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. 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. 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. 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. 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. 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. 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. 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. 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. 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). 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). 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. 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. 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. 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. 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. 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. 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. Gillespie Field (San Diego, CA) John F. Kennedy International (New York, NY) Van Nuys (Van Nuys, CA) 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. This is a work of the U.S. government and is not subject to copyright protection in the United States. The published product may be reproduced and distributed in its entirety without further permission from GAO. However, because this work may contain copyrighted images or other material, permission from the copyright holder may be necessary if you wish to reproduce this material separately.

Summary: 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. 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.