraft in 2001 obtained from AvSoft; emissions calculated
using FAA’s Emissions and Dispersion Modeling System, version 4.01. See appendix VII for
additional information on our calculations and details about these aircraft.


There is an ongoing debate between the aviation and environmental
communities over the best method for developing nitrogen oxides
certification standards. Some in the aviation community want to maintain
the current system under which the standards are made more stringent
only when the engine manufacturers have produced engines that meet the
new standards and new standards only apply to newly certified engines.26
(An industry official identified only two older types of engines that would
not meet the more stringent 2004 nitrogen oxides standards.) Officials for
the aviation industry said that it would be inadvisable to force more
aggressive nitrogen oxides standards because new engine development
programs are already complex and have many business and schedule
risks. These officials added that the environmental regulatory process
lacks cost-benefits data to defend a more aggressive approach that could
result in extreme financial harm for engine and aircraft manufacturers if
the approach delayed a new program. Further, some believe that if
reductions in nitrogen oxides were to become a higher priority, it would
be better to have market-based incentives that reward lower nitrogen
oxides emissions than have aggressive and rigid pass/fail regulatory
barriers.

Moreover, some federal, state, and local environmental officials believe
more incentives are needed to reduce aircraft nitrogen oxides emissions
beyond the ICAO certification standards that are to take effect in 2004.
They say that the current system gives little value to reducing nitrogen
oxides in the many trade-offs among emissions, fuel-consumption, and


26
 According to FAA, this approach has produced an aircraft fleet that is about 65 percent
more fuel efficient than in 1970 and aircraft engines with a high safety record.




Page 26                                              GAO-03-252 Aviation and the Environment
                             other factors made during engine design. They reason that if there were
                             more incentives to reduce nitrogen oxides emissions beyond the
                             certification requirements, these incentives would accelerate innovations
                             that minimize degradations in other engine performance characteristics
                             such as fuel efficiency.

                             While NASA and engine manufacturers have made continuous
                             improvements for decades in technologies that have improved fuel
                             efficiency, decreased noise, and decreased all emissions including
                             nitrogen oxides, the design of the newest generation of engines has
                             resulted in trade-offs that favor fuel efficiency and increase nitrogen
                             oxides. Two engine manufacturers have responded to this problem by
                             developing options for several new engines that reduce nitrogen oxides.
                             (General Electric has developed a “dual annular combustor” technology
                             for one of its CFM56 engines and Pratt Whitney has developed a
                             “Technology for Affordable Low NOx” [TALON] for some of its engines.
                             This TALON technology is being used on some aircraft in the U.S. fleet.)
                             According to NASA, about 100 engines using one of these technology
                             options are currently in service on passenger and cargo aircraft. According
                             to industry officials, knowledge gained from developing these options is
                             contributing to ongoing nitrogen oxides reduction research.

Potential Success of         NASA, in association with jet engine manufacturers and the academic
Efforts to Reduce Aircraft   community, is working on several technologies to reduce nitrogen oxides
Nitrogen Oxides Emissions    emissions, although it is unclear if they can be introduced on commercial
                             aircraft in the foreseeable future. If successfully developed and
Uncertain                    implemented, these technologies could significantly lower the emission of
                             nitrogen oxides during landing and takeoff in new aircraft in stages over
                             the next 30 years. However, the development of more fuel-efficient engines
                             by NASA and the engine manufacturers, which are resulting in higher
                             nitrogen oxides emissions,27 and the lack of economic incentives for
                             airlines to support efforts to reduce nitrogen oxides emissions make the
                             possibility of reaching these goals uncertain. In the last several years,
                             increases in nitrogen oxides emissions from the more fuel-efficient
                             engines have outpaced improvements made to reduce these emissions.
                             Appendix VI provides more information on research to reduce nitrogen
                             oxides emissions.



                             27
                              The new fuel-efficient engines are operating at increasingly higher engine operating
                             pressures. The nitrogen oxides emissions standards allow for increasing emissions as this
                             pressure increases.




                             Page 27                                        GAO-03-252 Aviation and the Environment
Adding to the uncertainty of introducing technologies to reduce nitrogen
oxides is the limited federal funding for this research effort. NASA officials
told us that in the past they developed their research to the full engine test
level before engine manufacturers would take over responsibility for
integrating the improvements into production-ready engines. However,
budget cuts made in their emission research programs beginning in fiscal
year 2000 have resulted in them ending their research at the engine
component level below full engine testing. Figure 2 shows the funding for
this program.

Figure 2: NASA’s Planned Funding for Nitrogen Oxides Research




Note: GAO analysis of information from NASA. Funding amounts are for the Ultra Efficient Engine
Technology Program.


Industry officials and aviation experts agree on the importance of NASA’s
research and that NASA is focusing on the right mix of near-term and long-
term technologies, but are critical of the amount of funding dedicated to
nitrogen oxides reduction research. NASA’s research to reduce nitrogen
oxides is a component of its Ultra Efficient Engine Technology Program.
The goal of this program is to develop technologies that will enable U.S.
manufacturers to compete in the global marketplace for new commercial
gas turbine engines. The current program is funded at $50 million per year.
Industry representatives stated that shrinking budgets have made it
difficult for NASA to maintain a level of effort at a critical mass for each


Page 28                                            GAO-03-252 Aviation and the Environment
                          project within the Ultra Efficient Engine Technology Program.
                          Furthermore, they added that engine manufacturers could not afford to
                          work with immature technology when they are engaged in new engine
                          development projects. This is because new engine developments are tied
                          into projects with the airlines, and the engines must meet tight cost,
                          schedule, and performance goals if they are to win market share.

                          The Ultra Efficient Engine Technology Program is a scaled-back version of
                          a larger aeronautical research program that was terminated in fiscal year
                          2000. NASA officials said that budget cuts have reduced research in the
                          current program by about 40 percent from the previous program. In the
                          previous program, research was typically developed to the point where the
                          technology was integrated into the full engine system. In the current
                          program, funding is only available to incorporate the technology into
                          engine components. The National Research Council has concluded that
                          the current funding level jeopardizes achieving program results and does
                          not carry the research far enough for the engine manufacturing industry to
                          readily adopt it.28

                          As a result of the uncertainties surrounding emission reduction technology
                          research, it is unclear when new production aircraft will, in the aggregate,
                          start lowering landing/takeoff nitrogen oxides emissions on a per seat
                          basis during the landing/takeoff cycle. Because of the 30-year projected
                          life of new commercial aircraft, it could take decades before future new
                          aircraft can contribute to nitrogen oxides reductions.


Concerns Over Emissions   Both the environmental and aviation communities have voiced concerns
from Aircraft             about the need to better control the growth of aircraft emissions,
                          particularly nitrogen oxides. Air quality officials from the 13 states that
                          have airports in nonattainment areas told us that emission standards for
                          aircraft should be made more stringent for a number of reasons. For
                          example, several of those officials said that available control measures for
                          other air pollution sources have been nearly exhausted. They noted that
                          aircraft have not been as strictly regulated as other sources, such as
                          automobiles, and that reductions from aircraft may be needed in the future




                          28
                           National Research Council, For Greener Skies, Reducing Environmental Impacts of
                          Aviation (Washington, D.C.: National Academy Press, 2002).




                          Page 29                                     GAO-03-252 Aviation and the Environment
for some areas to maintain attainment of the Clean Air Act’s standards.29
Likewise, in 2002, the National Academy of Science’s National Research
Council reported that the advances that have led to increased efficiencies
in individual airplanes are not sufficient to decrease the total emissions of
the global fleet, which is increasing in response to accelerating demand.30
In the same vein, the Intergovernmental Panel on Climate Change reported
in 1999 that “although improvements in aircraft and engine technology and
in the efficiency of the air traffic control system will bring environmental
benefits, these will not fully offset the effects of the increased emissions
resulting from the projected growth in aviation.”

Concerns about aircraft emissions have prompted calls for an improved
approach for controlling them. For example, the National Research
Council has recommended31 that the U.S. government carry out its
responsibilities for mitigating the environmental effect of aircraft
emissions and noise with a balanced approach that includes interagency
cooperation in close collaboration with the private sector and university
researchers. The Council emphasized that the success of this approach
requires commitment and leadership at the highest level as well as a
national strategy and plan that, among other things, coordinates research
and technology goals, budgets, and expenditures with national
environmental goals. Along the same lines, a recent industry article on the
environmental effectiveness of ICAO emission standards suggested that a
programmatic framework is required to guide the development of a
consensus on policy options for further reducing aircraft emissions.32
Among the elements of the framework would be establishing the
environmental need, the technical capability, the economic viability, and
the regulatory consistency of each option.




29
  According to FAA official, aircraft are more heavily regulated than other mobile sources
in terms of design, maintenance, and operation and have safety and noise regulations that
other mobile sources lack.
30
 National Research Council, For Greener Skies, Reducing Environmental Impacts of
Aviation (Washington, D.C.: National Academy Press, 2002).
31
 Ibid.
32
 Howard G. Aylesworth, Jr. and Peter Newton, “Qualitative Standards of the
Environmental Effectiveness of International Civil Aviation Organization Emissions
Standards and Recommended Practices,” Handbook of Airline Strategy: Public Policy,
Regulatory Issues, Challenges, and Solutions (Washington, D.C: Aviation Week, 2001).




Page 30                                        GAO-03-252 Aviation and the Environment
                         Aviation’s impact on local air quality is expected to grow as a result of
Conclusion               projected increases in air travel. In addition, more attention will be
                         focused on finding additional ways to reduce emissions from airports to
                         enable localities to meet more stringent ozone standards, which go into
                         effect in late 2003. In 1998, FAA, EPA, and industry officials established a
                         stakeholders group to develop and implement a voluntary, nationwide
                         program to reduce aviation-related nitrogen oxides emissions because
                         they found the current approach—uncoordinated efforts by individual
                         airports and states—inefficient for air carriers and potentially ineffective
                         in reducing emissions nationwide. However, the stakeholders group has
                         progressed slowly because of the complex nature of achieving consensus
                         on all issues and, thus far, has not defined specific objectives or
                         established time frames for achieving emissions reductions.

                         Despite its participation in the stakeholder group, FAA has not developed
                         a long-term strategic framework to deal with these challenges. Moreover,
                         FAA lacks a thorough study on the extent and impact of aviation
                         emissions on local air quality. Without such management tools, FAA
                         cannot assess the status or the effectiveness of its efforts to improve air
                         quality. The study on aviation emissions prepared by the
                         Intergovernmental Panel on Climate Change on aviation’s effect on the
                         global atmosphere provides a model for a study that FAA could perform to
                         develop baseline information and lay a foundation for a strategic
                         framework. Such a study could accomplish the goals of the study that the
                         stakeholders group commissioned, but never completed, as well as create
                         an opportunity for making public the substance of its deliberations and for
                         incorporating this substance in a plan for reducing emissions. Once
                         completed, such a study would provide baseline information for setting
                         goals and time frames to measure progress in reducing aviation-related
                         emissions.


                         We recommend that the Secretary, DOT, direct the Administrator of FAA,
Recommendation for       in consultation with the Administrator of EPA and Administrator of NASA,
Executive Action         to develop a strategic framework for addressing emissions from aviation-
                         related sources. In developing this framework, the Administrator should
                         coordinate with the airline industry, aircraft and engine manufacturers,
                         airports, and the states with airports in areas not in attainment of air
                         quality standards. Among the issues that the framework should address
                         are

                     •   the need for baseline information on the extent and impact of aviation-
                         related emissions, particularly nitrogen oxides emissions;


                         Page 31                                 GAO-03-252 Aviation and the Environment
                  •   the interrelationship among emissions and between emissions and noise;
                  •   options for reducing aviation-related emissions, including the feasibility,
                      cost, and emission reducing potential of these options;
                  •   goals and time frames for achieving any needed emission reductions;
                  •   the roles of NASA, other government agencies, and the aviation industry in
                      developing and implementing programs for achieving needed emission
                      reductions; and
                  •   coordination of emission reduction proposals with members of ICAO.

                      Upon its completion, the Administrator, FAA, should communicate the
                      plan to the appropriate congressional committees and report to them on
                      its implementation on a regular basis.

                      We provided a draft of this report to the Department of Transportation, the
Agency Comments       Environmental Protection Agency, and the National Aeronautics and
                      Space Administration for review and comment. FAA’s Director, Office of
                      Environment and Energy, and senior managers in EPA’s Office of Air and
                      Radiation provided oral comments and NASA’s Deputy Director provided
                      written comments. (See appendix VIII.) The three agencies generally
                      concurred with our findings and recommendation and provided technical
                      corrections, which we incorporated as appropriate. In addition, FAA
                      indicated that our report provides a helpful overview on the aviation
                      emissions issue from the perspective of multiple stakeholders dealing with
                      this important issue. FAA also indicated that it is providing heightened
                      attention to aviation emissions through multiple efforts including
                      improving data and modeling, working with the international community
                      on improved standards, and considering alternative approaches to
                      encourage reductions in aviation-related, ground-based and aircraft
                      emissions.


                      As agreed with your office, unless you publicly announce the contents of
                      this report earlier, we plan no further distribution until 5 days from the
                      report date. At that time, we will send copies of this report to interested
                      congressional committees; the Secretary of Transportation; the
                      Administrator, FAA; the Administrator, EPA; and the Administrator,
                      NASA. We also will make copies available to others upon request. In




                      Page 32                                 GAO-03-252 Aviation and the Environment
addition, the report will be available at no charge on the GAO Web site at
http://www.gao.gov. Please call me at (202) 512-3650 if you or your staff
have any questions concerning this report. Major contributors to this
report are listed in appendix IX.

Sincerely yours,




Gerald L. Dillingham
Director, Physical Infrastructure Issues




Page 33                                GAO-03-252 Aviation and the Environment
              Appendix I: Objectives, Scope, and
Appendix I: Objectives, Scope, and
              Methodology



Methodology

              The Chairman of the Subcommittee on Aviation, House Committee on
              Transportation and Infrastructure asked us to provide information on the
              nature and scope of aviation’s impact on air quality and the opportunities
              that exist to reduce emissions from aviation activities. Specifically, our
              research focused on (1) what efforts are being undertaken to reduce
              emissions from airport activities and what the outcomes are of these
              efforts, (2) what additional efforts are being undertaken by other countries
              to reduce aviation-related emissions, and (3) how improvements in aircraft
              and engine design have affected aircraft emissions.

              To address the three questions, we interviewed and collected material
              from federal officials at the Federal Aviation Administration (FAA),
              Environmental Protection Agency (EPA), and National Aeronautics and
              Space Administration (NASA). We also interviewed and collected
              information from representatives of aviation associations, airlines, and
              aircraft manufacturers. We also interviewed officials from airports, state
              and local governments, and nongovernmental organizations. In addition,
              we reviewed our previous studies and those of EPA, the Natural
              Resources Defense Council, the International Panel on Climate Control,
              and other aviation-related environmental studies.

              To address the first research question, we identified the nation’s 50 busiest
              commercial service airports and determined that 43 of these airports are
              located in areas designated as nonattainment or maintenance with respect
              to requirements of the Clean Air Act. We reviewed and summarized
              environmental review documents submitted from 1997 through 2001 for
              the 43 airports to identify the nature of emissions from aviation activities
              and efforts to mitigate them. We also reviewed applicable sections of state
              implementation plans for the 13 states in which the 43 airports are located
              to identify emission-related sources and determine the nature of mitigation
              measures being undertaken. We also conducted comprehensive computer
              literature searches to identify the environmental effects of airport
              operations.

              To also address the first research question and to provide information on
              the roles and responsibilities of states in relation to aviation-related
              emissions, we identified 13 states with airports located in air quality
              problem areas and conducted a telephone survey with state air quality
              authorities in these areas to obtain information on oversight/regulatory
              responsibilities for airport activities. We selected the states by first
              identifying the top 50 busiest commercial service airports on the basis of
              the number of air carrier landings and takeoffs in fiscal year 2001. In those
              states, 26 airports were identified as being located in areas designated as


              Page 34                                 GAO-03-252 Aviation and the Environment
Appendix I: Objectives, Scope, and
Methodology




nonattainment for ozone. The 26 airports are located in the following 13
states: Arizona, California, Georgia, Kentucky, Maryland, Massachusetts,
Missouri, New Jersey, New York, Pennsylvania, Texas, Illinois, and
Virginia. We reviewed applicable sections of the Clean Air Act, the
National Environmental Policy Act, states’ air quality laws, and
International Civil Aviation Organization (ICAO) policies that defined air
emissions standards applicable to aviation-related activities and agencies’
role and responsibilities for administering them.

For the first research question, we also selected seven airports for case
studies—Los Angeles International, Boston Logan International,
Sacramento International, Dallas/Fort Worth International, Chicago
O’Hare International, George Bush International/Houston, and Atlanta
Hartsfield airports. We selected these airports on the basis of passenger
traffic, air quality status, and initiatives undertaken to deal with airport-
related emissions. At each location, we interviewed and gathered data
from officials representing FAA and EPA regional offices, airports, state
and local governments, and nongovernmental organizations on efforts to
reduce emissions.

To address the second research question, we identified international
efforts to reduce aviation-related emissions through our interviews with
FAA, Department of State, ICAO, airport, airline, and nongovernmental
agency officials. We conducted comprehensive computer literature
searches to identify other international airports and to gather information
on the efforts being undertaken by these airports to reduce aviation-
related emissions. Our searches identified aviation reduction programs at
European airports, including Switzerland and Sweden. We reviewed
materials from Swiss and Swedish federal civil aviation officials on these
efforts. We also reviewed proposed European Unions policies on reducing
aviation-related emissions.

Finally, to address the third research question, we interviewed jet engine
manufacturers, NASA researchers, and a university researcher to obtain
information on efforts to reduce aircraft emissions. In addition, we
calculated the landing and takeoff emissions for every aircraft model and
engine combination in the U.S. 2001 commercial fleet for which data were
available. Next, we looked for emission trends by identifying instances in
which new model/engine combinations had been introduced in the last 5
years. We then compared the landing/takeoff emission characteristics of
these newer aircraft with the emissions of the older aircraft they were
most likely to replace. We identified examples of emissions trends for new
aircraft. We did not perform a complete analysis of all trends.


Page 35                                  GAO-03-252 Aviation and the Environment
    Appendix I: Objectives, Scope, and
    Methodology




    In performing this analysis, we obtained the following information on
    every aircraft in the U.S. commercial aircraft fleet:

•   specific model and engine,
•   year 2001 landing/takeoff counts,
•   aircraft age, and
•   seating capacity.

    This information came from AvSoft, a company that specializes in detailed
    data on commercial aircraft. We summarized this information for each
    specific model and engine combination. We then calculated the
    landing/takeoff emissions for each of these combinations using the
    Emissions and Dispersion Modeling System (EDMS), version 4.01 software
    developed by FAA for this purpose.

    EDMS software calculates landing/takeoff emissions for four major
    criteria pollutants: carbon monoxide, volatile organic compounds,
    nitrogen oxides, and sulfur dioxides. The calculations take into account
    characteristics of specific aircraft model/engine combinations as well as
    airport-specific variations in the landing/takeoff cycle. We calculated the
    emissions for a representative “generic” airport using EDMS default
    values. Key values used in our EDMS calculations were

•   emission ceiling height: below 3,000 feet;
•   taxi-time: 15 minutes;1 and
•   takeoff weight: EDMS default value.

    To determine the reliability of the software and data we used, we reviewed
    FAA’s and AvSoft’s quality controls, customer feedback information, and
    self-assessments. A weakness AvSoft identified with the data we used was
    a tendency to undercount the landings/takeoffs for smaller aircraft
    (aircraft with 70 seats or less). In addition, the EDMS software does not
    have complete information on some of the less common aircraft models
    and engines. This weakness, however, did not affect the trends we
    identified because of the limited use of these models and engines. On the
    basis of our experience working with the data and the software, we
    determined that the vendors were providing reliable products for the



    1
     ICAO’s analyses use 26 minutes as the default value for taxi-time. Our analysis of
    information provided by FAA indicated that 15 minutes was a more appropriate value for
    the large number of U.S. airports in our analysis.




    Page 36                                       GAO-03-252 Aviation and the Environment
Appendix I: Objectives, Scope, and
Methodology




purposes for which we used them and that additional data and software
reliability assessments were not needed to support our conclusions.

During the review, the following aviation experts reviewed our methods
and report drafts for accuracy and balance: John Paul Clarke of the
Massachusetts Institute of Technology; Mary Vigilante of Synergy
Consulting, Inc.; and Ian Waitz of the Massachusetts Institute of
Technology.




Page 37                              GAO-03-252 Aviation and the Environment
                   Appendix II: Types, Amounts, and Impact of
Appendix II: Types, Amounts, and Impact of
                   Emissions from Aviation-related Sources



Emissions from Aviation-related Sources

                   Most emissions associated with aviation come from burning fossil fuels
                   that power aircraft, the equipment that services them, and the vehicles
                   that transport passengers to and from airports. The primary types of
                   pollutants emitted by aircraft and airport-related sources are volatile
                   organic compounds, carbon monoxide, nitrogen oxides, particulate
                   matter, sulfur dioxide, toxic substances such as benzene and
                   formaldehyde, and carbon dioxide, which in the upper atmosphere is a
                   greenhouse gas that can contribute to climate change. When combined
                   with some types of volatile organic compounds in the atmosphere, carbon
                   dioxide forms ozone, which is the most significant air pollutant in many
                   urban areas as well as a greenhouse gas in the upper atmosphere.
                   Particulate matter emissions result from the incomplete combustion of
                   fuel. High-power aircraft operations, such as takeoffs and climb outs,
                   produce the highest rate of particulate matter emission due to the high fuel
                   consumption under those conditions. Sulfur dioxide is emitted when
                   sulfur in the fuel combines with oxygen during the combustion process.
                   Fuels with higher sulfur contents produce higher amounts of sulfur
                   dioxide than low-sulfur fuels. Ozone and other air pollutants can cause a
                   variety of adverse health and environmental effects.


                   Aircraft emit pollutants both at ground level as well as over a range of
Aviation-Related   altitudes. At most U.S. airports, aircraft can be a major source of air
Emissions and      pollutants. The major air pollutants from aircraft engines are nitrogen
                   oxides, carbon monoxide, sulfur dioxide, particulate matter, and volatile
Sources            organic compounds. The burning of aviation fuel also produces carbon
                   dioxide, which is not considered a pollutant in the lower atmosphere but is
                   a primary greenhouse gas responsible for climate change. During the
                   landing and takeoff cycles, and at cruising altitudes, aircraft produce
                   different levels of air pollutant emissions. Emission rates for volatile
                   organic compounds and carbon monoxide are highest when aircraft
                   engines are operating at low power, such as when idling or taxiing.
                   Conversely, nitrogen oxides emissions rise with an increasing power level
                   and combustion temperature. Thus, the highest nitrogen oxides emissions
                   occur during aircraft takeoff and climb out. In addition, aircraft have
                   mounted auxiliary power units that are sometimes used to provide
                   electricity and air conditioning while aircraft are parked at terminal gates
                   and these units emit low levels of the same pollutants as aircraft engines.
                   When flying at cruising altitudes, aircraft emissions, including carbon
                   dioxide, nitrogen oxides, and aerosols that are involved in forming
                   contrails and cirrus clouds, contribute to climate change.




                   Page 38                                      GAO-03-252 Aviation and the Environment
Appendix II: Types, Amounts, and Impact of
Emissions from Aviation-related Sources




Ground support equipment—which provide aircraft with such services as
aircraft towing, baggage handling, maintenance/repair, refueling, and food
service—is also a source of emissions at airports. This equipment is
usually owned and operated by airlines, airports, or their contractors.
According to EPA, the average age of ground support equipment is about
10 years, although some of the equipment can last more than 30 years with
periodic engine replacement. Most ground support equipment is powered
by either diesel or gasoline engines, and older engines pollute more than
newer engines. Emissions from ground support equipment include volatile
organic compounds, carbon monoxide, nitrogen oxides, and particulate
matter. At some airports, airlines and the airport operators are introducing
electric and alternative-fuel powered ground support equipment.

Emissions from passenger vehicles and trucks, referred to as ground
access vehicles, are an important consideration at airports. Heavy traffic
and congestion in and around airports result from the influx of personal
vehicles, taxis and shuttles discharging and picking up passengers, and
trucks hauling airfreight and airport supplies. Such traffic generates
significant amounts of the emissions including carbon monoxide, volatile
organic compounds, and nitrogen oxides. Several states that we surveyed
indicated that automobiles are the major source of volatile organic
compounds, carbon monoxide, particulate matter, and nitrogen oxides in
areas with air quality problems at airports. This situation has occurred
despite the fact that automobile emissions have been reduced on a per
vehicle basis by 98 percent in the past 25 years.

Other sources of emissions at airports include construction activities,
electric power generating plants, and maintenance operations. The air
pollutants emitted by these activities can include particulate matter,
nitrogen oxides, carbon monoxide, and sulfur dioxide.

The information available on the relative contribution of aviation-related
activities to total emissions in an area is limited, but it indicates that these
activities account for a small amount of air pollution and the proportion
attributed to airports is likely to grow over time. According to EPA,
aircraft, which are the only source of emissions unique to airports,
currently account for about 0.6 percent of nitrogen oxides, 0.5 percent of
carbon monoxide, and 0.4 percent of the volatile organic compounds
emitted in the United States from mobile sources.1 In cities with major


1
 Environmental Protection Agency, National Air Quality and Emissions Trends Report,
1999, EPA 454/R-01-004 (Washington, D.C.: March 2001).



Page 39                                      GAO-03-252 Aviation and the Environment
Appendix II: Types, Amounts, and Impact of
Emissions from Aviation-related Sources




airports, aircraft-related emissions could be higher or lower. In a 1999
study of 19 airports located in 10 cities,2 EPA found that the proportion of
nitrogen oxides emissions from mobile sources attributed to aircraft
ranged from 0.6 percent to 3.6 percent in 1990. EPA also found that aircraft
accounted for 0.2 percent to 2.8 percent of volatile organic compound
emissions from mobile sources in the 10 cities during the period. From
information contained in a recent study of emissions at Dallas/Fort Worth
International Airport we estimated that aircraft produced about 3 percent
of the nitrogen oxides and about 5 percent of the carbon monoxide
present in the metropolitan area.3 A 1999 study of emissions at Chicago
O’Hare International Airport found that aircraft and the airport as a whole
emitted about 1.6 percent and 2.6 percent of the total volatile organic
compound emissions, respectively, within a 10-mile radius of the airport’s
terminal area and that nonairport sources were considerably more
important to local air quality than aircraft.4 In addition, a 2001 report on an
air quality initiative for Boston Logan International Airport stated that the
airport contributed less than 1 percent of the ozone-forming nitrogen
oxides and volatile organic compound emissions in the Boston area.5

Little research has been done on how much of total area emissions (called
an emissions inventory) are attributable to ground support equipment and
airport-related road traffic, because they are categorized as nonroad and
onroad mobile sources, both of which are already accounted for in
emissions inventories. However, our analysis of the Dallas/Fort Worth
International Airport emissions inventory indicated that ground support
equipment contributed almost 3 percent of the nitrogen oxides emissions
for the area. When all airport-related emissions are added together, we




2
 ICF Consulting Group, Evaluation of Air Pollutant Emissions from Subsonic
Commercial Jet Aircraft, EPA420-R-99-013 (Washington, D.C.: April 1999). In this report,
which was prepared for EPA, the agency acknowledged that some groups, including the air
transport industry were critical of the growth projections, fleet turnover assumptions, and
emissions estimates used in the report. As a result, these groups believe the report
overstates the amount of emissions generated by aircraft.
3
Dallas/Fort Worth International Airport, Inventory of Air Emissions (July 1998).
4
 The City of Chicago, Findings Regarding Aircraft Emissions: O’Hare Airport and
Surrounding Communities (December 1999).
5
 Massachusetts Port Authority, Air Quality Initiative for Boston Logan International
Airport (March 2001).




Page 40                                        GAO-03-252 Aviation and the Environment
                       Appendix II: Types, Amounts, and Impact of
                       Emissions from Aviation-related Sources




                       estimated that the Dallas/Fort Worth International Airport was responsible
                       for 6 percent of nitrogen oxides in the metropolitan area.6

                       The amount of emissions attributable to each source varies by airport.
                       According to a 1997 study of four airports,7 ground access vehicles were
                       the most significant source of mobile emissions, responsible for 45 to 68
                       percent of the airports’ volatile organic compounds and 27 to 63 percent of
                       the nitrogen oxides emitted from mobile sources.8 Aircraft operations
                       were found responsible for the next largest share of emissions from
                       mobile sources, with total contributions of 15 to 38 percent and 26 to 37
                       percent for volatile organic compounds and nitrogen oxides, respectively.
                       Ground support equipment accounted for 12 to 13 percent of total
                       emissions from volatile organic compounds and 14 to 20 percent of total
                       nitrogen oxides from mobile sources at the airports. The report also found
                       that auxiliary power units for aircraft contributed a small amount of the
                       emissions from volatile organic compounds and 9 to 20 percent of total
                       nitrogen oxides emissions from mobile sources. According to the report,
                       data on particulate matter emissions is not available for aircraft and
                       auxiliary power units, but ground access vehicles contribute one type of
                       particulate matter at 1.3 to 2.7 the rate emitted by ground support
                       equipment.

                       Some pollutants associated with aviation activities can increase the risk of
Health and             a variety of health and environmental impacts. However, attributing these
Environmental Impact   impacts to any particular source is extremely difficult because of the
                       multiplicity of pollution sources in urban areas and the complexities
of Pollutants          involved in determining the exact causes of disease and environmental


                       6
                        Our estimates were developed from information contained in Dallas/Fort Worth
                       International Airport Emissions Inventory (July 1998) and emissions inventories for the
                       Dallas/Forth Worth metropolitan area contained in that area’s State Implementation Plan.
                       7
                        Energy and Environmental Analysis, Inc., Analysis of Techniques to Reduce Air
                       Emissions at Airports, (Arlington, VA: June 1997). The four airports included in this study,
                       which was conducted for EPA, were Baltimore-Washington International Airport, Boston
                       Logan International Airport, Los Angeles International Airport, and Phoenix Sky Harbor
                       International Airport.
                       8
                        According to EPA, mobile sources are moving objects that release pollution; mobile
                       sources include cars, trucks, buses, planes, trains, motorcycles, and gasoline-powered lawn
                       mowers. Mobile sources are divided into two groups: road vehicles, which include cars,
                       trucks and buses, and nonroad vehicles, which include trains, planes, and lawn mowers.
                       Mobile sources are distinguished from stationary sources, which are places or objects from
                       which pollutants are released and which do not move around. Stationary sources include
                       power plants, gas stations, incinerators, houses, etc.




                       Page 41                                         GAO-03-252 Aviation and the Environment
Appendix II: Types, Amounts, and Impact of
Emissions from Aviation-related Sources




damage. The limited amount of research available indicates that the
impact of the pollutants associated with airport activities is no more
pronounced in the areas near airports than it is in other urban areas.
Nevertheless, the cumulative impact of pollution from all sources can
affect health and the environment.

The pollutant of most concern in the United States and other industrial
countries is ozone, which is formed when nitrogen oxides, some types of
volatile organic compounds, and other chemicals are combined and
heated in the presence of light in the atmosphere. Ozone been shown to
aggravate respiratory aliments, such as bronchitis and asthma. Research
has indicated that certain levels of ozone affect not only people with
impaired respiratory systems, but healthy adults and children as well.
Exposure to ozone for several hours at relatively low concentrations has
been found to significantly reduce lung function and induce respiratory
inflammation in normal, healthy people during exercise.9

In addition, according to EPA, there is growing public concern over
emissions of air toxics, which include benzene, formaldehyde, and
particulate matter, because of their potential adverse effects on health.
Some of these emissions are associated with aviation activities. EPA’s
1996 National Toxics Inventory indicates that amounts of hazardous air
pollutants produced by aircraft are small relative to other sources such as
on-road vehicles. However, EPA’s national estimates are based on limited
data, and very little data is available on toxic and particulate matter
emissions in the vicinity of airports. A study of emissions at Los Angeles
International Airport is expected to shed some light on the subject. In
addition, FAA is involved in a study on identifying methods to measure
aircraft particulate matter emissions.

In the upper atmosphere, aircraft emissions of carbon dioxide and other
greenhouse gases can contribute to climate change. Greenhouse gases can
trap heat, potentially increasing the temperature of the earth’s surface and
leading to changes in climate that could result in such harmful effects as
coastal flooding and the melting of glaciers and ice sheets. According to a
1999 report by the Intergovernmental Panel on Climate Change, conducted
under the auspices of the United Nations, global aircraft emissions in


9
 Environmental Protection Agency, Environmental Fact Sheet: Adopted Aircraft
Emissions Standards (EPA 420-F-97-010, April 1997) and Federal Aviation Administration,
Air Quality Procedures For Civilian Airports and Air Force Bases (Washington: April
1997).




Page 42                                      GAO-03-252 Aviation and the Environment
Appendix II: Types, Amounts, and Impact of
Emissions from Aviation-related Sources




general accounted for approximately 3.5 percent of the warming generated
by human activities.10 Jet aircraft are also the largest source of emissions
generated by human activity that are deposited directly into the upper
atmosphere. Carbon dioxide is the primary aircraft emission; it survives in
the atmosphere for over 100 years and contributes to climate change. In
addition, other gases and particles emitted by jet aircraft including water
vapor, nitrogen oxides, soot, contrails, and sulfate combined with carbon
dioxide can have two to four times as great an effect on the atmosphere as
carbon dioxide alone, although some scientists believe that this effect
requires further study. The Intergovernmental Panel on Climate Change
concluded that aircraft emissions are likely to grow at 3 percent per year
and that the growing demand for air travel will continue to outpace
emission reductions achieved through technological improvements, such
as lower emitting jet engines.

Table 6 summarizes the possible environmental effects of the major
pollutants associated with aviation related activities on the human health
and the environment.




10
 Intergovernmental Panel on Climate Change, Aviation and the Global Atmosphere (1999).




Page 43                                      GAO-03-252 Aviation and the Environment
                                           Appendix II: Types, Amounts, and Impact of
                                           Emissions from Aviation-related Sources




Table 6: Health and Environmental Effects of Air Pollutants

 Pollutant                 Health effects                                         Environmental effects
 Ozone                     Lung function impairment, effects on exercise          Crop damage, damage to trees, and decreased
                           performance, increased airway responsiveness,          resistance to disease for both crops and
                           increased susceptibility to respiratory infection,     ecosystems.
                           increased hospital admissions and emergency room
                           visits, pulmonary inflammation, and lung structure
                           damage (long term).
 Carbon monoxide           Cardiovascular effects, especially in those persons  Adverse health effects on animals similar to
                           with heart conditions.                               effects on humans.
 Nitrogen oxides           Lung irritation and lower resistance to respiratory  Acid rain, visibility degradation, particle formation,
                           infections.                                          contribute toward ozone formation, and act as a
                                                                                greenhouse gas in the atmosphere and, therefore,
                                                                                may contribute to climate change.
 Particulate matter        Premature mortality, aggravation of respiratory and  Visibility degradation, damage to monuments and
                           cardiovascular disease, changes in lung function and buildings, safety concerns for aircraft from
                           increased respiratory symptoms, changes to lung      reduced visibility.
                           tissues and structure, and altered respiratory
                           defense mechanisms.
 Volatile organic          Eye and respiratory tract irritation, headaches,     Contribute to ozone formation, odors, and have
 compounds                 dizziness, visual disorders, and memory impairment. some damaging effect on buildings and plants.
 Carbon dioxide, water     None.                                                Act as greenhouse gases in the atmosphere and,
 vapor, and contrails                                                           therefore, may contribute to climate change.
 Sulfur dioxide            Respiratory irritant. Aggravates lung problems,      Causes damage to crops and natural vegetation.
                           particularly for individuals with asthma.            In presence of moisture and oxygen, sulfur dioxide
                                                                                converts to sulfuric acid, which can damage
                                                                                marble, iron, and steel.
Source: EPA and FAA.




                                           Page 44                                         GAO-03-252 Aviation and the Environment
               Appendix III: Federal, State, and
Appendix III: Federal, State, and
               International Responsibilities for Controlling
               Aviation-related Emissions


International Responsibilities for Controlling
Aviation-related Emissions
               The federal government and the states have responsibility for regulating
               sources of aviation emissions under the Clean Air Act, which was
               established to improve and protect air quality for human health and the
               environment.1 In addition, a United Nations entity, the International Civil
               Aviation Organization (ICAO), establishes international aircraft emissions
               standards, studies aviation emissions-related issues, and provides
               guidance for controlling these emissions. ICAO includes 188 member
               countries, which have agreed to adopt, to the extent possible, standards
               set by ICAO.

               For aircraft or aircraft engine emissions, the Clean Air Act gives EPA the
               authority2 to establish emission standards. EPA, in consultation with FAA,
               has chosen to adopt the international emissions standards established by
               ICAO. FAA serves as the United States’ representative to ICAO’s
               Committee on Aviation Environmental Protection, which is responsible for
               assessing aviation’s impact on the environment and establishing the
               scientific and technological basis for new gaseous emissions standards for
               aircraft engines. The committee has established several working groups to
               identify and evaluate emissions-reduction technology and operational
               measures and market-based options to reduce emissions. Both FAA and
               EPA participate in these working groups. In addition, FAA is responsible
               for monitoring and enforcing U.S. manufacturers’ compliance with aircraft
               emissions standards, which it does in part through its process for
               certifying new aircraft engines.

               In addition, the federal government plays a role in developing technologies
               to reduce aircraft emissions. NASA, in partnership with the aviation
               industry and universities, conducts research into improving the
               capabilities and efficiency of commercial aircraft. Part of this effort
               includes developing more fuel efficient and lower emitting engines. Over
               the years, NASA has been credited with contributing to technologies that
               have significantly lowered the amount of fuel consumed by jet engines;
               this in turn has reduced some emissions, particularly the greenhouse gas,
               carbon dioxide.


               1
                42 U.S.C 7401-7626. The amendment to the Clean Air Act in 1990 provided for a number of
               related programs designed to protect health and control air pollution. The 1990
               amendments established new programs and made major changes in the ways that air
               pollution is controlled. See U.S. General Accounting Office, Air Pollution: Status of
               Implementation and Issues of the Clean Air Act Amendments of 1990, GAO/RCED-00-72
               (Washington, D.C.: Apr.17, 2000).
               2
               See 42 U.S.C. 7571 of the Clean Air Act.




               Page 45                                          GAO-03-252 Aviation and the Environment
Appendix III: Federal, State, and
International Responsibilities for Controlling
Aviation-related Emissions




Under the Clean Air Act, EPA has jurisdiction for establishing national
standards for all other mobile sources of emissions, including those
associated with airport operations—such as ground support equipment
and ground access vehicles such as automobiles, trucks, and buses
operating on airport property. In establishing these emissions standards,
EPA is to take into consideration the time it takes to develop the
necessary technology and the cost of compliance.

The Clean Air Act also directs EPA to establish national standards for
ambient air quality, and these standards can affect airport operations and
expansion plans. EPA has set National Ambient Air Quality Standards for
carbon monoxide, lead, nitrogen dioxide, particulate matter, ozone, and
sulfur dioxide. EPA has labeled them criteria pollutants because the
permissible levels established for them are based on “criteria” or
information on the effects on public health or welfare that may be
expected from their presence. The criteria pollutants are directly or
indirectly generated by multiple sources, including airport activities. Local
areas not meeting the standards for criteria pollutants are referred to as
nonattainment areas. The act groups nonattainment areas into
classifications based on the extent to which the standards for each criteria
pollutant are exceeded and establishes specific pollution controls and
attainment dates for each classification. The act has set 2010 as the
deadline for extreme ozone nonattainment areas to meet the standards.
(California is currently the only state with such an area).

The Clean Air Act also authorizes EPA to set ambient air quality standards;
however, the states, which can adopt EPA’s or their own more stringent
standards, are responsible for establishing procedures to attain and
maintain the standards. Under the act, states that have areas in
nonattainment, must adopt plans—known as state implementation plans—
for attaining and maintaining air quality standards and submit the plans to
EPA for approval. State implementation plans are based on analyses of
emissions from all sources in the area and computer models to determine
whether air quality violations will occur. If data from these analyses
indicate that air quality standards would be exceeded, the states are
required to impose controls on existing emission sources to ensure that
emissions do not exceed the standards. States can require control
measures on airport emissions sources for which they are not preempted
from regulating, such as power plants and ground access vehicles, and, to




Page 46                                          GAO-03-252 Aviation and the Environment
Appendix III: Federal, State, and
International Responsibilities for Controlling
Aviation-related Emissions




a limited extent, ground support equipment.3 However, states cannot
control emissions from sources they are preempted from regulating
including aircraft, marine vessels, and locomotives. If a state fails to
submit or implement an adequate implementation plan, EPA can impose
an implementation plan.

FAA is responsible for ensuring that its actions supporting airport
development projects—such as providing funding for those projects—
comply with federal environmental requirements, including those
pertaining to air quality. The National Environmental Policy Act of 1969
sets forth a broad national policy intended to protect the quality of the
environment. The act requires that federal actions receive an
environmental review, which includes the impact on air quality, before
federal decisions are made and actions are taken. For example, federally-
funded proposals to construct airport runways require action by FAA. For
airport projects, FAA is the lead agency responsible for the environmental
reviews and for the approval of the airports’ proposed design. EPA
examines the environmental review documents prepared by FAA and
other federal agencies.

The “general conformity rule” of the Clean Air Act directs federal agencies,
such as FAA to ensure that federal actions at airports not delay the
attainment or maintenance of ambient air quality standards. Therefore,
FAA must determine, usually as part of the environmental review, that the
estimated amount of emissions caused by a proposed federal action at an
airport comply with the state implementation plan for meeting the
standards. FAA cannot approve an action unless it complies with the plan.
In order to demonstrate compliance, the airport could be required to
implement emission control measures, such as converting airport vehicles
to alternative lower emitting fuels.

To help carry out its responsibilities under the Clean Air Act and the
National Environmental Policy Act, FAA developed the Emissions and
Dispersion Modeling System, which is a computer model that estimates
the amount and type of emissions from airport activities. FAA, airports,



3
 California is authorized, under section 209(e)(2)(B) of the Clean Air Act to enact and
enforce nonroad engine standards, which apply to ground support equipment. States with
nonattainment areas can promulgate standards identical to those of California. Otherwise,
the federal standard applies. In November 2002, EPA adopted emissions standards for
nonroad large spark emissions engines such as those used in much of the ground support
equipment currently in service at airports.




Page 47                                          GAO-03-252 Aviation and the Environment
Appendix III: Federal, State, and
International Responsibilities for Controlling
Aviation-related Emissions




and others use the model to assess the local air quality impacts of airport
development projects. Typically, the model is used to estimate the amount
of emissions produced by aircraft, ground support equipment, and other
sources operating at the airport or in the nearby vicinity. The model also
reflects the way these airport emissions are dispersed in the atmosphere
due to wind and other factors. The dispersion analysis is intended to
assess the concentrations of the emissions at or near the airport and,
thereby, help to indicate the effect of the emissions on local air quality.

FAA is also engaged in several research projects to improve the
understanding of aircraft emissions and methods for quantifying them. For
example, FAA is working with the Society of Automotive Engineers to
develop a protocol for measuring particulate matter emissions from
aircraft. FAA is also studying ways to increase the accuracy of aircraft
emission dispersion models and is analyzing the air quality impact of
aircraft operations at or above 3000 feet.




Page 48                                          GAO-03-252 Aviation and the Environment
               Appendix IV: Efforts by Three States to
Appendix IV: Efforts by Three States to
               Reduce Aviation-related Emissions



Reduce Aviation-related Emissions

               Three states with major commercial airports in nonattainment areas—
               California, Texas, and Massachusetts—have targeted airports for
               emissions reductions.


               California has more major commercial airports—seven—than any other
California     state, and all of them are located in nonattainment areas for ozone.
               Although none of the airports are a major source of ozone precursors such
               as nitrogen oxides and volatile organic compounds, California air quality
               authorities have turned their attention to airports as a source of reductions
               needed to reach and maintain attainment of ozone standards because they
               believe they have exhausted other sources, including large sources such as
               power plants and small sources like lawn mowers. The Los Angeles region
               is the only one in the country classified as an extreme nonattainment area
               for ozone. According to state environmental officials, emissions from all
               airport activities1 contributed about 1 to 2 percent of the pollution in the
               Los Angeles region in 2000, and this is projected to increase to nearly 4
               percent by 2020. State environmental officials attribute this projected
               increase in the airports’ ozone contribution to an expected doubling of
               aircraft emissions coupled with a 50 percent decrease in emissions from
               other sources. These projections do not take into account the reductions
               in aircraft activity as a result of the events of September 11, 2001, and the
               financial uncertainties of the airline industry.

               Because of the severity of the nonattainment level in the Los Angeles area,
               the state requires reductions from all sources, including airports, by 2010.
               Along with Los Angeles’ local air quality agency, the California Air
               Resources Board has negotiated with EPA and airlines for a memorandum
               of understanding for voluntary emission reductions from ground support
               equipment.2 According to California Air Resources Board officials,
               emission reductions would be achieved by replacing older, high polluting
               ground support equipment with new cleaner gas and diesel fueled
               equipment or equipment operating with alternative energy sources, such
               as electricity. In doing so, the officials expect an 80 percent reduction of
               emissions from ground support equipment that are used at five airports—



               1
                The airports in the Los Angeles region include Burbank, Long Beach, Los Angeles
               International, John Wayne (Orange County), Ontario International, and Palm Springs
               International.
               2
                The California Air Resources Board has reached agreement with the major carriers in
               Southern California to reduce emissions from ground support equipment.




               Page 49                                       GAO-03-252 Aviation and the Environment
        Appendix IV: Efforts by Three States to
        Reduce Aviation-related Emissions




        Los Angeles International, Burbank, Ontario International, Long Beach,
        and John Wayne—in the Los Angeles region by 2010.

        California’s efforts to cut emissions from ground support equipment in the
        Los Angeles area are part of an aggressive statewide campaign to reduce
        airport pollution. In addition to using its limited authority under the Clean
        Air Act to implement airport related emissions reductions, the state has
        also established criteria for issuing air quality certifications provided for in
        federal law.3 Under this law, before federal funds are allocated for projects
        involving a new airport, a new runway, or a major runway extension, the
        state governor must certify that there is reasonable assurance that the
        project will be “located, designed, constructed, and operated in
        compliance with applicable air and water quality standards.” The state has
        developed a unique set of criteria for determining whether a proposed
        airport expansion project would have an impact on the environment. If the
        project exceeds one of the criteria, the airport is required to implement
        emissions mitigation measures in order to attain certification. For
        example, the certification for a runway project was invoked when the
        Sacramento International Airport planned to increase the number of
        parking spaces. The criteria on which the certification was based included
        annual increases of more than 7 million passengers or 139,000 aircraft
        operations (i.e., landings and takeoffs) or a permanent increase of more
        than 4,200 parking spaces. The airport’s plans exceeded the number of
        parking spaces and, as a result, were required to implement emission
        mitigation measures in order to build the parking spaces. According to
        state officials, California is the only state to develop such criteria for
        certifying airport expansion projects. As of December 2002, three airports
        in California—Sacramento International, San Jose International, and
        Ontario International—have initiated expansion projects that required
        state certification.


        Texas has four regions in nonattainment of national air quality standards
Texas   for ozone, but the Houston and Dallas/Fort Worth regions have required
        the most extensive emission control measures for reaching attainment.
        These two regions contain the state’s four largest airports—Dallas/Fort
        Worth International, Dallas Love Field, George Bush International/
        Houston, and Houston Hobby—all of which are among the nation’s 50
        busiest airports. The Houston area has one of the worst ozone problems in


        3
        49 U.S.C. 47106.




        Page 50                                   GAO-03-252 Aviation and the Environment
Appendix IV: Efforts by Three States to
Reduce Aviation-related Emissions




the country and has been designated as a severe nonattainment area,
requiring substantial control measures in order to comply with the Clean
Air Act. Dallas-Fort Worth, on the other hand, has a much less serious
ozone problem but has been penalized by EPA for not meeting its
attainment schedule. EPA classified the Dallas/Fort Worth region as a
moderate ozone nonattainment area in the early 1990s, which meant that
the region was required to demonstrate attainment of the 1-hour ozone
standard4 by November 1996. However, air quality data from the region
showed that the area failed to meet the attainment goal in 1996, which
resulted in EPA reclassifying the severity level of the region from
moderate to serious. The downgrading of the Dallas region’s classification
forced state and local authorities to develop a new state implementation
plan with more extensive control measures. The state’s environmental
agency, the Texas Natural Resource Conservation Commission5, included
emissions from airport activities among the top ten highest sources of
nitrogen oxides emissions from nonroad mobile sources in both the
Dallas-Fort Worth and Houston regional areas.

Noting that the emissions inventories for both Houston and Dallas-Fort
Worth placed airports in the top 10 sources for nitrogen oxides emissions
of nonroad mobile sources, which contribute to ozone formation, the
Texas Natural Resource Conservation Commission determined that
control measures for each area were warranted. For Dallas-Fort Worth,
the commission revised the state implementation plan for the area to
include reduction of nitrogen oxides emissions from ground support
equipment at both major commercial airports in the area—Dallas/Forth
Worth International and Dallas Love Field. The plan called for a 90 percent
reduction of nitrogen oxides emissions from ground support equipment by
2005. The airline industry challenged the state rule by filing a lawsuit,
citing the Clean Air Act’s preemption rule, which it argued prohibited
states and local authorities from regulating ground support equipment.
The lawsuit was dropped in October 2000 when the commission, the cities
of Dallas and Fort Worth (which operates the major airports), and the
affected airlines—American, Delta, and Southwest—reached a voluntary
agreement to achieve a 90 percent reduction in nitrogen oxides emissions
attributable to ground support equipment or other equipment by 2005. The


4
 The 1-hour ozone standard is the average amount of ozone allowed by EPA in the lower
atmosphere during a one-hour period.
5
The agency’s name was recently changed to the Texas Commission on Environmental
Quality.




Page 51                                      GAO-03-252 Aviation and the Environment
                Appendix IV: Efforts by Three States to
                Reduce Aviation-related Emissions




                commission brokered a similar agreement with the city of Houston as its
                operator of the airports and the affected airlines. Under both the
                Dallas/Fort Worth and Houston agreements, the affected carriers
                voluntarily agreed to reductions equivalent to 75 percent of nitrogen
                oxides emitted from ground service equipment and the cities—Dallas-
                Forth Worth, and Houston—as the operators of the airports agreed to be
                responsible for the remaining 15 percent to achieve the 90 percent
                reduction.


                The Boston area is classified as a serious ozone nonattainment area and
Massachusetts   state environmental officials are under increasing pressure by citizens,
                community groups, and industry to control emissions from Boston’s Logan
                International Airport. State environmental officials have estimated that
                while only a small amount of total nitrogen oxides emissions in the area
                are attributable to aircraft, these emissions will continue to increase. They
                estimate that other emission sources at the airport, such as ground
                support equipment, will eventually begin to decrease as they are replaced
                by lower polluting equipment. The Boston airport is also consistently
                ranked as the airport with the second highest number of air travel delays
                in the nation. These air travel delays add to regional air quality problems
                because idling aircraft contribute to pollution. To meet a growing travel
                demand, Boston airport officials have proposed building a new runway to
                allow the airport to improve operating efficiency, thereby reducing
                emissions from idling aircraft. As part of this proposal, the airport also
                agreed that emissions would not exceed 1999 levels.

                To address airport operation delays and reduce emissions, airport officials
                have considered three strategies—peak period pricing, emissions credit
                trading, and reducing emissions from ground support equipment.6 Peak
                period pricing is a demand management strategy that raises landing fees
                during designated air traffic peak hours, which is expected to induce some
                air carriers to discontinue or reduce operations during peak periods. With
                fewer aircraft waiting to taxi and land during peak periods, emissions from
                aircraft would be reduced and regional air quality would be improved. An
                emissions credit trading program is designed to allow facilities to meet
                emission reduction goals by trading and transferring air emission credits
                with emission sources that surpassed their allotted targets. Used by EPA



                6
                 Air carrier representatives have noted that the airport’s proposed strategies could be
                subject to legal challenge if they are implemented.




                Page 52                                         GAO-03-252 Aviation and the Environment
Appendix IV: Efforts by Three States to
Reduce Aviation-related Emissions




to reduce pollutants that contribute to acid rain, the emission credit
trading program allows sources, such as industry, the flexibility to meet
their reduction obligations in a more cost effective manner. Because
emission credits are considered “additional” or “surplus” to those that are
regulated and otherwise reduced under federal and state laws, they aid in
achieving an overall decline in emissions regionwide, according to Boston
airport officials. Similar to situations at the major airports in both
California and Texas, state and airport officials have also focused on
reducing emissions from ground support equipment.

In the wake of the events of September 11, 2001, which resulted in a
reduction of flights and emissions at the Boston airport, the airport’s
operator—Massachusetts Port Authority—believes that peak pricing and
emissions trading will not be needed to keep emissions below 1999 levels
for several years. The Port Authority, however, continues to work with
airport tenants to implement voluntary emission reduction strategies. In
addition, in an August 2002 Record of Decision approving plans for a new
runway and taxiways, FAA directed the Port Authority to develop and
submit a plan for peak period pricing or other demand management
strategies to reduce delays, which the Port Authority had committed to
complete this plan as part of the state environmental review process,
before initiating construction. In the Record of Decision, FAA pointed out
that the program would have to comply with applicable federal
constitutional and other requirements.




Page 53                                   GAO-03-252 Aviation and the Environment
                 Appendix V: Airports’ and Airlines’ Efforts To
Appendix V: Airports’ and Airlines’ Efforts To
                 Reduce Emissions



Reduce Emissions

                 Many of the nation’s busiest airports, in conjunction with air carriers, have
                 voluntarily implemented control measures to reduce emissions by
                 activities that include modifying the operating procedures of aircraft,
                 using alternative fuels to run ground support equipment, and reducing the
                 number of passenger vehicles entering and exiting the airport.


                 Although airports have no control over emissions from aircraft, they can
Aircraft         encourage air carriers to reduce emissions as much as possible through
                 modified operating procedures. For example, limiting the number of
                 running engines during taxiing of aircraft can reduce the emission of
                 nitrogen oxides and volatile organic compounds. According to airport
                 officials at the Boston Logan International Airport, some pilots use single-
                 engine taxiing with some aircraft to reduce emissions. Another example is
                 reducing the use of engine reverse thrust to slow an aircraft to taxi speed
                 after it lands. This procedure reduces nitrogen oxides emissions, but it
                 may occur at the expense of slightly higher emissions of volatile organic
                 compounds if the taxi time is increased because a runway turnoff is
                 missed. Many factors are involved in the decision to use reverse thrust,
                 including runway length and width, runway surface and taxiway
                 conditions, weather conditions, and aircraft type.

                 Modifying the operating procedures of aircraft does not require additional
                 equipment or aircraft modifications, but it is done at the discretion of the
                 pilot. Under federal regulations, the commanding pilot of the aircraft is
                 responsible for the safety of the passengers, crewmembers, cargo, and the
                 airplane, and any procedure that modifies aircraft operation is at the
                 discretion of the pilot. In addition, modifications to operating procedures
                 may not be feasible in all weather conditions, with all aircraft, and/or at all
                 airports.


                 Most ground support equipment used by air carriers at airports is fueled
Ground Support   by gasoline or diesel. Replacing that equipment with cleaner-burning gas
Equipment        or diesel engines or equipment powered by alternative fuels—such as
                 electricity, liquefied petroleum gas, and compressed natural gas—could
                 result in reduced emissions. A reliable and comprehensive database of the
                 ground support equipment in use does not exist; however, according to
                 FAA, there are about 72,000 pieces of such equipment in operation. The
                 Air Transport Association estimated that of the pieces of ground support
                 equipment in used in 1999, about 30 to 40 percent operate on diesel fuel;
                 50 to 60 percent operate on gasoline; and about 10 percent use alternative
                 fuels. Several airports we visited, including Los Angeles International,


                 Page 54                                          GAO-03-252 Aviation and the Environment
Appendix V: Airports’ and Airlines’ Efforts To
Reduce Emissions




Sacramento International, Dallas/Fort Worth International, Boston Logan
International, and Atlanta Hartsfield, provided air carriers with the
infrastructure necessary to operate alternatively fueled ground support
equipment, and some carrier have begun converting their fleets of ground
support equipment to alternative fuels. Los Angeles International, for
instance, provided a varied alternative fuel infrastructure, including both
compressed and liquefied natural gas refueling stations and electric
charging stations, which offered air carriers different options to use
alternative fueled equipment. Airport officials told us that air carriers have
been using the alternative fuel stations to refuel their ground support
equipment.

FAA reported1 that replacing conventionally-fueled ground support
equipment with alternatively-fueled equipment is the most cost effective
way to reduce emissions at airports. Additionally, equipment originally
designed to use the alternative fuels has less impact on the environment
than equipment that is converted from using a conventional fuel to an
alternative fuel; however, it is also more costly up front, and alternative
fuel technology does not currently exist for some types of ground support
equipment. Airports and air carriers use about 24 different types of ground
support equipment, such as cargo loaders, aircraft pushback tractors,
baggage tugs, and service trucks; and according to aviation industry
officials, conversion of equipment from conventional to alternative fuel
has had a mixed result in terms of operating the equipment. According to
airline officials, liquefied petroleum and compressed natural gas vehicles
require larger fuel tanks and are harder to operate; the cost for the
alternative fuel infrastructure engines for ground support equipment is
also very expensive. Air carriers and airports commonly have had to use a
mixed fleet of liquefied petroleum and compressed natural gas and electric
ground support equipment because of limitations of the various types of
alternative fuel sources. For example, electricity has not been sufficiently
powerful to run some of the ground service equipment that bear
significant loads. In addition, some types of electric equipment do not
work well in cold weather conditions. According to the Air Transport
Association, for these and other reasons, no one equipment size or type
fits all airlines’ needs.




1
 Federal Aviation Administration, Air Quality Procedures For Civilian Airports and Air
Force Bases (Washington, D.C.: April 1997).




Page 55                                          GAO-03-252 Aviation and the Environment
                         Appendix V: Airports’ and Airlines’ Efforts To
                         Reduce Emissions




                         A trend at airports is to provide electricity and air conditioning service for
Providing Electric       aircraft at the gates, which can permit a reduction in the use of aircraft
Power at Gates           auxiliary power units and thereby reduce emissions, according to FAA.
                         Airports are not required to install boarding gates that provide electricity
                         to parked aircraft, but an FAA report notes that some airports have been
                         proactive in reducing emissions and have invested in these electric gates.2
                         The report explains that electric gates operate at greater energy efficiency
                         than auxiliary power units, which support aircraft with power and
                         ventilation systems when they are parked at the gates, and can
                         substantially reduce emissions. Many airports, including Los Angeles
                         International, Sacramento International, Dallas/Fort Worth International,
                         and Boston Logan International provide electric power for parked aircraft,
                         which allows aircraft to turn off their auxiliary power units while
                         maintenance and cleaning crews prepare the aircraft for the next flight.
                         However, air carriers are not required to use the electric gates, and some
                         chose not to use them because they hinder the efficiency of their
                         operations. For instance, one airline that specializes in getting its aircraft
                         into and out of airports quickly—in 20 minutes or less—rarely uses the
                         electricity provided by the airport, instead running the auxiliary power
                         unit the entire time aircraft are at the gate, according to officials of that
                         airline. These officials note that electric gates are only useful for those
                         aircraft that are parked for 30 to 45 minutes or longer before they take off
                         because of the time it takes to hook the aircraft up to the system.


                         Although EPA already regulates emissions from most passenger vehicles
Passenger Vehicles       and trucks, options are available to further reduce emissions from theses
                         sources at airports. Vehicles making trips to and from airports include
                         employee and private passenger vehicles, airport and tenant-owned fleet
                         vehicles, public transport vehicles and shuttles, and cargo vehicles for
                         deliveries. All the airports we visited have implemented or are in the
                         process of implementing emission reduction efforts for this emissions
                         source. Some emission reduction measures that airports have applied to
                         such ground access vehicles include the following:

                     •   Dallas/Fort Worth International airport has consolidated its rental car
                         facilities and, according to airport officials, the consolidation effort has
                         reduced rental car related emissions by 95 percent. In addition, the single



                         2
                          Federal Aviation Administration, Air Quality Procedures For Civilian Airports and Air
                         Force Bases (Washington: April 1997).




                         Page 56                                          GAO-03-252 Aviation and the Environment
                     Appendix V: Airports’ and Airlines’ Efforts To
                     Reduce Emissions




                     shuttle service that resulted from consolidating the rental car facilities
                     uses alternative fuel shuttles. George Bush Intercontinental/Houston plans
                     to consolidate its rental car facilities; and Los Angeles International,
                     Atlanta Hartsfield, and Boston Logan International are also considering
                     the option.
                 •   Dallas/Fort Worth International, Los Angeles International, and
                     Sacramento International all have promoted some kind of
                     employee/tenant commuter rideshare program. According to Los Angeles
                     International Airport officials, about 25 percent of airport employees
                     participate in a commuter rideshare program.
                 •   Los Angeles International restructured its airport shuttle-van program in
                     1999 by reducing the number of shuttle vans authorized to make passenger
                     pickups at the airport and requiring them to phase-in alternative fuel
                     vehicles into their fleets. The airport expects all of the authorized
                     operators to use alternative fuel vehicles by 2003. The airport is also
                     considering requiring taxicabs serving the airport to operate on natural
                     gas.
                 •   Both Chicago O’Hare International and Dallas/Fort Worth International
                     airports have built an electric automated transport system, also known as
                     a “people mover,” within the airport property to transport passengers
                     between terminals. Chicago O’Hare International airport also offers direct
                     rail service to the city center and provides alternative transportation to
                     passengers and airport employees entering/exiting the airport. Los Angeles
                     International provides alternative public transportation with a bus service
                     that travels between the airport and the park-and-ride station at the Van
                     Nuys Airport.



                     Airports have also reduced emissions from other sources, such as their on-
Other Measures       site utilities plants. Los Angeles International airport’s central utilities
                     plant operates under a cogeneration energy saving system, which
                     simultaneously generates electrical power and steam. Some electrical
                     power is sold to the local electric company, and the steam provides
                     heating and air conditioning (by powering steam refrigeration chillers) for
                     the airport’s buildings and central terminal area. According to airport
                     officials, Los Angeles International receives more than $3 million in
                     emissions credit each year for the emission controls achieved with its
                     central utilities plant. Dallas/Fort Worth International airport also
                     generates electricity with its solar power generators, which produce lower
                     emissions than traditional powered generators. Airport officials stated that
                     they have the capacity to build cogeneration plants using solar power and
                     sell the power/surplus electricity to the state as well. The airport is trying
                     to negotiate with federal agencies to receive credits for the amount of


                     Page 57                                          GAO-03-252 Aviation and the Environment
Appendix V: Airports’ and Airlines’ Efforts To
Reduce Emissions




emission reductions achieved by using solar power energy and selling
surplus electricity to the state. If successful, the airport could use these
credits to gain approval of future expansion projects that increase
emissions.




Page 58                                          GAO-03-252 Aviation and the Environment
               Appendix VI: Overview of Aircraft Fuel,
Appendix VI: Overview of Aircraft Fuel,
               Noise, and Nitrogen Oxides Reduction
               Technologies


Noise, and Nitrogen Oxides Reduction
Technologies
               Fuel efficiency improvements involve every aspect of an aircraft’s design.
               Traditionally, about 40 percent of the improvements have come from
               airframe improvements and 60 percent from propulsive and engine
               improvements. Airframe improvements include improving the
               aerodynamic shape and structural efficiency (for example, reduced
               aircraft weight). Propulsive improvements have primarily resulted from
               increasing the size of the bypass fan and improving the shape of the
               bypass fan blades. Engine improvements have centered on increasing the
               pressure of the air that goes through the engine core (the engine operating
               pressure). The increased engine operating pressures allow more work to
               be extracted from a unit of fuel, thereby improving fuel consumption.

               One of the first major technology breakthroughs with commercial jet
               engines occurred in the mid-1960s with the introduction of the turbofan jet
               engine (see figure 3). This design uses a bypass fan in front of the jet
               engine core to move much of the propulsive air and bypass the core of the
               jet that contains the compressor, combustor, and turbine. The primary
               motivation for this advancement was increased fuel efficiency. However,
               the reduced noise of this new design was an additional benefit. Noise was
               reduced because the bypass air moves at a slower speed than the air going
               through the core. Further noise reductions have evolved over time by
               increasing the size of the bypass fans and improving the shapes of the
               bypass fan blades. Researchers at NASA have indicated they are facing
               diminishing returns as they seek to reduce noise by further improving
               bypass fans and aircraft surfaces. They are also exploring more advanced
               technologies such as using electronics to actively control noise.




               Page 59                                   GAO-03-252 Aviation and the Environment
                                       Appendix VI: Overview of Aircraft Fuel,
                                       Noise, and Nitrogen Oxides Reduction
                                       Technologies




Figure 3: Major Components of a Turbofan Engine (Two-Shaft High Bypass Engine)




                                       NASA, in association with jet engine manufacturers and the academic
                                       community, is working on several technologies to reduce nitrogen oxides
                                       emissions. NASA’s research to reduce nitrogen oxide emissions is a
                                       component of its Ultra Efficient Engine Technology Program. The goal of
                                       this program is to develop technologies that will enable U.S.
                                       manufacturers to compete in the global marketplace for new commercial
                                       gas turbine engines. An important aspect of this program is reducing jet
                                       engine emissions of nitrogen oxides. NASA has set what it considers




                                       Page 60                                   GAO-03-252 Aviation and the Environment
    Appendix VI: Overview of Aircraft Fuel,
    Noise, and Nitrogen Oxides Reduction
    Technologies




    ambitious goals1 for its nitrogen oxides reduction research. These goals
    include the following:

•   Demonstrate combustion technology, in a NASA test laboratory, that will
    reduce nitrogen oxides 70 percent relative to today’s standard. This
    equates to a 20-50 percent reduction compared with the best engines being
    produced today.
•   Demonstrate these technologies in engine combustor components by 2005.
•   Hand off the technologies to manufacturers in a timely fashion so they can
    be incorporated in new engines in the 2007-2010 time frame.
•   Study long-term concepts that could greatly reduce or eliminate nitrogen
    oxides emissions in the 2025-2050 time frame.

    According to representatives from jet engine manufacturers, nitrogen
    oxides reduction research is complex and time consuming and requires
    specialized and expensive test equipment. They also said that basic
    research needed to understand the formation of nitrogen oxides in jet
    engines and to make significant changes to current engine designs is so
    expensive and lacking in marketplace investment rewards that no
    significant or sustained basic research in this area would take place
    without NASA taking the lead.

    Adding to the complexities of this research is the extreme variation in jet
    engine designs. Other research and development by NASA and engine
    manufacturer is constantly raising engine-operating pressures as a way of
    improving fuel consumption and reducing greenhouse gas emissions.
    However, these developments tend to increase nitrogen oxides emissions,
    and further modifying engine designs to reduce nitrogen oxides has a
    direct impact on every other aspect of engine design: safety, operability,
    service life, operating costs, maintenance costs, and production costs. Jet
    engine manufacturers are taking divergent design approaches as they
    research how to maintain these other high-priority design characteristics
    while reducing nitrogen oxides emissions. As a result, NASA divides its
    resources over numerous projects.




    1
     NASA officials told us that their nitrogen oxides research goals are more ambitious than
    what they expect to actually achieve when their research is incorporated into production
    ready engine designs. This is because designs that work well during component level
    research testing will undergo modification as the complete engine design is refined to meet
    safety and operability requirements and fuel-efficiency goals.




    Page 61                                        GAO-03-252 Aviation and the Environment
Appendix VI: Overview of Aircraft Fuel,
Noise, and Nitrogen Oxides Reduction
Technologies




NASA’s Ultra Efficient Engine Technology Program is scheduled to
complete research and technology on aircraft engine combustor
refinements that reduce the formation of nitrogen oxides so that the
refinements can be introduced on aircraft by 2010. Because of the 30-year
projected life of commercial aircraft, it could take decades before enough
lower emitting aircraft are introduced in the commercial fleet to
contribute to significant reductions in nitrogen oxides. NASA’s nitrogen
oxides research under the Ultra Efficient Engine Technology Program is
centered on developing lean-burning rather than rich burning combustors
that are in commercial service today. These lean-burning combustors will
increase fuel/air mixing rates that, when combined with the lean fuel/air
ratios, will reduce temperatures locally in the combustor and thus reduce
the nitrogen oxides emissions generated. Because of funding constraints,
NASA does not plan to implement the next phase of development, which is
to examine the combustor improvements in a full engine test environment.
NASA is relying on the engine manufacturers to implement this full engine
development. Both NASA and aviation industry engineers said that this full
engine development phase will be far more complex and involve many
more design trade-offs than the combustor development phase.
Additionally, they acknowledged that some of the nitrogen oxides
reductions achieved during the combustor development phase would be
lost during the full engine development phase. NASA researchers indicated
these losses could be particularly severe because engine manufacturers
are concurrently making other design changes to their engines to minimize
fuel consumption and these changes will increase nitrogen oxides
emissions. Consequently, NASA researchers are not sure how many of the
improvements they expect to achieve by 2005 will survive as the engine
manufacturers take over responsibility for completing the development of
these improvements in a full engine test environment and then integrate
these improvements into production-ready engines.

NASA is also working on a long-term revolutionary jet engine design that
could significantly reduce all emissions including nitrogen oxides while
also reducing fuel consumption. Under its “intelligent propulsions
controls” design concept, engine functions are more precisely controlled
using computers. For example, with this design, the number of ports
delivering fuel to the engine combustion chamber would be greatly
increased, and each port would be computer controlled. NASA officials
are optimistic about the potential of this concept, but they added that
research is in the early stages and that it will probably take 20 years or
more to develop. NASA’s overall long-term research plan calls for
spending about $20 million per year over the next 5-year period to explore
improved fuel burn and nitrogen oxides emission reduction technologies.


Page 62                                   GAO-03-252 Aviation and the Environment
Appendix VI: Overview of Aircraft Fuel,
Noise, and Nitrogen Oxides Reduction
Technologies




NASA researchers are also studying the possibility of developing zero
emissions (except water) hydrogen-fueled aircraft with an electric
propulsion system. While they note that there would have to be many
breakthroughs in hydrogen storage and fuel cell technologies and high-
powered lightweight electric motors before a hydrogen-fueled commercial
airliner is feasible, they believe many of the needed breakthroughs could
occur in the next 50 years.

NASA2 is also researching nonengine methods that will indirectly reduce
nitrogen oxides (and all other emissions) by reducing fuel consumption.
This work includes more efficient airframes through aerodynamic
improvements, structural improvements (i.e., reducing aircraft weight),
and operational efficiencies (i.e., more fuel efficient flight routes, reduced
taxi time). Historically, 40 percent of aviation fuel improvements have
come from such efficiency improvements. Aviation emission experts
emphasize that it is important that research into these types of
improvements continue along with the engine research. The advantage of
these improvements is that all emissions are reduced simultaneously
without having to make emission trade-offs.




2
FAA, the aviation industry, and universities also participate with this research.




Page 63                                         GAO-03-252 Aviation and the Environment
              Appendix VII: Additional Information on Our
Appendix VII: Additional Information on Our
              Analysis of Aircraft Emissions



Analysis of Aircraft Emissions

              Using the Emissions and Dispersion Modeling System (version 4.01)
              computer model developed by FAA and fleet data obtained from AvSoft,
              we calculated the landing/takeoff emissions for every aircraft model and
              engine combination in the U.S. commercial aircraft fleet during 2001.
              (See appendix I for additional information on our methodology.) Tables 7
              and 8 provide additional information on our comparison of older and
              newest model Boeing 737s. As shown below, older model Boeing 737s,
              produced in 1969-1998, averaged 12.1 pounds of nitrogen oxides per
              landing/takeoff (see table 7), while the newest model Boeing 737s,
              produced in 1997-2201, averaged 17.9 pounds of nitrogen oxides per
              landing/takeoff (see table 8). Tables 9, 10, and 11 provide additional
              information about the calculations and commercial fleet for data
              presented earlier in this report.




              Page 64                                       GAO-03-252 Aviation and the Environment
                                             Appendix VII: Additional Information on Our
                                             Analysis of Aircraft Emissions




Table 7: Emission Information for Older Boeing 737s during Landing/Takeoff

                                                                          Number
                                   Pounds Pounds Pounds                    in U.S.       Number                               Average Pounds
                                   NOx per    CO     VOC                   fleet in      of LTOs      Oldest     Newest       number takeoff
                                         a       a       a
 Model           Engine              LTO per LTO per LTO                      2001        in 2001     in fleet   in fleet     of seats weight
 737-200         JT8D-15            13.361  9.912   1.296                       55       101,887        1977       1985          113.1 105000
 737-200         JT8D-15A           11.835 10.475   1.479                       65         85,577       1980       1988          113.7 105000
 737-200         JT8D-17            14.804  9.574   1.165                       21         31,620       1976       1987          106.6 105000
 737-200         JT8D-17(Q)         14.804  9.574   1.165                         1           879       1976       1976          128.0 105000
 737-200         JT8D-17A           12.801 10.421   4.204                         5         8,632       1983       1985          117.0 105000
 737-200         JT8D-7B            11.207 10.424   2.326                         1           181       1969       1969           56.0 100000
 737-200         JT8D-9A            12.079 10.591   2.042                       55       128,673        1968       1988          114.5 100000
 737-200C        JT8D-15            13.361  9.912   1.296                         1         2,139       1974       1974          111.0 105000
 737-200C        JT8D-17            14.804  9.574   1.165                         7        17,428       1979       1984          111.1 105000
 737-200C        JT8D-17A           12.801 10.421   4.204                         5        12,750       1983       1985          111.6 105000
 737-200C        JT8D-9A            12.075 10.590   2.042                         1         3,373       1980       1980          112.0 100000
 737-300         CFM56-3B-1         10.720 19.197   1.201                      380       842,336        1984       1997          130.8 122000
 737-300         CFM56-3B-2         12.496 17.811   0.991                      137       244,395        1984       1992          126.3 122000
 737-300         CFM56-3C-1         14.195 16.766   0.859                         9        12,355       1993       1998          126.9 122000
 737-400         CFM56-3B-2         12.496 17.811   0.991                       56         97,791       1988       1992          144.9 122000
 737-400         CFM56-3C-1         14.350 16.771   0.861                       41         71,175       1989       1999          138.9 133000
 737-500         CFM56-3B-1         11.617 19.278   1.204                       26         77,823       1990       1998          121.3 122000
 737-500         CFM56-3B-2         13.578 17.894   0.994                         3         5,188       1990       1990          104.0 122000
 737-500         CFM56-3C-1         15.451 16.852   0.862                      119       197,140        1990       1998          106.5 122000
                     b
 Weighted averages                  12.123 16.798   1.221
 Total                                                                         988     1,941,342
 Percentage of total U.S. commercial fleet                                   12.7%        17.6%
                                             Legend
                                             CO=carbon monoxide
                                             LTO= landing/takeoff
                                             NOx=nitrogen oxides
                                             VOC= volatile organic compounds
Source: GAO.

                                             Notes: Landing and takeoff data for U.S. aircraft in 2001 obtained from AvSoft. Emissions were
                                             calculated using FAA’s Emissions and Dispersion Modeling System, version 4.01. The following
                                             variables were assumed to be the same for all aircraft: (1) taxi-time: 15 minutes, (2) auxiliary power
                                             unit time: 26 minutes, and (3) ceiling height for emissions mixing with local air: 3,000 feet. The
                                             model’s default was used for takeoff weight.
                                             a
                                              Pounds of emissions per one landing/takeoff (LTO), which includes emissions for takeoff, climb to
                                             3,000 feet, approach, taxi, and auxiliary power unit.
                                             b
                                              The average was computed by weighting the emissions for a specific model/engine combination by
                                             the number of landings/takeoffs for that combination in 2001.




                                             Page 65                                                GAO-03-252 Aviation and the Environment
                                             Appendix VII: Additional Information on Our
                                             Analysis of Aircraft Emissions




Table 8: Emission Information for Newest Boeing 737s during Landing/Takeoff

                                                                   Number
                             Pounds      Pounds       Pounds        in U.S.     Number                               Average               Pounds
                                a
                            NOx per       CO per      VOC per       fleet in    of LTOS        Oldest       Newest number of                takeoff
 Model     Engine               LTO         LTO          LTO           2001      in 2001       in fleet     in fleet   seats                weight
 737-700 CFM56-7B-20          12.702      12.178        1.370              8       3,176         1998         2001     123.9                122000
 737-700 CFM56-7B-22          15.078      11.269        1.183           118     218,184          1997         2002     136.9                122000
 737-700 CFM56-7B-24          16.971      11.229        1.185            55       72,337         1998         2001     123.1                122000
 737-700 CFM56-7B-26          20.280       9.926        1.001              5       2,435         2001         2001     124.0                122000
 737-800 CFM56-7B-26          20.280       9.926        1.001           193     208,950          1998         2002     151.5                122000
 737-800 CFM56-7B-27          22.181       9.663        0.934            54       33,181         2000         2002     157.0                122000
 737-900 CFM56-7B-26          20.030      11.221        1.065            16        8,285         2001         2002     161.7                122000
 Weighted averagesb           17.883      10.651        1.097
 Total                                                                  449      546,548
 Percentage of total U.S. commercial fleet                           5.75%        4.96%
                                             Legend
                                             CO=carbon monoxide
                                             LTO=landing/takeoff
                                             NOx=nitrogen oxides
                                             VOC=volatile organic compounds
Source: GAO.

                                             Notes: Landing and takeoff data for U.S. aircraft in 2001 obtained from AvSoft. Emissions were
                                             calculated using FAA’s Emissions and Dispersion Modeling System, version 4.01. The following
                                             variables were assumed to be the same for all aircraft: (1) taxi-time: 15 minutes, (2) auxiliary power
                                             unit time: 26 minutes, and (3) ceiling height for emissions mixing with local air: 3,000 feet. The
                                             model’s default was used for takeoff weight.
                                             a
                                              Pounds of emissions per one landing/takeoff (LTO), which includes emissions for takeoff, climb to
                                             3,000 feet, approach, taxi, and auxiliary power unit.



                                             Table 9: Additional Information on Comparison of Older and Newest Model Boeing
                                             737 Landing/Takeoff Emissions

                                                                            Average emission per landing/takeoff
                                                                            Older Boeing 737     Newest Boeing737
                                                 Emission                           (pounds)               (pounds)                     Changes
                                                 Nitrogen oxides                        12.1                   17.8                  47% increase
                                                 Carbon monoxide                        16.8                   10.7                 37% decrease
                                                 Hydrocarbons                             1.2                    1.1                10% decrease
                                             Source: GAO.

                                             Notes: Landing and takeoff data for U.S. aircraft in 2001 obtained from AvSoft. Emissions were
                                             calculated using FAA’s Emissions and Dispersion Modeling System , version 4.01. The following
                                             variables were assumed to be the same for all aircraft: (1) taxi-time: 15 minutes, (2) auxiliary power
                                             unit time: 26 minutes, and (3) ceiling height for emissions mixing with local air: 3,000 feet. The
                                             model’s default was used for takeoff weight.




                                             Page 66                                               GAO-03-252 Aviation and the Environment
Appendix VII: Additional Information on Our
Analysis of Aircraft Emissions




The U.S. 2001 commercial fleet included 988 older Boeing 737s. They accounted for 17.6 percent of
this fleet’s landings and takeoffs and 13.4 percent of this fleet’s nitrogen oxides emissions during
landing and takeoffs. The U.S. 2001 commercial fleet included 449 newer Boeing 737s. They
accounted for 5.0 percent of this fleet’s landings and takeoffs and 5.5 percent of this fleet’s nitrogen
oxides emissions during landing and takeoffs. See table 2 also.



Table 10: Additional Information on Comparison of Boeing 747 and 777 Emissions
on a Per Aircraft Basis

                                 Emission per aircraft during
                                       landing/takeoff
                               Boeing 747-400 Boeing B777-200ER
 Emission                           (pounds)                (pounds)            Changes
 Nitrogen oxides                         103.5                 124.2 20 percent increase
 Carbon monoxide                          47.7                  30.4 36 percent decrease
 Hydrocarbons                              4.1                   2.4 41 percent decrease
Source: GAO.

Notes: Landing and takeoff data for U.S. aircraft in 2001 obtained from AvSoft. Emissions were
calculated using FAA’s Emissions and Dispersion Modeling System, version 4.01. The following
variables were assumed to be the same for all aircraft: (1) taxi-time: 15 minutes, (2) auxiliary power
unit time: 26 minutes, and (3) ceiling height for emissions mixing with local air: 3,000 feet. The
model’s default was used for takeoff weight. See table 3 also.

The Boeing B77-200ER data is the weighted average (based on 2001 landings and takeoffs) for three
different engines. The nitrogen oxides and other emission characteristics of these engines vary
significantly.

The 58 Boeing 747-400s in the 2001 U.S. fleet have PW4056 engines and average 361 seats per
aircraft. The 101 Boeing 777-200ERs in the 2001 U.S. fleet have the following engines: PW4090
(37 aircraft averaging 302 seats), GE90-90B (16 aircraft averaging 283 seats), and TRENT 892B-17
(48 aircraft averaging 249 seats). The three engine types for the Boeing 777-200ERs emit 138.6,
123.6, and 112.3 pounds of nitrogen oxides emissions per landing/takeoff, respectively.




Page 67                                               GAO-03-252 Aviation and the Environment
Appendix VII: Additional Information on Our
Analysis of Aircraft Emissions




Table 11: Comparison of Power, Engine Operating Pressures, and Nitrogen Oxides
Emissions for a Boeing 737-300 and Its Most Common Replacement

                                                      Older model      Newer model
                                                      B737-300         B737-700
 Engine variant:                                      CFM56 3B-1       CFM56 7B-22
 Power (thrust) per engine:                           89 kiloNewtons   101 kiloNewtons
 Engine operating pressure ratio:                     22.4             24.41
 Landing/takeoff nitrogen oxides emissions:           10.72 pounds     15.08 pounds
Source: GAO.

Notes: Aircraft engine emissions data obtained from ICAO. Calculations made using FAA’s Emissions
and Dispersion Modeling System, version 4.01. Landing/takeoff emission computations assume
typical conditions of 3,000 foot mixing height, 15-minute taxi, and 26 minute auxiliary power unit
usage and 122,000 pound takeoff weight. See table 5 also.

Other details:                                         B737-300         B737-700
Takeoff weight used for comparison:                    122,000 lbs.     22,000 lbs.
Average seat count:                                    131             137
Number in 2001 commercial fleet:                       380             118
Production years for U.S. fleet:                       1984-1997       1997-present
Percent of 2001 commercial fleet landings/takeoffs:    7.7%            2.0%
Other landing/takeoff emissions in pounds:
   Carbon monoxide improved 41%:                       19.20 lbs.      11.27 lbs.
   Hydrocarbons improved 1.5%:                         01.20 lbs.      01.18 lbs.




Page 68                                               GAO-03-252 Aviation and the Environment
              Appendix VIII: Comments from the National Aeronautics and Space Administration
Appendix VIII: Comments from the National
Aeronautics and Space Administration




              Page 69                                      GAO-03-252 Aviation and the Environment
                  Appendix IX: GAO Contacts and Staff
Appendix IX: GAO Contacts and Staff
                  Acknowledgments



Acknowledgments

                  Gerald L. Dillingham (202) 512-3650
GAO Contacts      Teresa Spisak (202) 512-3950


                  In addition to the individuals named above, Carolyn Boyce, Joyce Evans,
Staff             David Hooper, David Ireland, Art James, Jennifer Kim, Eileen Larence,
Acknowledgments   Edward Laughlin, Donna Leiss, Jena Sinkfield, Larry Thomas, and
                  Gail Traynham made key contributions to this report.




(540020)
                  Page 70                               GAO-03-252 Aviation and the Environment
                         The General Accounting Office, the audit, evaluation and investigative arm of
GAO’s Mission            Congress, exists to support Congress in meeting its constitutional responsibilities
                         and to help improve the performance and accountability of the federal
                         government for the American people. GAO examines the use of public funds;
                         evaluates federal programs and policies; and provides analyses,
                         recommendations, and other assistance to help Congress make informed
                         oversight, policy, and funding decisions. GAO’s commitment to good government
                         is reflected in its core values of accountability, integrity, and reliability.


                         The fastest and easiest way to obtain copies of GAO documents at no cost is
Obtaining Copies of      through the Internet. GAO’s Web site (www.gao.gov) contains abstracts and full-
GAO Reports and          text files of current reports and testimony and an expanding archive of older
                         products. The Web site features a search engine to help you locate documents
Testimony                using key words and phrases. You can print these documents in their entirety,
                         including charts and other graphics.
                         Each day, GAO issues a list of newly released reports, testimony, and
                         correspondence. GAO posts this list, known as “Today’s Reports,” on its Web site
                         daily. The list contains links to the full-text document files. To have GAO e-mail
                         this list to you every afternoon, go to www.gao.gov and select “Subscribe to daily
                         E-mail alert for newly released products” under the GAO Reports heading.


Order by Mail or Phone   The first copy of each printed report is free. Additional copies are $2 each. A
                         check or money order should be made out to the Superintendent of Documents.
                         GAO also accepts VISA and Mastercard. Orders for 100 or more copies mailed to a
                         single address are discounted 25 percent. Orders should be sent to:
                         U.S. General Accounting Office
                         441 G Street NW, Room LM
                         Washington, D.C. 20548
                         To order by Phone:     Voice:    (202) 512-6000
                                                TDD:      (202) 512-2537
                                                Fax:      (202) 512-6061


                         Contact:
To Report Fraud,
                         Web site: www.gao.gov/fraudnet/fraudnet.htm
Waste, and Abuse in      E-mail: fraudnet@gao.gov
Federal Programs         Automated answering system: (800) 424-5454 or (202) 512-7470


                         Jeff Nelligan, managing director, NelliganJ@gao.gov (202) 512-4800
Public Affairs           U.S. General Accounting Office, 441 G Street NW, Room 7149
                         Washington, D.C. 20548