Aviation and the Environment: Impact of Aviation Noise on Communities Presents Challenges for Airport Operations and Future Growth of the National Airspace System
Published: 2007-10-24T00:00:00

Fast Facts:

Highlights:
section_title: Why GAO Did This Study
paragraphs: To address projected increases in air traffic and current problems with aviation congestion and delays, the Joint Planning and Development Office (JPDO), an interagency organization within the Federal Aviation Administration (FAA), is working to plan and implement a new air traffic management system, known as the Next Generation Air Transportation System (NextGen). This effort involves implementing new technologies and air traffic control procedures, airspace redesign, and infrastructure developments, including new or expanded runways and airports. Community opposition is, however, a major challenge, largely because of concerns about aviation noise. As a result, according to JPDO, aviation noise will be a primary constraint on NextGen unless its effects can be managed and mitigated. GAO's requested testimony addresses (1) the key factors that affect communities' level of exposure to aviation noise, (2) the status of efforts to address the impact of aviation noise, and (3) major challenges and next steps for reducing and mitigating the effects of aviation noise. The testimony is based on prior GAO work (including a 2000 survey of the nation's 50 largest airports), updated with reviews of recent literature, FAA data and forecasts, and interviews with officials from FAA and the National Aeronautics and Space Administration (NASA), industry and community representatives, and aviation experts.
section_title: What GAO Found
paragraphs: Key factors affecting the level of aviation noise that communities are exposed to include jet aircraft operations, land uses around airports, and aircraft flight paths. With more stringent regulatory standards for aviation noise, enabled by advances in technology, aircraft operations have become quieter, but aviation noise is still a problem when communities allow incompatible land uses, such as residences, schools, and hospitals, near airports. Aircraft flight paths also expose communities to aviation noise, and airspace redesign efforts, which are intended to improve aviation system safety and efficiency, may expose some previously unaffected communities to noise, raising concerns in those communities about higher noise levels. A number of efforts are underway or planned to address the impact of aviation noise on communities. More stringent noise standards for aircraft have been implemented, billions of federal dollars have been spent to soundproof buildings around airports, federal and private funding for research and development has advanced technologies to reduce aviation noise, NextGen technologies and procedures are being planned and will contribute to reducing communities' exposure to noise, some airports have imposed restrictions on the operation of certain aircraft, and airports are reaching out to communities to address their concerns about aviation noise and gain support for projects to increase airports' safety and efficiency. Major challenges for reducing or mitigating the effects of aviation noise include continuing to make technological advances; obtaining substantial funding--from the federal government for NextGen in particular and from industry for equipping aircraft with new technologies--and cooperating on land-use issues. Next steps could include state and local actions to limit incompatible development, FAA's issuance of guidance related to the disposal of land acquired with federal funding for noise mitigation purposes, and the passage of legislative proposals that would address environmental issues, including the reduction of aviation noise. FAA and NASA officials generally agreed with the information presented in this testimony and provided technical clarifications that GAO incorporated.

section_title: Letter
paragraphs: I appreciate the opportunity to testify before you today on the issue of  aviation noise. As you know, air traffic has grown steadily over the past 5  years and is expected to continue growing, from 740 million air passengers  in fiscal year 2006 to nearly 1 billion in 2015. With this growth has come a  host of benefits and costs, from greater productivity and mobility for the  nation as a whole to increased air traffic congestion, flight delays, and  environmental issues, including aviation noise. To handle the forecasted  growth, the Joint Planning and Development Office (JPDO), an  interagency organization within the Department of Transportation’s  Federal Aviation Administration (FAA), is working to plan and implement  a new air traffic management system, the Next Generation Air  Transportation System (NextGen). Critical objectives for NextGen are to  improve the overall safety and increase the efficiency of the National  Airpspace System. Achieving these objectives for airports will involve the  implementation of new technologies and air traffic control procedures,  airspace redesigns, and infrastructure developments, including new or  expanded runways and airports. Community opposition to these  developments is, however, a major challenge, largely because of concerns  about aviation noise. According to JPDO’s 2007 Concept of Operations  document, “current operational trends show that environmental impacts . .  . will be the primary constraint on the capacity and flexibility of the  NextGen unless these impacts are managed and mitigated.” JDPO further  states that noise has been and will continue to be a primary area of  concern. Legislative proposals to reauthorize FAA include a number of  provisions designed to address aviation noise issues.
My testimony today addresses the following questions: (1) What are the  key factors that affect the level of aviation noise exposure for  communities? (2) What is the status of efforts to address the impact of  aviation noise on communities? (3) What are the major challenges and  next steps for reducing and mitigating the effects of aviation noise? My  statement is based on our previous reports on aviation and the  environment, one of which included a survey of the nation’s 50 largest  airports; a synthesis of recent empirical literature; current FAA data and  forecasts; published reports of selected airports’ noise abatement  initiatives and community-based aviation noise groups’ efforts; and  interviews with officials from FAA and the National Aeronautics and  Space Administration (NASA), representatives of aviation industry groups  and aircraft manufacturers, and selected aviation noise experts. We  conducted our work from September to October 2007 in accordance with  generally accepted government auditing standards.
subsections: section_title: Jet Aircraft Operations, Land Uses, and Aircraft Flight Paths Are Key Factors That Affect Communities’ Level of Noise Exposure
paragraphs: Noise is one of the most significant environmental impacts of aviation.  Although noise is present around virtually every airport in the country, the  problem is greatest near busy commercial airports served by large jet  aircraft. According to FAA, the retirement of older, louder aircraft and  ground-based noise-mitigation efforts over the past 35 years have reduced  by over 90 percent the number of people affected by significant aviation  noise levels—defined as a 65-decibel day night level (DNL 65 dB) or  greater—despite nationwide increases in population and air traffic. FAA’s  estimates indicate that from 2000 to 2006 alone, the number of people  affected by these noise levels dropped by more than a third, from about  780,000 to about 500,000.  Nevertheless, these half million people are still  exposed to significant aviation noise levels, and as communities expand  near airports just outside the highly exposed areas and as air traffic  increases, millions more are affected by lower levels of aviation noise.  Changes in aircraft flight paths can also affect communities’ exposure to  aviation noise, redirecting air traffic over some communities that were not  previously exposed and diverting it from others.
subsections: section_title: Aircraft Operations Are the Major Source of Aviation Noise
paragraphs: Both jet aircraft engines and jet airframes produce aviation noise during  aircraft operations, particularly during takeoffs and landings. Moreover,  certain types of aircraft contribute disproportionately to the level of noise  around airports. In our 2000 report on environmental concerns and  challenges for airports, we reported that the primary issue of concern  identified by officials of the nation’s 50 busiest airports was the noise  generated by older jet aircraft. With the implementation of technologies to  reduce aircraft engine noise, efforts to reduce noise from airframes will  become more important.
As technologies for reducing aviation noise have advanced (see our  discussion of some of these advances in the next section of this  testimony), regulatory standards for jet aircraft noise have become more  stringent. The Airport Noise and Capacity Act of 1990 authorized the  Secretary of Transportation to reduce aviation noise through a program to  phase out older, noisier aircraft – known as Stage 2 aircraft— by  December 31, 1999. Aircraft owners could either retire Stage 2 aircraft  weighing over 75,000 pounds or modify them with hushkits to sufficiently  muffle the noise they generated to meet Stage 3 standards. FAA had  adopted the Stage 3 standards in 1977, the year they were established by  the International Civil Aviation Organization (ICAO), and all aircraft  designed after that time were required to meet the Stage 3 standards, but  previously certified aircraft designs were grandfathered until the 1990 act  required that they be retired or modified. However, the act exempted  aircraft weighing less than 75,000 pounds, a category that includes older  business class jets. Stage 2 aircraft that weigh less than 75,000 pounds and  Stage 3 aircraft that have been recertified as such after being modified  with hushkits are in compliance with current standards, although these  aircraft tend to be louder than new aircraft in the same weight range. Bills  pending in both the House and the Senate would require, with certain  exceptions, that all existing aircraft meet Stage 3 standards, including  those aircraft under 75,000 pounds that are currently exempted. In  addition, in July 2005, FAA issued a Federal Aviation Regulation requiring  that all new jet aircraft designs be subject to the current, more stringent  ICAO noise standards, known as Stage 4. Specifically, any new aircraft  whose design was submitted to FAA for approval on or after January 1,  2006, must meet these standards, which are based on the Chapter 4  standards adopted by ICAO in 2001. The Stage 4 standards are 10 decibels  lower on a cumulative basis than the Stage 3 standards and represent a  significant reduction in noise.
Since 2001, substantial progress has been made in retiring older, noisier  aircraft. According to FAA, there has been a reduction of about 70 percent  in the number of registered aircraft that have been modified with  hushkits—mainly Boeing 727s and DC-9s. Today, there are 498 registered  hushkitted aircraft, which make up about 8 percent of the U.S. commercial  aircraft fleet. The replacement of these older aircraft with new, quieter  aircraft has been the most important factor in decreasing noise around  airports since the significant noise reductions achieved through the  phaseout of Stage 2 commercial aircraft, according to FAA. Figure 1  indicates that the number of people exposed to significant noise levels has  decreased even as the number of people flying has increased.
section_title: Incompatible Land Use Exposes Communities to Aviation Noise and Erodes Gains in Noise Control Achieved through More Stringent Standards and Advances in Technology
paragraphs: Decisions that allow communities to expand near airports may expose  residences, schools, hospitals, and other uses to aviation noise. Such  decisions are made primarily by local governments, but airports, which  cannot control development in the communities that surround them, may  nevertheless be held accountable by these communities for the effects of  aviation noise. Although the areas around airports exposed to significant  noise levels (DNL 65 dB or greater), known as noise contours (see fig. 2),  have shrunk with the retirement of older aircraft, the incompatible use of  land around airports remains a problem in dealing with the effects of  aviation noise. Some stakeholders have said that the gains that have been  made in noise attenuation through regulation and technology are being  eroded or threatened by incompatible land use.
FAA set the DNL 65 dB standard that is used to measure noise contours.  This standard reflects the level of noise exposure over time that FAA has  determined annoys people by interfering with normal activities such as  sleep, relaxation, school, and business operations. FAA has also issued  guidelines that identify land uses that would not be compatible with the  noise generated by a nearby airport’s operations, as well as land uses that  could successfully be located close to an airport without interfering with  their activity. Despite this guidance, however, strong pressure exists to  develop residential areas around heavily used airports, and despite the  steady decline in the number of people exposed to significant noise levels  (DNL 65 dB and above), large numbers of people are still exposed to at  least some noise around airports. And for FAA, population increases in  areas around airports that are exposed to even moderate amounts of  aviation noise pose a challenge because, given individuals’ varying  sensitivity to noise, even comparatively low levels of exposure can  generate community concerns. Population growth near airports also  creates challenges for airports when planning expansion projects to meet  the growing demand for air travel.
Any efforts to limit development have implications for the tax base of local  communities. As a result, as FAA noted in a 2004 report to Congress on  aviation and the environment, there is a disconnect between federal  aviation policy and local land-use decision-making. Until recently,  evidence about trends in land use incompatible with airport activity was  mostly anecdotal, but some empirical research is now available. For  example research sponsored by FAA and NASA shows that for 92  commercial airports, between 1990 and 2000, “the effectiveness of existing  federal land-use guidelines on reducing total noise exposure and deterring  residential development inside the DNL 65 dB contours is mixed.”  Moreover, according to the research, “land-use planning has done little to  address the increasing population aggregation on lands near existing noise  footprints.”
Furthermore, according to FAA, incompatible land use is emerging as a  problem around reliever airports, which predominantly service general  aviation traffic that would otherwise go to nearby busy airports. These  airports are located in quieter suburban and rural areas where aviation  noise is more noticeable. Local governments with jurisdiction over land- use planning and development continue to permit building near airports,  where developable land is comparatively plentiful. As a result,  communities that did not exist when some airports were built are now  opposing increases in aircraft operations and expansion at these airports.
section_title: Airspace Redesign Initiatives May Change Some Communities’ Exposure to Aviation Noise
paragraphs: The air traffic environment for the nation’s airspace was designed and  implemented in the 1960s and has undergone only minor changes over the  years. However, the use of the airspace has changed significantly, with  higher overall air traffic volumes and greater use of smaller and regional  jet aircraft. As discussed later in this statement, FAA’s airspace redesign  initiatives have the potential to improve safety and efficiency by allowing  the use of new arrival and departure procedures that can reduce the  impact of noise and emissions on nearby communities. At the same time,  though, they have led to concerns about aviation noise in some  communities that were not previously exposed to it.
Airspace redesign projects usually involve changes in aircraft arrival and  departure routes from airports. These changes may result in exposing  some communities to less noise and others to more noise. FAA has  completed over 30 airspace redesign projects, including projects around  major airports such as those serving Las Vegas, Dallas-Fort Worth,  Minneapolis, and Boston. According to FAA, between 2002 and 2007,  airspace redesign projects have produced almost $700 million in customer  benefits from reduced delays, more efficient routing, and reduced  restrictions attributable to a more balanced air traffic control workload.
Until recently, most airspace redesign projects have involved changes in  flight paths above 10,000 feet and have therefore not had a significant  impact on noise levels in communities near airports. However, FAA has  approved the most ambitious airspace redesign project to date, which  involves flight path changes in the New York/New Jersey/Philadelphia  airspace, including changes at levels below 10,000 feet. According to FAA,  this airspace is some of the most complex and congested anywhere in the  world, with about one third of the nation’s commercial air traffic passing  through it. Delays and congestion in this airspace or at area airports tend  to ripple throughout the system. Airspace redesign projects have the  potential to alleviate some of these problems at this critical chokepoint in  the national airspace system.
Because the airspace redesign for the New York/New Jersey/Philadelphia  area will make changes to arrival and departure routes, the noise contours  in the area will also change, exposing some communities to less noise and  others to more. According to FAA’s analysis of the effect of the redesign,  fewer people would be exposed to moderate to significant noise levels  than is currently the case, but some people who live under the new flight  paths would be exposed to higher though moderate levels of noise. On the  basis of this analysis, the environmental impact statement prepared for the  redesign project concludes that the project will not have a significant  environmental impact with respect to noise. However, the possible shift in  noise contours has led to significant expressions of concern, including  litigation in many of the communities that could experience higher though  moderate levels of aviation noise. One of these communities, which has a  large minority population, contends that the redesign would  disproportionately affect minority neighborhoods. This contention could  raise concerns about environmental justice. We are currently reviewing  the New York/New Jersey/Philadelphia airspace redesign at the request of  this Subcommittee.
section_title: A Number of Efforts Are Underway or Planned to Reduce the Impact of Aviation Noise
paragraphs: To reduce the impact of aviation noise, FAA, in conjunction with NASA,  aircraft and aircraft engine manufacturers, airlines, airports, and  communities, follows what the International Civil Aviation Organization  refers to as its “balanced approach.” This approach recognizes that short- term opportunities to mitigate the impact of aviation noise on  communities should be combined with longer-term efforts to reduce  aviation noise. Efforts include reducing noise at the source through more  stringent standards; implementing noise abatement programs in  communities near airports; supporting research and development  programs for new technologies to make aircraft quieter, developing and  implementing NextGen technologies and procedures, and restricting  aircraft operations . In addition, many airports address aviation noise  issues through studies, supplemental analyses, and community outreach.
subsections: section_title: Implementation of More Stringent Noise Standards May Not Noticeably Reduce Current Noise Levels
paragraphs: As aircraft whose design was approved on or after January 1, 2006, are  integrated into the fleet, the new Stage 4 noise standards will be  implemented. While these standards are more stringent than the prior  Stage 3 standards and have been adopted internationally as well as  domestically, their implementation may not have a significant impact on  aviation noise levels. According to the Airports Council International- North America, which represents many of the nation’s airports and other  stakeholders, the Stage 4 standards were already being met by a significant  proportion of the aircraft in production when ICAO adopted its identical  Chapter 4 standards in 2001. Additionally, aircraft manufacturers’ sales  forecasts indicate that most of the new aircraft coming into service in the  near future will be for the international market rather than for the U.S.  market.
During the discussions leading up to the adoption of the ICAO Chapter 4  standards, the European Union argued that more stringent noise limits  would push technology toward quieter aircraft. However, under the  current ICAO system, a key criterion for the adoption of new standards is  that they must be found to be “technologically feasible”—that is,  demonstrably capable of being introduced across a sufficient range of the  fleet, as shown by the commercial deployment or deployability of  technologies that can meet the specified noise reductions. Aviation  industry representatives indicated that they considered the ICAO process  rational for several reasons, including “not pushing the technology  envelope,” which could lead to a potential trade-off with aircraft  performance. Additionally, industry representatives have stated that new  product development programs are already complex and pose many  business and schedule risks. As a result, they believe it is inadvisable to  force more aggressive standards because they could lead to delays in new  programs. More recently, ICAO has formed independent review  committees under its Long Term Technology Goals initiatives to begin  discussions with stakeholders on technologies that might be available 10  to 20 years from now. These committees are not charged with developing  standards, but rather with involving stakeholders in these early  discussions and preparing a report based on these efforts that is designed  to stimulate further development of the most promising technologies and  better inform ICAO when new standards may need to be considered.
section_title: Noise Mitigation Programs Have Reduced Adverse Noise Effects, and Proposed Guidance and Proposed Legislation Would Support Further Noise Mitigation Efforts
paragraphs: Most airports are owned and operated by state governments and local  municipalities. Therefore, the primary responsibility for addressing  community concerns about noise resides with these entities. Nevertheless,  airports can reduce the impact of noise on surrounding communities by  undertaking measures to mitigate incompatible land use, such as acquiring  noise-sensitive properties, relocating people, modifying structures to  reduce noise, encouraging compatible zoning, and assisting in the sale of  affected properties.
FAA supports airports’ efforts to mitigate aviation noise through its  voluntary noise compatibility program, known as the Part 150 Noise  Compatibility Program, which provides guidance to airports on the types  of land uses that are incompatible with certain levels of airport noise and  encourages them to develop a noise compatibility program to reduce and  prevent such uses. As part of the process, airports map the area affected  by the noise and estimate the affected population. According to FAA,  mitigation measures, such as soundproofing homes, have brought relief to  tens of thousands of people in neighborhoods near long-established  airports since the early 1980s.
Airports that participate in the Part 150 program can receive noise set- aside funds from the Airport Improvement Program (AIP), which they  must match to varying degrees, depending on their size. According to  FAA, nearly 300 airports have participated in the program. These funds  can be used to, among other things, soundproof buildings and support  relocation by acquiring homes in areas with significant noise. Thirty five  percent of AIP discretionary funds are reserved for planning and  implementing noise compatibility programs. In fiscal year 2006, FAA  issued 90 noise-related AIP grants totaling $305 million.
Since the early 1980s, the federal government has issued grants or allowed  airports to impose charges to mitigate noise around many airports.  According to FAA, it has provided about $5 billion in AIP grants and  airports have used about $2.8 billion in passenger facilities charges (PFC)  for Part 150 noise mitigation studies and projects. In total, this funding  amounts to nearly $8 billion (see table 1). FAA officials further noted that  while the vast majority of airport noise mitigation projects use some AIP  or PFC funding, airports may undertake projects with other financing.
Although all airports are eligible to participate in the Part 150 program,  some of the busiest commercial airports do not. Among these are New  York’s JFK International and La Guardia, Newark International, Houston’s  George Bush Intercontinental, Dallas-Fort Worth International, Boston- Logan International, Dulles International, O’Hare International, and Miami  International (see app. I for a list of those airports among the 50 busiest  that do not participate in the Part 150 program). According to FAA, some  airports have chosen not to participate in the Part 150 program for a  variety of reasons. Some airport operators view the program as too  complicated, costly, and difficult to implement. FAA officials note that  some larger airports that have chosen not to participate in the program  may have such a significant number of incompatible land uses that it  would be financially prohibitive to implement mitigation measures in all  areas significantly affected by noise and that the projects that were  undertaken could take decades to complete. In addition, in some cases,  neighborhoods are so clustered together that mitigation measures would  have to be applied to a substantial number of homes outside significant  noise contours in order to establish equitable neighborhood boundaries.  FAA officials further note that an airport’s nonparticipation in the Part 150  program does not mean that the airport does not have an airport noise  mitigation program. For example, Boston Logan Airport has a noise  program that predates the Part 150 program and qualifies for federal noise  mitigation funding under the program through a grandfathering provision.  Airports can also use AIP discretionary grant and PFC funds for noise  mitigation without joining the Part 150 program. In addition, some  soundproofing of schools and healthcare facilities is eligible for federal  funding even if an airport does not participate in the Part 150 program.
Besides providing funding for airports’ noise mitigation efforts through the  Part 150 program, FAA published draft guidance in June 2007 on the  acquisition, management and disposal under AIP of noise land—that is,  land that is exposed to significant noise levels. The guidance initiative was  in part a response to the findings of an audit by the Department of  Transportation Inspector General of 11 airports that disposed of land  acquired for noise mitigation purposes. The audit found that each of the  11 airports had noise land acquired with AIP funds, ranging from nominal  acreage at several airports to hundreds of acres at others, that either was  no longer required for noise compatibility purposes or did not have a  documented need for airport development. The Inspector General  concluded that with improved oversight of noise land and its disposal,  FAA could recover an estimated $242 million for the Airport and Airways  Trust Fund, which provides most of the funding for aviation programs, or  for other airport noise mitigation projects. This finding was particularly  important in light of the constrained resources that are available for all  aviation programs. The final FAA guidance, which is scheduled for  issuance by the end of calendar year 2007, explains the current options for  reinvesting or transferring the proceeds from the sale of noise land  acquired under AIP, giving preference to investment in airport noise  compatibility projects. Provisions in the House and Senate  reauthorization proposals would authorize these options. These provisions  have the potential to help airports further mitigate the adverse effects of  the incompatible land uses around airports and could provide additional  resources for noise mitigation and other AIP-eligible investments.
The House reauthorization bill (H.R. 2881) also contains other provisions  that, if enacted, could enhance FAA’s and airports’ efforts to mitigate the  impact of noise on communities. Section 503 would allow FAA to accept  funds from airport sponsors to conduct special environmental studies to  support approved noise compatibility measures for federally funded  airport projects. In addition, Section 504 would allow FAA to accept funds,  including AIP grants and PFC funds, from a sponsor in order to hire staff  or obtain services to provide environmental reviews for new flight  procedures that have been approved for airport noise compatibility  purposes. Finally, Section 507 would authorize a new pilot program to  allow FAA to fund six environmental mitigation demonstration projects at  public-use airports to take previously laboratory-tested environmental  research concepts into the airport environment in order to determine if  they can measurably reduce or mitigate the environmental impacts of  aviation noise or emissions.
section_title: Past Research Has Significantly Advanced Noise Reduction Technologies, and Efforts Are Continuing, though Federal Funding Has Declined
paragraphs: Research and development of technologies for reducing aviation noise has  led to advancements that have significantly reduced the amount of noise  produced by aircraft, and this research continues, although further  advancements will be challenging. NASA, FAA, academic institutions, and  the aircraft and manufacturing industry are all involved in research and  development projects aimed at reducing aviation noise and its impacts.
subsections: section_title: Collaboration with Industry and Others Has Advanced Research on Aviation Noise
paragraphs: NASA, in partnership with the aircraft and aircraft engine manufacturing  industry, has contributed to a number of advancements in aircraft engine  and airframe technology that have substantially reduced the amount of  noise produced by aircraft and may lead to further reductions in the  future, depending on the extent to which current research leads to noise- reducing aircraft engine and airframe designs. For example, through  partnerships with industry, NASA has conducted research on engine noise  reduction technologies that have significantly reduced aviation noise.  Research on the use of composites has also enabled reductions in the  weight of aircraft, which affects the amount of noise the airframe  produces. As a result of these and other advancements, the newest aircraft  currently in production will produce substantially less noise than the  models they will replace. For example, Boeing estimates that the 787  aircraft will produce 60 percent less noise than the 767 and the noise from  the 747-800 will be 30 percent less than the 747-400 it is replacing.  Similarly, Airbus says that its new A-380 jumbo jet will produce 46 percent  less noise than the 747-400. However, industry representatives have  indicated that returns are diminishing from these types of improvements.
FAA conducts a significant amount of its research on aviation noise issues,  much of it through the Partnership for Air Transportation Noise and  Emission Reduction (PARTNER), the Department of Transportation’s  Volpe National Transportation Systems Center, and other entities.  PARTNER is a Center of Excellence that brings together experts from  government, academia, and industry. Sponsored by FAA, NASA and  Transport Canada, PARTNER includes 11 collaborating universities and  approximately 50 advisory board members who represent aerospace  manufacturers, airlines, airports, state and local governments, and  professional and community groups. The collaborating universities and  organizations represented on the advisory board provide equal matches  for federal funds for research and other activities. PARTNER projects  related to aviation noise involve testing alternative descent patterns;  identifying a means to reduce aircraft landing noise, fuel consumption, and  emissions; assessing the human health and welfare risks of aviation noise;  and developing online resources to better inform the public about aviation  noise issues. According to FAA, in the last 10 years, it has spent about $42  million on research to characterize noise and improve prediction methods,  including developing a capability to determine the trade-offs between  noise and emissions and quantifying the costs and benefits of various  mitigation strategies.
section_title: Federal Funding for Aviation Noise Research Has Declined
paragraphs: Federal funding for aviation noise research has declined over the past  decade, particularly for NASA, which provides most of the federal funding  for aeronautics research. NASA’s budget for aeronautics research has  dropped by about half over the past decade and is about $717 million for  fiscal year 2007. Partly to address this overall funding reduction, NASA  has reorganized its aeronautical research portfolio to focus on what it calls  “fundamental” research—a relatively early stage in the research and  development process that is less costly than the later stages. According to  FAA, the combination of a dramatic decrease in NASA’s funding and the  reorganization of its aeronautical research portfolio to focus on  fundamental research has left a gap in the near- and mid-term applied  research and development that could produce technological solutions  within the NextGen time frame.
According to FAA, most of the federal funding available for mitigating  aviation noise is targeted to sound insulation projects for buildings around  airports and relocation or acquisition programs. In a 2002 report on  reducing the environmental impacts of aviation, the National Research  Council’s Committee on Aeronautics Research and Technology for  Environmental Compatibility noted that the vast majority of federal  expenditures on aviation noise are allocated to noise abatement at  individual airports rather than to research on quieter aircraft and engines,  which would ultimately reduce aviation noise nationally and  internationally. The report concluded that the funding for federal research  programs was too low to remove noise as an impediment to the growth of  aviation—a conclusion that FAA reiterated in its 2004 report to Congress  on aviation and the environment. An analysis prepared by the Aerospace  Industries Association indicates that NASA’s aeronautics budget, which  includes funding for noise reduction research, has been declining in  constant dollars since the mid-1990s (see fig. 3).
FAA officials told us that both the Senate and the House reauthorization  proposals for FAA include several provisions for funding programs that  the authorizers believe will be critical to address the research gap. For  example, the CLEEN Engine and Airframe Technology Partnership would  create a program for the development, maturation, and certification of  engine and airframe technologies for aircraft over the next 10 years to  reduce aviation noise and emissions. FAA said that the program is  intended to provide some short-term advancement while NASA focuses on  longer-term research on noise and emissions.
NASA officials told us the agency has become more effective in targeting  its research resources to areas that have the most potential for success. In  particular, these officials cited work on significant noise-reducing  technologies that could be implemented in aircraft and engine designs as  early as 2015, depending on whether manufacturers take over  responsibility for integrating the new technologies into production-ready  aircraft. NASA has set goals for developing technologies that could reduce  what is known as effective perceived noise (EPN) by 42 EPN dB below  Stage 3 standards and that could be implemented in the next generation of  aircraft, which NASA refers to as N+1, by 2015 (N is the current  generation of advanced twin-engine aircraft). For the longer term (2020),  NASA is focusing on the development of tools and technologies that can  be used in the design of advanced hybrid wing body aircraft (N+2) and  that would achieve even greater noise reductions, in the range of 52 EPN  dB below Stage 3 standards. According to NASA, both of these research  efforts are also aimed at reducing emissions and fuel burn, which in  combination with noise reductions would help mitigate the environmental  effects of future increases in air traffic. NASA officials stress that because  NASA’s research ends at a relatively early stage of development, aircraft  and engine manufacturers would need to take over responsibility for  integrating the noise reduction improvements into aircraft and engine  designs, and their assumption of this responsibility is not guaranteed.  NASA and others in the aeronautics research community are working on  similar advanced designs, such as the “silent aircraft” concept that  involves researchers from Cambridge University in Great Britain and the  Massachusetts Institute of Technology (see fig. 4).
section_title: Planning for NextGen Includes an Environmental Focus, and Technologies and Procedures Are Being Developed to Reduce Noise as well as Improve Efficiency
paragraphs: Part of the planning for NextGen includes reducing the environmental  impact of aviation because concerns about aviation noise and emissions,  which will increase with the expected growth in air traffic, are strong  constraints on system capacity. A preliminary JPDO analysis shows that  noise and emissions could increase between 140 and 200 percent over the  next 20 years as a result of increased flights, which would become a  significant constraint on planned capacity improvements.
Technologies and procedures that are being developed as part of NextGen  to improve the efficiency of flight operations are also expected to help  reduce the impact of noise. One such technology, considered a  centerpiece of the NextGen system, is the Automatic Dependent  Surveillance–Broadcast (ADS-B) satellite aircraft navigational system.  ADS-B is designed, along with other navigation technologies, to provide  for more precise control of aircraft during approach and descent. This  improved control will facilitate the use of various air traffic control  procedures that will reduce communities’ exposure to aviation noise and  emissions. For example, the Continuous Descent Arrivals (CDA)  procedure (see fig. 5) is expected to allow aircraft to remain at cruise  altitudes longer as they approach destination airports, use lower power  levels, and thereby lower noise and emissions during landings. Under  current landing procedures, aircraft make step-down approaches that  alternate short descents and forward thrusts, which produce more noise  than a continuous descent. The PARTNER Center of Excellence has  designed and flight-tested a nighttime CDA procedure for the Louisville  International Airport, which United Parcel Service plans to begin using for  its hub operations in the near future.
Similarly, Area Navigation/Required Navigation Performance (RNP)  procedures will permit aircraft to descend on a precise route that will  allow them to avoid populated areas. FAA notes, however, that the new  procedures will not always be usable when traffic is heavy at busy airports  (see fig. 6).
section_title: Airport Restrictions on Aircraft Operations Offer Limited Relief from Aviation Noise
paragraphs: Airports can seek restrictions on the operations of certain types of aircraft  to reduce the impact of noise on surrounding communities. FAA  implements a national program for reviewing airport noise and access  restrictions, known as Part 161. Through this program, FAA reviews  airports’ requests to limit the operations of louder aircraft. According to  FAA, the Part 161 process has rarely been used since 2000. Only a few  airports have drafted Part 161 studies to support requests for restrictions,  and only one—Naples Airport in Florida—has fully completed the Part 161  process. Los Angeles International Airport and Bob Hope Airport in  Burbank, California, have indicated to FAA that they will be submitting  Part 161 studies to FAA to restrict the operations of certain aircraft that  meet the Stage 3 noise standards. FAA’s approval will be required for the  restrictions these airports are seeking. Because the Part 161 process  demands that airports submit studies showing, among other things, the  benefits of restricting aircraft operations, airport operators generally  choose to negotiate informal agreements with airlines rather than seek  mandatory restrictions. Airports have also imposed curfews on aircraft  operations in order to reduce the impact of noise in the early morning and  late evening. For example, at Reagan National Airport and San Diego  International Airport, louder aircraft are not allowed to land or take off in  the late evening and early morning.
section_title: Airports Are Using Additional Studies, Supplemental Noise Metrics, and Community Outreach to Address Community Concerns about Aviation Noise
paragraphs: According to FAA, communities are increasingly aware of efforts to plan  for and mitigate aviation noise, and complaints about noise are coming  increasingly from outside the DNL contours, along with demands for  action to address noise in areas outside significant noise contours. Some  community groups and the Environmental Protection Agency (EPA) have  questioned whether the DNL standard adequately captures the impact of  noise on people. FAA officials note that the Federal Interagency  Committee on Aviation Noise supports the use of the DNL measure and  that the use of the metric to measure noise near airports has been upheld  in court decisions. However, a number of airports have undertaken  additional measures, such as special noise studies, to respond to  community concerns about aviation noise.
According to some noise experts, the typical airport noise study presents  results only in terms of DNL contours on a background map, but very  rarely quantifies noise exposure with DNL or any other metric at specified  geographic locations in the study area. While DNL contours are used  effectively to establish land-use guidelines and define noise mitigation  program boundaries, they do not provide residents with practical  information about the aviation noise they will experience in their homes.  By contrast, the special noise studies not only enable residents to locate  their homes on a map that is overlaid with DNL contours, but they also  indicate how often airplanes fly overhead, at what time of day flights  occur, or how those flights may interfere with activities such as sleeping,  speaking, or watching television. According to the experts we spoke with,  the public has responded very positively to receiving this detailed  information about noise exposure.
With growing complaints about noise from outside the DNL contours,  airports are also contracting for analyses based on alternative noise  metrics to supplement the DNL noise analysis. Although the Federal  Interagency Committee on Noise in 1992 recommended continuing the  use of the DNL noise metric as the principal means of describing airport  noise exposure, it also recommended supplementing this description with  noise analyses based on alternative metrics. According to a leading  engineering firm that specializes in performing noise analyses, two  supplemental metrics are thought to define exposure in ways that the  general public can understand more readily than the DNL metric. One of  these metrics, the Number Above—which counts how many times noise  exceeds a selected threshold level in a given time period—has emerged as  the most useful supplemental metric, while another metric, Time Above— the total time that noise exceeds the threshold during the time period—is  also being used with increasing frequency. According to FAA officials,  FAA supports the use of supplemental metrics, noting that they may be  useful in evaluating some specific noise impacts, such as interference with  speech, sleep, and learning (see fig. 7).
Besides additional studies and supplemental noise metrics, airports are  using community outreach and education to address some of the impacts  of aviation noise. Representatives of airports and local governments we  spoke with emphasized that effective community outreach programs are  essential for addressing noise issues that arise when airports are planning  to expand or change their operations. One of these representatives noted  that early and continuous open communication between the airport, local  governments, and the affected communities is a key to gaining support for  projects to increase airport capacity. They pointed out that airports should  have ongoing efforts to seek stakeholder involvement on airport-related  issues and not wait until potential noise problems arise, such as when  airport expansion projects are being planned. For example, the San  Francisco International Airport has been bringing community  representatives and aviation officials together since 1981 to discuss and  attempt to resolve airport-related issues through the San Francisco  Roundtable—a voluntary body created by the airport that includes  representatives from 45 Bay Area jurisdictions, FAA officials, airline  advisers, air traffic managers, and the airport director. In addition,  according to a San Francisco International Airport official, the airport  reaches out to the community through its Managed Noise Mitigation  program, which encourages communities affected by airport noise to  determine their noise mitigation priorities and manage their distribution of  noise mitigation funds in accordance with their priorities. Other airports  have also made community outreach an important component of their  efforts to deal with the impacts of aviation noise. For instance, Chicago  established the O’Hare Noise Compatibility Commission in 1996 to begin  constructive dialogue on aircraft noise issues with the 40 communities  surrounding O’Hare International Airport. The commission’s community  outreach efforts include a Web site on aircraft noise issues; a community  outreach vehicle that travels to schools, libraries, and community events  and provides aircraft noise and noise-monitoring demonstrations; and a  quarterly newsletter that highlights the work of the commission and its  work to reduce noise at O’Hare.
To support airports’ community outreach efforts, the Transportation  Research Board (TRB) is undertaking a project that is intended to result in  guidance for airports on best practices in community outreach. According  to TRB, the project will identify the jurisdictions with authority over  various aspects of aviation noise and the obstacles to airport operations  and development that can occur because of surrounding communities’  negative perceptions about local aviation noise. The study will result in a  guidebook about local aviation noise that will allow airport decision  makers to manage expectations related to aviation noise within the  community. The study also includes alternative ways to communicate  noise issues and suggests other improvements that can help ease concerns  about aviation noise issues.
section_title: Reducing the Impact of Aviation Noise Poses Challenges Involving Technology, Funding, and Cooperation on Land- use Issues
paragraphs: Reducing aviation noise requires technological advances, substantial  funding from government and the aviation industry, and cooperation  among stakeholders and communities on land-use issues. Fulfilling these  requirements will be challenging because the pace of improvement in  existing technologies may have slowed, government and industry  resources are constrained, and land use involves strong competing  interests. While most of these challenges will take years to fully address,  steps can be taken now to help mitigate the impact of noise on  communities and reduce the constraints that noise can have on  transforming the air traffic system.
subsections: section_title: Technological Advances through Research and Development Are Key to Future Aviation Noise Reduction
paragraphs: The first challenge will be to continue reducing the amount of noise from  aircraft engines and airframes. NASA’s, FAA’s, and manufacturers’ past  research and development efforts have led to advances that have  significantly lowered aviation noise, but the timing of the next leaps in  technologies is uncertain. While NASA is conducting work on technologies  that it believes could, with industry support, lead to significant noise  reductions by 2015, FAA and aircraft industry representatives maintain  that, for some time, reductions in aircraft noise are likely to be  incremental. In addition, it may be technologically challenging to improve  the environment by reducing aviation noise without adversely affecting the  environment in other ways. As we reported in 2003, designing aircraft  engines to minimize noise could increase fuel burn, which would release  more carbon dioxide and other greenhouse gases into the atmosphere.
section_title: Providing Funding for Research and Development and for Equipping the Fleet with NextGen Technologies Poses Challenges for Government and Industry
paragraphs: Funding noise reduction research and development programs poses a  challenge for federal agencies. Given the federal government’s long-term  structural fiscal imbalance, additional funding for such programs may not  be available without shifting funds from other aviation noise reduction  efforts, such as programs to mitigate the impact of noise on communities.  Currently, most of the federal funding for reducing aviation noise goes to  soundproofing programs. Although funding for noise mitigation programs  may not generate the highest return on investments, reducing such funding  could make it more difficult to obtain community approval of airport  expansion projects necessary to increase system safety and efficiency.  Provisions in the Senate and House reauthorizations bills such as the  CLEEN proposal could help to address the challenges in this area, and  industry funding will continue to play an important role.
Implementing new noise reduction technologies, whether by integrating  new, quieter aircraft into the fleet or by retrofitting aircraft, poses financial  challenges for the aviation industry. Aircraft have an average lifespan of  about 30 years, and it can take almost that entire period for airlines 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 is therefore expected to be in operation for many years to  come. Additionally, the financial pressures facing many airlines make it  difficult for them to upgrade their fleets with new, quieter aircraft.  Currently, for example, U.S. carriers have placed a small proportion of the  over 700 orders (40, or less than 6 percent) that Boeing officials say the  company has received for its new state-of-the-art 787. These financial  pressures also have implications for airlines’ ability to equip new and  existing aircraft with NextGen technologies such as ADS-B that can enable  more efficient, quieter approaches and descents. FAA estimates that it will  cost the industry about $14 billion to equip aircraft to take full advantage  of NextGen. Congress and FAA may want to consider how to incentivize  the airlines to train their pilots and to equip and retrofit the fleet with the  technologies necessary to operate in NextGen as soon as possible.
section_title: Managing Land Use for Compatibility with the Airport Environment Requires Cooperation among Stakeholders and Communities
paragraphs: Even with the introduction of quieter aircraft and the implementation of  NextGen technologies and procedures that will enable quieter aircraft  approaches and landings, there will still be some noise around airports.  Additionally, these reductions in aviation noise are likely to be eroded by  the public’s increasing awareness of and sensitivity to even moderate  amounts of aviation noise and to predicted increases in the number of  aircraft flying overhead. Hence, incompatible land use will continue to  present obstacles to airport expansion projects. However, since most  airports are owned and managed by state or local authorities, it is  incumbent upon those authorities to work in good faith with FAA to  minimize incompatible land use in their jurisdictions (see fig. 8).
State and local authorities can take action, through land-use planning and  development, zoning, and housing regulation, to limit the use of land near  airports to purposes compatible with airport operations. State and local  governments could require, for example, that appropriate notice of airport  noise exposure be provided to purchasers of real estate and to prospective  residents near airports to ensure awareness of aviation noise issues. In  addition, FAA can make it easier for airports to dispose of AIP noise land  by completing and issuing its draft guidance on this process. Passing the  related provisions in the Senate and House FAA reauthorization bills will  also be important steps.
Thank you, Mr. Chairman and Members of the Subcommittee, this  concludes my prepared statement. I will be glad to answer any questions  that you may have at this time.
section_title: Contact and Acknowledgments
paragraphs: For further information on this testimony, please contact Dr. Gerald L.  Dillingham at (202) 512-2834 or dillinghamg@gao.gov. Individuals making  key contributions to this testimony include Ed Laughlin, Lauren Calhoun,  Bess Eisenstadt, Jim Geibel, David Hooper, Rosa Leung, Maureen Luna- Long, Josh Ormond, Jena Sinkfield, and Larry Thomas.
section_title: Appendix I: U.S. Airports That Are among the Nation’s 50 Busiest and Do Not Have a Part 150 Noise Mitigation Program
paragraphs: Gillespie Field (San Diego, CA)
John F. Kennedy International (New York, NY)
Van Nuys (Van Nuys, CA)
section_title: Related GAO Products
paragraphs: Airport Finance: Observations on Planned Airport Development Costs  and Funding Levels and the Administration’s Proposed Changes in the  Airport Improvement Program. GAO-07-885. Washington, D.C.: June 29,  2007.
Reagan National Airport: Update on Capacity to Handle Additional  Flights and Impact on Other Area Airports. GAO-07-352. Washington,  D.C.: February 28, 2007.
Aviation and the Environment: Strategic Framework Needed to Address  Challenges Posed by Aircraft Emissions. GAO-03-252. Washington, D.C.:  February, 28, 2003.
Aviation Infrastructure: Challenges Related to Building Runways and  Actions to Address Them. GAO-03-164. Washington, D.C.: January 30,  2003.
Aviation and the Environment: Airport Operations and Future Growth  Present Environmental Challenges. GAO/RCED-00-153, Washington, D.C.:  August 30, 2000.
Aviation and the Environment: Results from a Survey of the Nation’s 50  Busiest Commercial Service Airports. GAO/RCED-00-222. Washington,  D.C.: August 30, 2000.
Aviation and the Environment: FAA’s Role in Major Airport Noise  Programs. GAO/RCED-00-98. Washington, D.C.: April 28, 2000.
Reagan National Airport: Limited Opportunities to Improve Airlines’  Compliance with Noise Abatement Procedures. GAO/RCED-00-74.  Washington, D.C.: June 29, 2000.
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