Aviation and the Environment: NextGen and Research and Development Are Keys to Reducing Emissions and Their Impact on Health and Climate
Published: 2008-05-06T00:00:00

Fast Facts:

Highlights:
section_title: Why GAO Did This Study
paragraphs: Collaboration between the federal government and the aviation industry has led to reductions in aviation emissions, but growing air traffic has partially offset these reductions. The Federal Aviation Administration (FAA), together with the National Aeronautics and Space Administration (NASA), the Environmental Protection Agency (EPA), and others, is working to increase the efficiency, safety, and capacity of the national airspace system and at the same time reduce aviation emissions, in part, by transforming the current air traffic control system to the Next Generation Air Transportation System (NextGen). This effort involves new technologies and air traffic procedures that can reduce aviation emissions and incorporates research and development (R&D) on emissions-reduction technologies. Reducing aviation emissions is important both to minimize their adverse health and environmental effects and to alleviate public concerns about them that could constrain the expansion of airport infrastructure and aviation operations needed to meet demand. This testimony addresses (1) the scope and nature of aviation emissions, (2) the status of selected key federal efforts to reduce aviation emissions, and (3) next steps and challenges in reducing aviation emissions. The testimony updates prior GAO work with FAA data, literature reviews, and interviews with agency officials, industry and environmental stakeholders, and selected experts.
section_title: What GAO Found
paragraphs: Aviation contributes a modest but growing proportion of total U.S. emissions, and these emissions contribute to adverse health and environmental effects. Aircraft and airport operations, including those of service and passenger vehicles, emit ozone and other substances that contribute to local air pollution, as well as carbon dioxide and other greenhouse gases that contribute to climate change. EPA estimates that aviation emissions account for less than 1 percent of local air pollution nationwide and about 2.7 percent of U.S. greenhouse gas emissions, but these emissions are expected to grow as air traffic increases. Two key federal efforts, if implemented effectively, can help to reduce aviation emissions--NextGen initiatives in the near term and research and development over the longer term. For example, NextGen technologies and procedures, such as satellite-based navigation systems, should allow for more direct routing, which could improve fuel efficiency and reduce carbon dioxide emissions. Federal research and development efforts--led by FAA and NASA in collaboration with industry and academia--have achieved significant reductions in aircraft emissions through improved aircraft and engine technologies, and federal officials and aviation experts agree that such efforts are the most effective means of achieving further reductions in the longer term. Federal R&D on aviation emissions also focuses on improving the scientific understanding of aviation emissions and developing lower-emitting aviation fuels. Next steps in reducing aviation emissions include managing NextGen initiatives efficiently; deploying NextGen technologies and procedures as soon as practicable to realize their benefits, including lower emissions levels; and managing a decline in R&D funding, in part, by setting priorities for R&D on NextGen and emissions-reduction technologies. Challenges in reducing aviation emissions include designing aircraft that can simultaneously reduce noise and emissions of air pollutants and greenhouse gases; encouraging financially stressed airlines to purchase more fuel-efficient aircraft and emissions-reduction technologies; addressing the impact on airport expansion of more stringent EPA air quality standards and growing public concerns about the effects of aviation emissions; and responding to proposed domestic and international measures for reducing greenhouse gases that could affect the financial solvency and competitiveness of U.S. airlines.

section_title: Letter
paragraphs: I appreciate the opportunity to testify before you on aviation emissions,  one of the key sources of concern about the environmental effects of  aviation. Over the past 30 years, the federal government, the aviation  industry, and other private parties have worked collaboratively to achieve  steady reductions in aircraft emissions. Nevertheless, increases in air  traffic, which have enhanced the nation’s productivity and mobility, have  partially offset these reductions, as more flights have produced more  emissions and congestion has led to flight delays. According to the Federal  Aviation Administration (FAA), this growth in air traffic will continue,  with the number of flights increasing 20 percent by 2015 and 60 percent by  2030. In light of these developments, concerns about the environmental  effects of aviation emissions have persisted. Moreover, better scientific  understanding of the potential health effects of certain aviation emissions  and their contribution to climate change has intensified the public’s  concerns.
To accommodate the expected growth in air traffic, FAA is leading a  multipronged, multiagency effort to increase the efficiency, safety, and  capacity of the national airspace system. This effort includes transforming  the current air traffic control system into the Next Generation Air  Transportation System (NextGen) and will require airport and runway  expansion. The NextGen initiative incorporates research and development  (R&D) on emissions-reduction technologies, alternative fuels, and cleaner  and quieter air traffic management procedures. This R&D is necessary  both to meet anticipated domestic and international environmental  standards and to reduce the environmental impact of aviation. Meeting  environmental standards can limit the adverse effects of aviation  emissions on air quality and climate, and addressing public concerns about  aviation emissions is necessary to avoid constraints on the expansion of  aviation operations and airport infrastructure planned under NextGen.
Under the National Environmental Policy Act of 1969, agencies evaluate  the likely environmental effects of projects they are proposing using an  environmental assessment or, if the projects likely would significantly  affect the environment, a more detailed environmental impact statement.  FAA typically carries out one of these evaluations for federally financed  airport construction projects, including the construction of federally  subsidized runways. In addition, under the Clean Air Act’s conformity  provision, no federal agency may approve or provide financial assistance  for any activity that does not conform to an applicable state  implementation plan. Therefore, FAA must evaluate whether a proposed  federal action associated with an airport project conforms with the  applicable state implementation plan before approving or funding the  project. In addition, the Clean Air Act mandates standards for mobile  sources of emission, such as aircraft and the equipment that service them  at airports. EPA sets emissions standards for aircraft and has chosen to  adopt international emissions standards for aircraft set by the  International Civil Aviation Organization (ICAO).
As requested, my testimony today focuses on aviation emissions. It will  address the following questions: (1) What are the scope and nature of  aviation emissions? (2) What is the status of selected key federal efforts to  address aviation emissions? and (3) What are some next steps and major  challenges for the federal government, the aviation industry, and Congress  related to aviation emissions? My statement is based on previous GAO  reports updated with a synthesis of recent empirical literature and  interviews with officials from FAA, the National Aeronautics and Space  Administration (NASA), and the U.S. Environmental Protection Agency  (EPA); representatives of aviation industry and environmental  associations, and selected aviation emissions experts. We balanced the  selection of these experts to capture the views of the many different  groups involved in aviation emissions reduction efforts and NextGen. We  conducted our work from March to May 2008 in accordance with generally  accepted government auditing standards. Those standards require that we  plan and perform the study to obtain sufficient, appropriate evidence to  provide a reasonable basis for our findings and conclusions based on our  study objectives. We believe that the evidence obtained provides a  reasonable basis for our findings and conclusions based on our study  objectives.
subsections: section_title: Aviation’s Small but Growing Proportion of Total Emissions Contributes to Health and Environmental Effects
paragraphs: Aviation-related activities contribute to local air pollution and produce  greenhouse gases that cause climate change. Aircraft account for about 70  to 80 percent of aviation emissions, producing emissions that mainly affect  air quality below 3,000 feet and increase greenhouse gases at higher  altitudes. At ground level, airport operations, including those of motor  vehicles traveling to and from the airport, ground service equipment,  and stationary sources such as incinerators and boilers, also produce  emissions. Together, aircraft operations in the vicinity of the airport and  other airport sources produce emissions such as carbon monoxide, sulfur  oxides, particulate matter, nitrogen oxides, unburned hydrocarbons,  hazardous air pollutants, and ozone that contribute to air pollution. In  addition, these sources emit carbon dioxide and other greenhouse gases  that contribute to climate change, but aircraft operations in the upper  atmosphere are the primary source of aviation-related greenhouse gases.  Carbon dioxide is both the primary aircraft emission and the primary  contributor to climate change. It survives in the atmosphere for over 100  years. Furthermore, other gases and particles emitted by aircraft— including water vapor, nitrogen oxides, soot, contrails, and sulfate—can  also have an impact on climate, but the magnitude of this impact is  unknown, according to FAA. Figure 1 illustrates aviation’s impact on air  quality and climate.
Currently, aviation accounts for a small portion of air pollutants and  greenhouse gas emissions. Specifically, aviation emissions represent less  than 1 percent of air pollution nationwide, but their impact on air quality  could be higher in the vicinity of airports. In addition, aviation accounts  for about 2.7 percent of the total U.S. contribution of greenhouse gas  emissions, according to the Department of Transportation’s Center for  Climate Change and Environment. A 1999 study by the United Nations’  Intergovernmental Panel on Climate Change (IPCC) estimated that global  aircraft emissions generally accounted for approximately 3.5 percent of  the warming generated by human activity.
As air traffic increases, aviation’s contribution to air pollution and climate  change could also grow, despite ongoing improvements in fuel efficiency,  particularly if other sectors achieve significant reductions. In addition,  aviation’s impact on air quality is changing as more fuel-efficient, quieter  aircraft engines are placed in service. While new aircraft engine  technologies have reduced fuel consumption, noise, and emissions of most  pollutants, they have not achieved the same level of reductions in nitrogen  oxide emissions, which contribute to ozone formation. According to FAA,  nitrogen oxide emissions from aviation will increase by over 90 percent by  2025 without improvements in aircraft emissions technologies and air  traffic management, and emissions of other air pollutants will also  increase, as shown in figure 2. Additionally, aviation’s greenhouse gas  emissions and potential contribution to climate change is expected to  increase. IPCC has estimated that aircraft emissions are likely to grow by 3  percent per year, outpacing the emissions reductions achieved through  technological improvements. Furthermore, as emissions from other  sources decline, aviation’s contribution to climate change may become  proportionally larger, according to FAA. Alternative fuels are not yet  available in sufficient quantities for jet aircraft, as they are for some other  uses, and therefore aviation cannot yet adopt this approach to reduce its  greenhouse gas emissions (see discussion below on U.S. efforts to develop  alternative fuels for aviation).
Aviation emissions, like other combustible emissions, include pollutants  that affect health. While it is difficult to determine the health effects of  pollution from any one source, the nitrogen oxides produced by aircraft  engines contribute to the formation of ozone, the air pollutant of most  concern in the United States and other industrialized countries. Ozone has  been shown to aggravate respiratory ailments. A National Research  Council panel recently concluded that there is strong evidence that even  short-term exposure to ozone is likely to contribute to premature deaths of  people with asthma, heart disease, and other preexisting conditions. With  improvements in aircraft fuel efficiency and the expected resulting  increases in nitrogen oxide emissions, aviation’s contribution to ozone  formation may increase. In addition, aviation is associated with other air  pollutants, such as hazardous air pollutants, including benzene and  formaldehyde, and particulate matter, all of which can adversely affect  health. Data on emissions of hazardous air pollutants in the vicinity of  airports are limited, but EPA estimates that aviation’s production of these  pollutants is small relative to other sources, such as on-road vehicles.  Nevertheless, according to EPA, there is growing public concern about the  health effects of the hazardous air pollutants and particulate matter  associated with aviation emissions. See appendix I for more detailed  information on the health and environmental effects of aviation emissions.
Carbon dioxide and other greenhouse gas emissions from aircraft  operations in the atmosphere, together with ground-level aviation  emissions that gradually rise into the atmosphere, contribute to global  warming and climate change. IPCC’s most recent report documents  mounting evidence of global warming and projects the potential  catastrophic effects of climate change. As figure 6 shows, climate change  affects precipitation, sea levels, and winds as well as temperature, and  these changes in turn will increasingly affect economies and infrastructure  around the world.
section_title: Key Federal Efforts to Address Aviation Emissions Include Near-Term Operational Changes and Longer-Term R&D Initiatives
paragraphs: Two key federal efforts, if implemented effectively, can help to reduce  aviation emissions—near-term NextGen initiatives and an array of R&D  programs over the longer term to fully enable NextGen and to reduce  aircraft emissions. The NextGen initiatives are primarily intended to  improve the efficiency of the aviation system so that it can handle  expected increases in air traffic, but these initiatives can also help reduce  aviation emissions. In addition, the federal government, led by FAA and  NASA, has longer-term R&D programs in place to improve the scientific  understanding of the impact of aviation emissions in order to inform  decisions about emissions-reduction strategies, explore potential  emissions-reducing alternative fuels, and develop NextGen and aircraft  emissions-reduction technologies.
subsections: section_title: NextGen Initiatives Have the Potential to Help Reduce Emissions
paragraphs: Technologies and procedures that are being developed as part of NextGen  to improve the efficiency of flight operations can also reduce aircraft  emissions. According to FAA, the implementation of NextGen could  reduce greenhouse gas emissions from aircraft by up to 12 percent. One  NextGen technology, considered a centerpiece of NextGen, is the  Automatic Dependent Surveillance-Broadcast (ADS-B) satellite aircraft  navigation system. ADS-B is designed, along with other navigation  technologies, to enable more precise control of aircraft during en route  flight, approach, and descent. ADS-B will allow for closer and safer  separations between aircraft and more direct routing, which will improve  fuel efficiency and reduce carbon dioxide emissions. This improved  control will also facilitate the use of air traffic control procedures that will  reduce communities’ exposure to aviation emissions and noise. One such  procedure, Continuous Descent Arrivals (CDA), allows aircraft to remain  at cruise altitudes longer as they approach destination airports, use lower  power levels, and thereby lower emissions and noise during landings.  Figure 3 shows how CDA compares with the current step-down approach  to landing, in which aircraft make alternate short descents and forward  thrusts, which produce more emissions and noise than continuous  descents. A limited number of airports have already incorporated CDA  into their operations. For example, according to officials from Los Angeles  International Airport, nearly 25 percent of landings at their airport use  CDA procedures in one of the airport’s standard terminal approaches. In  addition, United Parcel Service plans to begin using a nighttime CDA  procedure, designed and tested at the Louisville International Airport, for  its hub operations.
Two closely associated NextGen initiatives, Area Navigation (RNAV) and  Required Navigation Performance (RNP), have the potential to modify the  environmental impact of aviation by providing enhanced navigational  capability to the pilot. RNAV equipment can compute an airplane’s  position, actual track, and ground speed, and then provide meaningful  information on the route of flight selected by the pilot. RNP will permit the  airplane to descend on a precise route that will allow it to avoid populated  areas, reduce its consumption of fuel, and lower its emissions of carbon  dioxide and nitrogen oxides. See figure 4. Currently, over 350 RNAV/RNP  procedures are available at 54 airports, including Dallas/Fort Worth, Miami  International, Washington Dulles, and Atlanta Hartsfield.
Still another NextGen initiative, High-Density Terminal and Airport  Operations, is intended to improve the efficiency of aircraft operations at  busy airports, and, in the process, reduce emissions. At high-density  airports, the demand for access to runways is high, and arrivals and  departures take place on multiple runways. The combination of arrivals,  departures, and taxiing operations may result in congestion, which in turn  produces delays, emissions, and noise as aircraft wait to take off and land.  Under the High-Density Terminal and Airport Operations initiative, which  FAA has just begun to implement, aircraft arriving and departing from  different directions would be assigned to multiple runways and safely  merged into continuous flows despite bad weather and low visibility. To  guarantee safe separation, these airports would need enhanced navigation  capabilities and controllers with access to increased automation. Under  this initiative, aircraft would also move more efficiently on the ground,  using procedures that are under development to reduce spacing and  separation requirements and improve the flow of air traffic into and out of  busy metropolitan airspace. More efficient aircraft movement would  increase fuel efficiency and reduce emissions and noise. Although the  implementation of this initiative is in the early stages, FAA has identified  the R&D needed to move it forward.
Technologies and procedures planned for NextGen should also help  improve the efficiency of flights between the United States and other  nations, further reducing emissions, particularly of greenhouse gases. A  test program scheduled to begin in the fall of 2008, known as the Atlantic  Interoperability Initiative to Reduce Emissions (AIRE), sponsored by FAA  and the European Commission, Boeing, and Airbus, will involve gate-to- gate testing of improved procedures on the airport surface, during  departures and arrivals, and while cruising over the ocean. Some of the  procedures to be tested will use technologies such as ADS-B. A similar  effort—the Asia and South Pacific Initiative to Reduce Emissions  (ASPIRE)—was launched earlier this year, involving the United States,  Australia, and New Zealand.
section_title: Federal R&D Focuses on Long-Term Approaches to Addressing Aviation Emissions
paragraphs: We have previously reported that the federal government and industry  have achieved significant reductions in some aircraft emissions, such as  carbon dioxide, through past R&D efforts, and federal officials and  aviation experts agree that such efforts are the most effective means of  achieving further reductions in the longer term. As part of the a national  plan for aeronautics R&D, issued by the White House Office of Science  and Technology Policy, the federal government supports a comprehensive  approach to R&D on aviation emissions that involves FAA, NASA, and  other federal agencies. According to FAA, this approach includes efforts to  improve the scientific understanding of the nature and impact of aviation  emissions and thereby inform the development of more fuel-efficient  aircraft, of alternative fuels that can reduce aircraft emissions, and of air  traffic management technologies that further improve the efficiency of  aviation operations. NASA, industry, and academia are important partners  in these efforts. Notably, however, the development of breakthrough  technologies, such as highly fuel-efficient aircraft engines that emit fewer  greenhouse gases and air pollutants, is expensive and can take a long time,  both to conduct the research and to implement the new technologies in  new aircraft designs and introduce these new aircraft into the fleet.  Successfully developing these technologies also requires the support and  cooperation of stakeholders throughout the aviation industry.
subsections: section_title: FAA Supports Research on Improving the Scientific Understanding of Aviation Emissions and on Alternative Fuels
paragraphs: Improving the scientific understanding of aviation emissions can help  guide the development of approaches to reducing emissions by improving  aircraft manufacturers’ and operators’ and policy makers’ ability to assess  the environmental benefits and costs of alternative policy measures. Such  an assessment can then lead to the selection of the alternative that will  achieve the greatest net environmental benefits. For example, one  technology might greatly increase fuel efficiency, but produce higher  nitrogen oxide emissions than another, somewhat less fuel-efficient  technology. Overall, a cost benefit analysis might indicate that the less  fuel-efficient technology would produce greater net benefits for the  environment.
FAA currently supports several recent federal efforts to better quantify  aviation emissions and their impact through improvements in emissions  measurement techniques and modeling capability. One of these efforts is  FAA’s Partnership for Air Transportation and Emissions Reduction  (PARTNER) Center of Excellence. Created in 2003, PARTNER carries on  what representatives of airlines, aircraft and engine manufacturers, and  experts in aviation environmental research have described as a robust  research portfolio. This portfolio includes efforts to measure aircraft  emissions and to assess the human health and welfare risks of aviation  emissions and noise. For example, researchers are developing an  integrated suite of three analytical tools—the Environmental Design  Space, the Aviation Environmental Design Tool, and the Aviation  Environmental Portfolio Management Tool – that can be used to identify  interrelationships between noise and emissions. Data from these three  tools, together with the Aviation Environmental Design tool being  developed by the Volpe National Transportation Systems Center and  others, will allow for assessing the benefits and costs of aviation  environmental policy options. Another R&D initiative, the Airport  Cooperative Research Program (ACRP), conducts applied research on  aviation emissions and other environmental issues facing airports. The  program is managed by the National Academies of Science through its  Transportation Research Board under a contract with FAA, which  provided $10 million for the program in both 2007 and 2008 and is seeking  to increase these investments through its reauthorization to specifically  focus on aviation environmental issues. Several of the emissions-related  projects undertaken through ACRP have concentrated on developing  methods to measure particulate matter and hazardous air pollutants at  airports in order to identify the sources of these pollutants and determine  whether their levels could have adverse health effects. FAA has also  developed an Aviation Emissions Characterization roadmap to provide a  systematic process to enhance understanding of aviation’s air quality  emissions, most notably particulate matter and hazardous air pollutants. In  addition, FAA, in conjunction with NASA and the National Oceanic and  Atmospheric Administration, launched the Aviation Climate Change  Research Initiative to develop the scientific understanding necessary for  informing efforts to limit or reduce aviation greenhouse gas emissions.
Another effort, the Commercial Aviation Alternative Fuels Initiative  (CAAFI), led by FAA, together with airlines, airports, and manufacturers,  is intended to identify and eventually develop alternative fuels for aviation  that could lower emissions of greenhouse gases, and other pollutants;  increase fuel efficiency; and reduce U.S. dependence on foreign oil. CAAFI  supports research on low-carbon fuel from sources such as plant oils,  algae, and biomass that are as safe as petroleum-based fuel and compare  favorably in terms of environmental impact. Part of the research will  involve assessing the environmental impact of alternative fuels to  determine whether their use could reduce emissions of pollutants that  affect climate and air quality. The research will also assess the impact of  producing these fuels on the overall carbon footprint. The CAAFI sponsors  have set goals for certifying a 50 percent synthetic fuel for aviation use in  2008, a 100 percent synthetic fuel for use by 2010, and a biofuel made from  renewable resources such as palm, soy, or algae oils. As part of CAAFI,  Virgin Atlantic Airlines, together with Boeing, has tested a blend of  kerosene (normal jet fuel) and biofuels in a flight from London to  Amsterdam, and Continental, in association with Boeing and jet engine  manufacturer General Electric, is planning a similar test in 2009.
section_title: NASA Conducts Fundamental Aeronautics R&D in Support of NextGen, Including Efforts That Can Help Lower Emissions
paragraphs: NASA has devoted a substantial portion of its aeronautical R&D program  to the development of technologies critical to the implementation of  NextGen, as well as new aircraft and engine technologies, both of which  can help reduce aviation emissions.
NASA has three main aeronautics research programs – Fundamental  Aeronautics, Aviation Safety, and Airspace Systems – each of which  contributes directly and substantially to NextGen. For example, the  Airspace Systems program supports research on air traffic management  technologies for NextGen, and the Fundamental Aeronautics program  focuses on removing environmental and performance barriers, such as  noise and emissions, that could constrain the capacity enhancements  needed to accommodate projected air traffic increases. Appendix II  describes in more detail how NASA’s aeronautics R&D programs support  the implementation of NextGen.
NASA also works with aircraft and aircraft engine manufacturers to  increase fuel efficiency and reduce emissions. Their efforts have  contributed to a number of advancements in aircraft engine and airframe  technology, and NASA’s R&D on emissions-reduction technologies  continues. NASA has set technology-level goals for reducing greenhouse  gases, nitrogen oxides, and noise, which have become part of the U.S.  National Aeronautics Plan. For example, the plan includes a goal for  developing technologies that could reduce nitrogen oxide emissions  during landings and takeoffs by 70 percent below the ICAO current  standard. The plan also sets a goal of increasing fuel efficiency (and  thereby decreasing greenhouse gases emissions) by 33 percent. These  technologies would be incorporated in the next generation of aircraft,  which NASA refers to as N+1, by 2015. However, as NASA officials note,  these goals must be viewed within the context that each of the goals can  be fully met only if it is the only goal. For example, the goal for reducing  nitrogen oxides can be fully achieved only at the expense of the goals for  lowering greenhouse gas emissions and noise, because it is technologically  challenging to design aircraft that can simultaneously reduce all of these  environmental impacts.
For the longer term (2020), NASA is focusing on developing tools and  technologies for use in the design of advanced hybrid-wing body aircraft,  the following generation of aircraft, or N+2. Emissions from these aircraft  would be in the range of 80 percent below the ICAO standard for nitrogen  oxide emissions during landings and takeoffs, and fuel consumption would  be 40 percent less than for current aircraft. The U.S. aircraft and engine  manufacturing industry has also set goals for reducing aircraft emissions  in the engines the industry plans to produce. According to the Aerospace  Industries Association, which represents this industry, its members have  set a goal of reducing carbon dioxide emissions by 15 percent in the next  generation of aircraft while continuing to significantly reduce nitrogen  oxide emissions and noise.
The development of aircraft technologies such as those that NASA is  currently working on to reduce emissions can take a long time, and it may  be years before the technologies are ready to be incorporated into new  aircraft designs. According to FAA, the development process generally  takes 12 to 20 years. For example, the latest Pratt and Whitney engine, the  geared turbofan, which is expected to achieve significant emissions and  noise reductions, took 20 years to develop.
section_title: Several Steps Can Be Taken to Help Reduce Aviation Emissions, but Challenges Remain to Be Addressed
paragraphs: Reducing aviation emissions includes steps that FAA and others can take  to move the implementation of NextGen forward and support R&D on  NextGen and emissions-reduction technologies, as well as technical,  financial, regulatory challenges facing the federal government, the aviation  industry, and Congress.
subsections: section_title: Expediting the Implementation of NextGen Can Help Reduce Aviation Emissions
paragraphs: Implementing NextGen expeditiously is essential to handle the projected  growth in air traffic efficiently and safely, and in so doing, help to reduce  aircraft emissions. Steps to advance NextGen’s implementation include  management improvements and the deployment of available NextGen  components.
subsections: section_title: Management Improvements Can Move NextGen Forward More Efficiently
paragraphs: Several management actions are important to advance the implementation of  NextGen. One such action is to establish a governance structure within FAA  that will move NextGen initiatives forward efficiently and effectively. FAA has  begun to establish a governance structure for NextGen, but it may not be  designed to give NextGen initiatives sufficient priority to ensure the system’s  full implementation by 2025. Specifically, FAA’s implementation plan for  NextGen is called the Operational Evolution Partnership (OEP). The manager  responsible for OEP is one of nine Vice Presidents who report to the Chief  Operating Officer (COO) of FAA’s Air Traffic Organization (ATO), who  reports directly to the FAA Administrator. While the manager responsible for  OEP is primarily responsible for implementing NextGen, other Vice  Presidents are responsible for NextGen-related activities in their designated  areas. In addition, the FAA managers responsible for airports and aviation  safety issues are Associate Administrators who report through the Deputy  FAA Administrator to the FAA Administrator. Some of the activities for which  these Associate Administrators are responsible are critical to NextGen’s  implementation, yet there is no direct line of authority between the OEP  manager and these activities.
Some congressional leaders and other stakeholders, including aviation  industry representatives and aviation experts, view FAA’s management  structure for NextGen as too diffuse. Some of the stakeholders have called for  the establishment of a position or NextGen program office that reports  directly to the FAA Administrator to ensure accountability for NextGen  results. These stakeholders have expressed frustration that a program as large  and important as NextGen does not follow the industry practice of having one  person with the authority to make key decisions. They point out that although  the COO is nominally in charge of NextGen, the COO must also manage  FAA’s day-to-day air traffic operations and may therefore not be able to  devote enough time and attention to managing NextGen. In addition, these  stakeholders note that many of NextGen’s capabilities span FAA operational  units whose heads are on the same organizational level as the head of OEP or  are outside ATO, and they believe that an office above OEP and these  operational units is needed. In prior work, we have found that programs can  be implemented most efficiently when managers are empowered to make  critical decisions and are held accountable for results.
Another management action is needed to help ensure that FAA acquires  the skills required for implementation, such as contract management and  systems integration skills. Because of the scope and complexity of the  NextGen implementation effort, FAA may not have the in-house expertise  to manage it without assistance. In November 2006, we recommended that  FAA examine its strengths and weaknesses and determine whether it has  the technical expertise and contract management expertise that will be  needed to define, implement, and integrate the numerous complex  programs inherent in the transition to NextGen. In response to our  recommendation, FAA has contracted with the National Academy of  Public Administration (NAPA) to determine the mix of skills and number  of skilled persons, such as technical personnel and program managers,  needed to implement the new OEP and to compare those requirements  with FAA’s current staff resources. In December 2007, NAPA provided  FAA with its report on the types of skills FAA will require to implement  NextGen, and it has undertaken a second part of the study that focuses on  identifying any skill gaps between FAA’s current staff and the staff that  would be required to implement NextGen. NAPA officials told us that  they expect to publish the findings of the second part of the study in the  summer of 2008. We believe this is a reasonable approach that should help  FAA begin to address this challenge as soon as possible. It may take  considerable time to select, hire, train, and integrate into the NextGen  initiative what could be a large number of staff. we found that  program managers at highly successful companies were empowered to decide whether  programs were ready to move forward and to resolve problems and implement solutions.  In addition, program managers were held accountable for their choices. (LSI)–that is, a prime contractor who would help to ensure that the  discrete systems used in NextGen will operate together and whose  responsibilities may include designing system solutions, developing  requirements, and selecting major system and subsystem contractors.  However, this approach would require careful oversight to ensure that the  government’s interests are protected and could pose significant project  management and oversight challenges for the Joint Planning and  Development Office (JPDO), the organization within FAA responsible for  planning NextGen, and for FAA.
section_title: Deploying Available NextGen Components Can Demonstrate Their Ability to Operate Together and Achieve Anticipated Efficiencies
paragraphs: Moving from planning to implementing some components of NextGen can  begin to demonstrate the potential of the system as well as reduce  congestion in some areas of the country, thereby also reducing emissions.  Many of the technologies and procedures planned for NextGen are already  available, and a few have been implemented individually, such as the CDA  procedures in use in Los Angeles and Louisville and ADS-B in Alaska.  However, the available technologies and procedures have not yet been  deployed simultaneously to demonstrate that they can be operated safely  as an integrated suite of technologies and procedures in the national  airspace system. Several stakeholders have suggested that FAA consider a  gradual rollout of NextGen technologies and procedures in a particular  area. For example ADS-B technologies, CDA and RNAV/RNP procedures,  and high-density airport operations could be deployed in a defined area of  the current system, possibly in sequence over time, to test their combined  use and demonstrate the safety of an integrated suite of NextGen  advancements. Such a graduated rollout is sometimes referred to as  “NextGen Lite.” FAA is currently considering a demonstration project in  Florida and Georgia, in which it, together with aviation equipment  manufacturers and municipalities, would use the NextGen capabilities of  ADS-B, RNAV, and RNP for on-demand air taxi fleet operations. As other  NextGen capabilities, such as System-Wide Information Management  (SWIM ), are deployed and as air taxi fleet operations move to other  airports and regions, the demonstration will be expanded to include those  new capabilities and other airports and regions. According to the airlines  and other stakeholders we interviewed, a demonstration of the successful  integration of NextGen capabilities and of efficiencies resulting from their  use would give the airlines an incentive to equip their aircraft with  NextGen technologies. They could then lower their costs by reducing their  fuel consumption and decrease the impact of their operations on the  environment. The findings from our research indicate that such regional or  targeted demonstrations could accelerate the delivery of NextGen benefits  while helping to ensure safe operations within the current system. In  addition, demonstrations can increase stakeholders’ confidence in the  overall NextGen initiative.
section_title: Resolving Aeronautics R&D Funding Issues Is a Further Step in Addressing Aviation Emissions
paragraphs: Federal funding for aeronautics research, the category that includes work  on aviation emissions, has declined over the past decade, particularly for  NASA, which historically provided most of the funding for this type of  research. NASA’s current aeronautics research budget is about half of  what it was in the mid-1990s. Moreover, the budget request for aeronautics  R&D for fiscal year 2009 is $447 million, or about 25 percent less than the  $594 million provided in fiscal year 2007. (See table 1.) According to  NASA, about $280 million of the proposed $447 million would contribute  to NextGen. In addition, according to NASA officials, a significant portion  of the funding for subsonic fixed-wing aircraft is directed toward  emissions-related research, and many other research efforts contribute  directly or indirectly to potential emissions-reduction technologies.
As its funding for aeronautics R&D has declined, NASA has emphasized  fundamental research, which serves as the basis for developing  technologies and tools that can later be integrated into aviation systems,  and has focused less on developmental and demonstration work. As a  result, NASA is now sometimes developing technologies to a lower  maturity level than in the past, and the technologies are less ready for  manufacturers to adopt them, resulting in a gap in the research needed to  bring technologies to a level where they can be transferred to industry for  further development. Failure to address this gap could postpone the  development of emissions-reduction technologies.
As a partial response to the gap, the administration has proposed some  additional funding for FAA that could be used to further develop NASA’s  and others’ emissions- and noise reduction technologies. Specifically,  FAA’s reauthorization proposal seeks $111 million through fiscal year 2011  for the CLEEN Engine and Airframe Technology Partnership, which FAA  officials said is intended to provide for earlier maturation of emissions and  noise technologies while NASA focuses on longer-term fundamental  research on noise and emissions. The CLEEN partnership, which is also  contained in the House’s FAA reauthorization bill, would create a  program for the development and maturation of certifiable engine and  airframe technologies for aircraft over the next 10 years which would  reduce aviation noise and emissions. The legislation would require the  FAA Administrator, in coordination with the NASA Administrator, to  establish objectives for developing aircraft technology outlined in the  legislation. The technology requested to be developed would increase  aircraft fuel efficiency enough to reduce greenhouse gas emissions by 25  percent relative to 1997 subsonic jet aircraft technology, and, without  increasing other gaseous or particle emissions, reduce takeoff-cycle  nitrogen oxide emissions by 50 percent relative to ICAO’s standard.  Although FAA’s reauthorization bill has not yet been enacted, the  administration’s proposed fiscal year 2009 budget includes $10 million for  the CLEEN program.
The CLEEN program would be a first step toward further maturing emissions  and noise reduction technologies, but experts agree that the proposed funding  is insufficient to achieve needed emissions reductions. While acknowledging  that CLEEN would help bridge the gap between NASA’s R&D and  manufacturers’ eventual incorporation of technologies into aircraft designs,  aeronautics industry representatives and experts we consulted said that the  program’s funding levels may not be sufficient to attain the goals specified in  the proposal. According to these experts, the proposed funding levels would  allow for the further development of one or possibly two projects. Moreover, in  one expert’s view, the funding for these projects may be sufficient only to  develop the technology to the level that achieves an emissions-reduction goal in  testing, not to the level required for the technology to be incorporated into a  new engine design. Nevertheless, according to FAA and some experts we  consulted, the CLEEN program amounts to a pilot project, and if it results in  the development of emissions-reduction technologies that can be introduced  into aircraft in the near future, it could lead to additional funding from the  government or industry for such efforts.
FAA and NASA have identified the R&D that is needed for NextGen, but have  not determined what needs to be done first, at what cost, to demonstrate and  integrate NextGen technologies into the national airspace system. Completing  this prioritization is critical to avoid spending limited funds on lower-priority  efforts or conducting work out of sequence. Once the identified R&D has  been prioritized and scheduled, cost estimates can be developed and funds  budgeted. Prioritizing research needs is an essential step in identifying the  resources required to undertake the research.
The European Union is investing substantially in R&D that can lead to  fuel-efficient, environmentally friendly aircraft. In February 2008, the  European Union announced the launch of the Clean Sky Joint Technology  Initiative, with total funding of $2.4 billion over 7 years—the European  Union’s largest-ever research program. The initiative establishes a Europe- wide partnership between industry, universities, and research centers and  aims to reduce aircraft emissions of carbon dioxide and nitrogen oxides by  up to 40 percent and aircraft noise levels by 20 decibels. According to  FAA, it is difficult to compare funding levels for U.S. and European R&D  efforts because of differences in program structures and funding  mechanisms, Nevertheless, foreign government investments of such  magnitude in R &D on environmentally beneficial technologies could  reduce the competitiveness of the U.S. aircraft manufacturing industry,  since greater investments are likely to lead to greater improvements in fuel  efficiency and keep U.S. aircraft manufacturers competitive in the global  economy as well as reducing aviation’s impact on the environment.
section_title: Reducing the Impact of Aviation Emissions Poses Technical, Financial, and Regulatory Challenges
paragraphs: Reducing aviation emissions will require technological advances, the  integration of lower-emitting aircraft and NextGen technologies into  airline fleets, and strengthened or possibly new regulations to improve air  quality and limit greenhouse gas emissions. Fulfilling these requirements  will pose challenges to aviation because of the technical difficulties  involved in developing technologies that can simultaneously address air  pollutants, greenhouse gases, and noise; constraints on the airline  industry’s resources to invest in new aircraft and technologies needed to  reduce emissions and remain competitive; and the impact that emissions  regulations can have on the aviation system’s expansion and the financial  health of the aviation industry.
subsections: section_title: Simultaneously Addressing Air Pollutants, Greenhouse Gases, and Noise from Aircraft Presents Technical Challenges
paragraphs: Although the aviation industry has made strides in lowering emissions, more  reductions are needed to keep pace with the projected growth in aviation, and  achieving these reductions will be technically challenging. NASA’s efforts to  improve jet engine designs illustrate this challenge: While new designs have  increased fuel efficiency, reduced most emissions, and lowered noise, they  have not achieved comparable reductions in nitrogen oxide emissions.  Nitrogen oxide emissions have increased because new aircraft engines  operate at higher temperatures, producing more power with less fuel and  lower carbon dioxide and carbon monoxide emissions, but also producing  higher nitrogen oxide emissions, particularly during landings and takeoffs,  when engine power settings are at their highest. It is during the  landing/takeoff cycle that nitrogen oxide emissions also have the greatest  impact on air quality. As discussed, nitrogen oxides contribute to ground-level  ozone formation. Similarly, as we noted in a report on NASA’s and FAA’s  aviation noise research earlier this year, it is technologically challenging to  design aircraft engines that simultaneously produce less noise and fewer  greenhouse gas and other emissions. Although it is possible to design such  engines, the reductions in greenhouse gases could be limited in engines that  produce substantially less noise. NASA and industry are working on  technologies to address these environmental trade-offs. For example, the  Pratt & Whitney geared turbo fan engine that we mentioned earlier is  expected to cut nitrogen oxide emissions in half while also improving fuel  efficiency and thereby lowering carbon dioxide emissions. Nevertheless, it  remains technologically challenging to design aircraft that can reduce one  environmental concern without increasing another.
In a 2004 report to Congress on aviation and the environment, FAA noted  that the interdependencies between various policy, technological, and  operational options for addressing the environmental impacts of aviation  and the full economic consequences of these options had not been  appropriately assessed. However, in recent years, FAA has made progress  in this area, including its sponsorship of the previously mentioned  PARTNER study on the interrelationships between noise and emissions.  This study can be used to assess the costs and benefits of aviation  environmental policy options.
section_title: The Financial Condition of the Airline Industry Creates a Challenge to Implementing Emissions-Reduction Technologies
paragraphs: Most U.S. airlines have stated that they plan to invest in aircraft and  technologies that can increase fuel efficiency and lower emissions, but in  the near term, integrating new aircraft into the fleet, or retrofitting aircraft  with technologies that can improve their operational efficiency, poses  financial challenges to the airline industry. Aircraft have an average  lifespan of about 30 years, and the airlines can take almost that entire  period to pay for an aircraft. The current fleet is, on average, about half as  many years old—11 years for wide-body aircraft, and 14 years for narrow- body aircraft—and therefore is expected to be in operation for many years  to come. In addition, the financial pressures facing many airlines make it  difficult for them to upgrade their fleets with new, state-of-the-art aircraft,  such as the Boeing 787 and Airbus A380, which are quieter and more fuel  efficient, emitting lower levels of greenhouse gases. Currently, U.S.  carriers have placed a small proportion (40, or less than 6 percent) of the  over 700 orders that Boeing officials say the company has received for its  787 model. Furthermore, no U.S. carriers have placed orders for the new  Airbus 380. These financial pressures also limit the airlines’ ability to equip  new and existing aircraft with NextGen technologies such as ADS-B that  can enable more efficient approaches and descents, resulting in lower  emissions levels. FAA estimates that it will cost the industry about $14  billion to equip aircraft to take full advantage of NextGen.
Delays by airlines in introducing more fuel-efficient, lower-emitting aircraft  into the U.S. fleet and in equipping or retrofitting the fleet with the  technologies necessary to operate NextGen could limit FAA’s ability to  efficiently manage the forecasted growth in air traffic. Without significant  reductions in emissions and noise around the nation’s airports, efforts to  expand their capacity could be stalled and the implementation of NextGen  delayed because of concerns about the impact of aviation emissions. As we  previously reported, offering operational advantages, such as preferred  takeoff and landing slots, to fuel-efficient, lower-emitting aircraft or aircraft  equipped with ADS-B could create incentives for the airlines to invest in the  necessary technologies. Similarly, as noted, deploying an integrated suite of  NextGen technologies and procedures in a particular region could create  incentives for carriers to equip their aircraft with NextGen technologies.
section_title: More Stringent Regulatory Standards Pose Challenges for Airport Expansion Projects
paragraphs: Concerns about the health effects of air pollutants have led to more stringent  air quality standards that could increase the costs or delay the  implementation of airport expansion projects. In recent years, EPA has been  implementing a more stringent standard for ozone emissions to better protect  the health of people exposed to it, and this standard could require more  airports to tighten controls on nitrogen oxides and some types of volatile  organic compounds that also contribute to ozone formation. Under the  current standard, 122 airports are located in areas that are designated as  nonattainment areas. This number includes 43 of the 50 busiest U.S.  commercial service airports. In March 2008, EPA further revised the ozone  standard, because new evidence demonstrated that exposure to ozone at  levels below the level of the current standard are associated with a broad  array of adverse health effects. This recent revision to the ozone standard  will increase the number of U.S. counties, and hence airports, that will be in  nonattainment. EPA estimated that the number of affected counties could  potentially grow from 104 to 345 nationwide. While the exact number of  airports that will be affected has not been officially determined at this time,  FAA estimates that a modest number of commercial service airports in  California, Arizona, Utah, Texas, Oklahoma, Arkansas, and along the gulf  coast to Florida will be in nonattainment areas for the revised 8-hour ozone  standard. According to EPA, any development project beginning in 2011 at  these airports would have to conform to the state implementation plan.
As communities gain more awareness of the health and environmental effects  of aviation emissions, opposition to airport expansion projects, which has  thus far focused primarily on aviation noise, could broaden to include  emissions. According to a California air quality official, many of the same  communities that have interacted with airports over aviation noise have more  recently recognized that they could also be affected by emissions from airport  sources. In Europe, concerns about the impact of aviation on air quality and  climate change have led to public demands for tighter control over aircraft  emissions, and these demands have hindered efforts to expand airports in  Birmingham, and London (Heathrow). Moreover, a plan to expand London’s  Stansted Airport was rejected because of concerns about climate change that  could result from additional emissions.
To minimize constraints on the future expansion of airport capacity stemming  from concerns about the health and environmental effects of aviation  emissions, it will be important for airports; the federal and state governments;  and the airline industry to work together to accurately characterize and  address these concerns and to take early action to mitigate emissions. As  noted, constraints on efforts to expand airports or aviation operations could  affect the future of aviation because the national airspace system cannot  expand as planned without a significant increase in airport capacity. The  doubling or tripling of air traffic that FAA expects in the coming decades  cannot occur without additional airports and runways.
section_title: Market-Based Initiatives to Reduce Aviation Emissions of Greenhouse Gases Could Pose Challenges for U.S. Airlines by Increasing Their Costs
paragraphs: Concerns about the environmental effects of greenhouse gas emissions  have grown steadily over the years, leading to national and international  efforts to limit them. In the  In the United States, EPA has not regulated greenhouse gas emissions;  however, Congress is taking steps to deal with climate change, some of which  could include market-based measures that would affect the aviation industry.  For example, several bills were introduced in the 110th Congress to initiate  cap and trade programs for greenhouse gas emissions None of these bills  would include aviation directly in a cap and trade program. However, some  could have indirect consequences for the aviation industry by, for example,  requiring fuel producers to purchase allowances through the system to cover  the greenhouse gas content of the fuel they sell to the aviation sector. The  cost of purchasing these allowances could be passed on to fuel consumers,  including airlines, raising the cost of jet fuel. Fuel is already the airline  industry’s largest cost. According to the Air Transport Association, cap and  trade programs that significantly increase airline fuel costs could have  significant consequences for the industry and such programs could make it  more difficult for carriers to pay for aircraft or technologies that would  reduce greenhouse gas emissions. As we have previously noted, cap and  trade programs can cost-effectively reduce emissions of greenhouse gases  such as carbon dioxide, especially when compared with other regulatory  programs. However, it is important that the impact of such measures on  various sectors of the economy, such as the aviation industry, be thoroughly  considered.
Internationally, ICAO has not set standards for aircraft carbon dioxide  emissions, but it has been working, with the support of FAA, other  government aviation authorities, and the aviation industry, to develop a  strategy for addressing the impact of aviation on climate change, among  several efforts to address climate change. For example, ICAO published a  manual for countries, Operational Opportunities to Minimize Fuel Use and  Reduce Emissions. In 2004, ICAO endorsed the development of an open  emissions trading system as one option countries might use and endorsed  draft guidance for member states on establishing the structural and legal  basis for aviation’s participation in a voluntary open trading system. The  guidance includes information on key elements of a trading system, such  as reporting, monitoring, and compliance, while encouraging flexibility to  the maximum extent possible. In adopting the guidance last fall at the  ICAO Assembly, all 190 Contracting States—with the exception of those in  the European Union—agreed that the inclusion of one country’s airlines in  another country’s emissions trading system should be based on mutual  consent between governments.
Consistent with the requirement to pursue reductions of greenhouse gas  emissions from international aviation through ICAO, some countries that  have included the aviation sector in their emissions trading systems or  other emissions-reduction efforts have, excluded international flights.  Consequently, these countries’ efforts will not affect U.S. airlines that fly  into their airports. The European Union (EU), however, is developing  legislation, which has not been finalized, that would include both domestic  and international aviation in an emissions trading scheme. As proposed,  the EU’s scheme would apply to air carriers flying within the EU and to  carriers, including U.S. carriers, flying into and out of EU airports in 2012.  For example, under the EU proposal, a U.S. airline’s emissions in domestic  airspace as well as over the high seas would require permits if a flight  landed or departed from an EU airport. Airlines whose aircraft emit  carbon dioxide at levels exceeding prescribed allowances would be  required to reduce their emissions or to purchase additional allowances.  Although the legislation seeks to include U.S. airlines within the emissions  trading scheme, FAA and industry stakeholders have argued that U.S.  carriers would not legally be subject to the legislation.
While the EU’s proposal to include international aviation in its emissions  trading system is intended to help forestall the potential catastrophic  effects of climate change, according to FAA and airlines, it will also affect  the aviation industry’s financial health. In particular, according to FAA and  airline and aircraft and engine manufacturing industry representatives, the  EU’s proposal could disadvantage U.S. airlines, which have older, less fuel- efficient fleets than their European competitors. Paying for emissions  credits could, according to U.S. airlines, also leave them with less money  for other purposes, including investing in newer, more fuel-efficient  aircraft and technologies to improve flight efficiency and reduce fuel  usage. Furthermore, according to U.S. carriers, the proposed trading  scheme unfairly penalizes the aviation sector because it lacks a readily  available non-carbon-based alternative fuel, whereas other sectors can use  alternative fuels to reduce their emissions.
The governments of many nations, including the United States, oppose the  European Union’s proposal to unilaterally include international aviation in  its emissions trading system because the proposed approach is not  consistent with ICAO guidance. Furthermore, such an approach could be  inconsistent with international aviation agreements and may not be  enforceable. According to FAA, the EU’s inclusion of aviation in its  emissions trading scheme violates the Chicago Convention on  International Civil Aviation and other international agreements. FAA  further notes that the EU proposal ignores differences in the U.S. and EU  aviation systems and ignores a performance-based approach in which  countries decide which measures are most appropriate for goals on  emissions. We are currently undertaking for this Subcommittee a study of  the EU emissions trading system and its potential impact on U.S. airlines,  and other issues relating to aviation and climate change.
Mr. Chairman, this concludes my prepared statement. I would be pleased  to respond to any questions that you or other Members of the  Subcommittee may have.
section_title: Contacts and Acknowledgments
paragraphs: For further information on this testimony, please contact Dr. Gerald L.  Dillingham at (202) 512-2834 or by email at dillinghamg@gao.gov.  Individuals making key contributions to this testimony include Ed  Laughlin, Lauren Calhoun, Bess Eisenstadt, Jim Geibel, Rosa Leung, Josh  Ormond, Richard Scott, and Larry Thomas.
section_title: Appendix I: Federal Agency Views on Health and Environmental Effects of Air Pollution
paragraphs: Lung function impairment, effects on exercise  performance, increased airway responsiveness,  increased susceptibility to respiratory infection,  increased hospital admissions and emergency room  visits, pulmonary inflammation, and lung structure  damage (long term).
Results from animal studies indicate that repeated  exposure to high levels of ozone for several months or  more can produce permanent structural damage in the  lungs. Ozone is also responsible for several billion  dollars of agricultural crop yield loss in the United  States each year.
Carbon monoxide  Most serious for those who suffer from cardiovascular  disease. Healthy individuals are also affected, but only  at higher levels of exposure. Exposure to elevated  carbon monoxide levels is associated with visual  impairment, reduced work capacity, reduced manual  dexterity, poor learning ability, and difficulty in  performing complex tasks.
Adverse health effects on animals similar to effects on  humans.
Lung irritation and lower resistance to respiratory  infections.
Acid rain, visibility degradation, particle formation.  Contributes toward ozone formation, and acts as a  greenhouse gas in the atmosphere and, therefore, may  contribute to climate change.
Particulate matter  Effects on breathing and respiratory systems, damage  to lung tissue, cancer, and premature death. The  elderly, children, and people with chronic lung disease,  influenza, or asthma, tend to be especially sensitive to  the effects of particulate matter.
Visibility degradation, damage to monuments and  buildings, safety concerns for aircraft from reduced  visibility.  .
Eye and respiratory tract irritation, headaches,  dizziness, visual disorders, and memory impairment.
Contribute to ozone formation, odors, and have some  damaging effect on buildings and plants.
Act as greenhouse gases in the atmosphere and,  therefore, may contribute to climate change. Contrails  and contrail-induced clouds produce warming effect  regionally where aircraft fly.
Breathing, respiratory illness, alterations in pulmonary  defenses, and aggravation of existing cardiovascular  disease.
Together, sulfur dioxide and nitrogen oxides are the  major precursors to acid rain, which is associated with  the acidification of lakes and streams, accelerated  corrosion of buildings and monuments, and reduced  visibility.
section_title: Appendix II: Examples of the National Aeronautics and Space Administration’s Research and Development Programs Supporting NextGen
paragraphs: Safety management procedures that can predict, rather than  respond to, safety risks, in a high density, complex operating  environment; research to support safety analysis, development of  advanced materials for continued airworthiness of aircraft, aircraft  system and equipage management; and adaptive aircraft control  systems to allow the crew and aircraft to recover from unsafe  conditions.
Under its Aviation Safety program, NASA research supports  development of Safety Management Systems to provide a  systematic approach to manage safety risks; integrates prediction  and mitigation of risks prior to aircraft accidents or incidents; and  shares safety-related information through programs such as the  Aviation Safety Analysis and Information Sharing program.
Improved air traffic management technologies to manage  airspace configuration, support increases in volume and  complexity of traffic demands, mitigate weather impacts, and  maintain safe and efficient operations at airports, decrease  runway incursions, and address wake vortex issues.
Under its Airspace Systems program, NASA research supports  development of variable separation standards based on aircraft  performance levels in the en route environment; trajectory-based  operations, traffic spacing, merging, metering, flexible terminal  airspace, and expanded airport access; technologies and  procedures for safe runway procedures in low-visibility conditions;  coordinated arrival/departure management; and mitigation of  weather and wake vortex issues.
Management of aviation growth to meet the complexity of  operations within the NextGen environment, regulation and  certification of new manned and unmanned aircraft, and  management of operations in an environmentally sound manner.
Under its Fundamental Aeronautics program, NASA research  supports development of improved performance for the next  generation of conventional subsonic aircraft, rotorcraft and  supersonic aircraft and develops methods for environmental  management system to measure and assess reductions in air  quality impact, noise, and emissions.
section_title: Related GAO Products
paragraphs: Aviation and the Environment: FAA’s and NASA’s Research and  Development Plans for Noise Reduction Are Aligned, but the Prospects of  Achieving Noise Reduction Goals Are Uncertain. GAO-08-384.  Washington, D.C.: February 15, 2008.
Aviation and the Environment: Impact of Aviation Noise on  Communities Presents Challenges for Airport Operations and Future  Growth of the National Airspace System. GAO-08-216T. Washington, D.C.:  October 24, 2007.
Climate Change: Agencies Should Develop Guidance for Addressing the  Effects on Federal Land and Water Resources. GAO-07-863. Washington,  D.C.: August 7, 2007.
Responses to Questions for the Record; Hearing on the Future of Air  Traffic Control Modernization. GAO-07-928R. Washington, D.C.: May 30,  2007.
Responses to Questions for the Record; Hearing on JPDO and the Next  Generation Air Transportation System: Status and Issues. GAO-07-918R.  Washington, D.C.: May 29, 2007.
Next Generation Air Transportation System: Status of the Transition to  the Future Air Traffic Control System. GAO-07-748T. Washington, D.C.:  May 9, 2007.
Joint Planning and Development Office: Progress and Key Issues in  Planning the Transition to the Next Generation Air Transportation  System. GAO-07-693T. Washington, D.C.: March 29, 2007.
Next Generation Air Transportation System: Progress and Challenges in  Planning and Implementing the Transformation of the National  Airspace System. GAO-07-649T. Washington, D.C.: March 22, 2007.
Next Generation Air Transportation System: Progress and Challenges  Associated with the Transformation of the National Airspace System.  GAO-07-25. Washington, D.C.: November 13, 2006.
Aviation and the Environment: Strategic Framework Needed to Address  Challenges Posed by Aircraft Emissions. GAO-03-252. Washington, D.C.:  February 28, 2003.
Aviation and the Environment: Transition to Quieter Aircraft Occurred  as Planned, but Concerns about Noise Persist. GAO-01-1053. Washington,  D.C.: September 28, 2001.
Aviation and the Environment: Aviation’s Effects on the Global  Atmosphere Are Potentially Significant and Expected to Grow.  GAO/RCED-00-57. Washington, D.C.: February 18, 2000.
Aviation and the Environment: Results from a Survey of the Nation’s 50  Busiest Airports. GAO/RCED-00-222. Washington, D.C.: August 30, 2000.
Aviation and the Environment: Airport Operations and Future Growth  Present Environmental Challenges. GAO/RCED-00-153. Washington, D.C.:  August 30, 2000.
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