This is the accessible text file for GAO report number GAO-08-216T 
entitled 'Aviation and the Environment: Impact of Aviation Noise on 
Communities Presents Challenges for Airport Operations and Future 
Growth of the National Airspace System' which was released on October 
25, 2007. 

This text file was formatted by the U.S. Government Accountability 
Office (GAO) to be accessible to users with visual impairments, as part 
of a longer term project to improve GAO products' accessibility. Every 
attempt has been made to maintain the structural and data integrity of 
the original printed product. Accessibility features, such as text 
descriptions of tables, consecutively numbered footnotes placed at the 
end of the file, and the text of agency comment letters, are provided 
but may not exactly duplicate the presentation or format of the printed 
version. The portable document format (PDF) file is an exact electronic 
replica of the printed version. We welcome your feedback. Please E-mail 
your comments regarding the contents or accessibility features of this 
document to 

This is a work of the U.S. government and is not subject to copyright 
protection in the United States. It may be reproduced and distributed 
in its entirety without further permission from GAO. 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. 


Before the Subcommittee on Aviation, Committee on Transportation and 
Infrastructure, House of Representatives: 

United States Government Accountability Office: 


For Release on Delivery Expected at 11:00 a.m. EDT: 

Wednesday, October 24, 2007: 

Aviation And The Environment: 

Impact of Aviation Noise on Communities Presents Challenges for Airport 
Operations and Future Growth of the National Airspace System: 

Statement of Gerald L. Dillingham, Ph.D. 

Director, Physical Infrastructure Issues: 

National Airspace System: 


GAO Highlights: 

Highlights of GAO-08-216T, a testimony before the Subcommittee on 
Aviation, Committee on Transportation and Infrastructure, House of 

Why GAO Did This Study:
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. 

What GAO Found: 

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 

Figure: Concept Design for the Silent Aircraft: 

This figure is a combination of two illustrations showing the concept 
design for silent aircraft. 

[See PDF for image] 

Source: Cambridge-MIT Institute. 

[End of figure] 

To view the full product, including the scope and methodology, click on 
[hyperlink, http://www.GAO-08-216T]. For more information, contact 
Gerald L. Dillingham at (202) 512-2834 or 

[End of section] 

Mr. Chairman and Members of the Subcommittee: 

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[Footnote 1] 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;[Footnote 2] 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 


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. Jet aircraft operations are the primary 
source of aviation noise, particularly during takeoffs and landings, 
and people's perceptions of aviation noise, which vary from one 
individual to another, can also influence communities' views on 
aviation noise. As a result, even comparatively low levels of noise 
exposure can create concerns in communities surrounding airports. More 
stringent standards for aviation noise--imposed through legislation and 
regulation and enabled by advances in technology--have, together with 
the airlines' response to the economic downturn following the terrorist 
attacks of September 11, 2001, led to the retirement or modification of 
older, noisier jet aircraft and their replacement with new, quieter jet 
aircraft. According to FAA, this change in the composition of the U.S. 
commercial fleet has been the most important factor in decreasing noise 
around airports. Local government decisions that allow communities to 
expand near airports may, however, erode the reductions in noise 
achieved through the introduction of quieter aircraft. FAA has issued 
guidance that discourages incompatible land uses, such as residences, 
schools, and hospitals, in areas with significant aviation noise, but 
communities face strong development pressures, and research suggests 
that federal land-use guidelines have had mixed results in deterring 
residential development in these areas. Finally, aircraft flight paths 
expose communities to aviation noise near airports, and changes in 
those flight paths may reduce or eliminate noise exposure in some 
communities and introduce or increase it in others. To date, FAA's 
airspace redesign projects, which are intended to improve safety and 
efficiency while reducing congestion and delays, have generally 
involved changes in flight paths above 10,000 feet and have not greatly 
affected community noise levels. A planned project in the New York/New 
Jersey/Philadelphia area would, however, involve changes to flight 
paths at lower levels and has led to expressions of concern from 
communities that could experience higher noise levels. 

A number of efforts are underway or planned to address the impact of 
aviation noise on communities. First, more stringent noise standards, 
which are significantly lower than the prior standards, are being 
implemented as new aircraft are being designed, built, and integrated 
into the U.S. commercial fleet. However, the implementation of these 
new standards may not have a significant impact on aviation noise 
levels because many aircraft in the current fleet met the new standards 
before they were required, the new aircraft will be integrated into the 
fleet over time, and increases in air traffic are likely to offset the 
reductions in noise levels attributable to quieter aircraft. Second, 
noise mitigation measures can reduce the impact of aviation noise on 
communities. These measures, which are typically carried out by 
airports and funded primarily through FAA's voluntary Part 150 Noise 
Compatibility program, include soundproofing buildings, acquiring noise-
sensitive properties, and relocating people. Nearly 300 airports have 
participated in the Part 150 program and have both received and raised 
billions of dollars for mitigation measures. New FAA guidance, which is 
scheduled for release at the end of 2007, and the proposed FAA 
reauthorization legislation would respectively facilitate and expand 
airports' noise mitigation options. Third, research has led to the 
development of technologies that have reduced aviation noise, and this 
research is continuing, although declines in federal funding may have 
slowed the pace of government efforts. Both the National Aeronautics 
and Space Administration (NASA) and FAA have sponsored aviation noise 
research, often in collaboration with industry or academia. Such 
collaboration, for example, has contributed to the development of a 
Boeing aircraft that is expected to produce 60 percent less noise than 
its predecessor. Fourth, the planning for NextGen includes an 
environmental focus because concerns about aviation noise and 
emissions, which will grow with the expected increase in air traffic, 
will constrain efforts to expand system capacity. New technologies are 
being designed to control aircraft more precisely during approach and 
descent, thereby enabling the use of procedures that will reduce 
communities' exposure to aviation noise and emissions. Fifth, at an 
airport's request, FAA can impose restrictions on the operation of 
certain types of aircraft to reduce the impact of noise in surrounding 
communities. Generally, however, airports and airlines negotiate such 
restrictions without involving FAA. Finally, airports are using 
additional studies of aviation activity, supplemental measures of the 
effects of exposure to aviation noise, and community outreach and 
education to respond to community concerns about aviation noise and 
gain support for projects to increase airports' safety and efficiency. 

Major challenges and next steps for reducing or mitigating the effects 
of aviation noise include technological advances, substantial funding 
from government and the aviation industry, and cooperation on land-use 
issues. In the future, as in the past, technological advances through 
research and development will be the key to reducing aviation noise, 
but the timing of future advances is uncertain. Furthermore, additional 
federal funding for noise reduction research and development programs 
may be difficult to obtain without shifting funds from other federal 
noise reduction efforts, such as the Part 150 program. For the 
airlines, equipping new and existing aircraft with the NextGen 
technologies that will reduce communities' exposure to aviation noise 
will also be challenging. FAA estimates that the costs of equipping the 
fleet to take full advantage of NextGen will be about $14 billion. Yet 
even with quieter aircraft and quieter and more efficient NextGen 
procedures, aviation noise will persist around airports, and 
incompatible land uses will pose challenges for airports and FAA. State 
and local officials can help to address these challenges through land- 
use planning and regulations that limit incompatible development, and 
FAA can complete and issue proposed guidance that will clarify the 
options available for airports to dispose of adjacent land previously 
purchased with federal grants to buffer surrounding communities from 
aviation noise. The options, which would require passage of the pending 
FAA reauthorization legislation, include selling the land and using the 
sale proceeds for environmental projects. Cooperation on land-use 
issues among officials at all levels of government and aviation 
stakeholders will also be necessary to reduce or mitigate aviation 
noise sufficiently to obtain public buy-in for the capacity enhancement 
projects that are critical to a safe and efficient national air 
transportation system. 

We provided a draft of this testimony to FAA and NASA for review and 
comment. The agencies generally agreed with the information presented 
and provided technical clarifications that we incorporated as 

Jet Aircraft Operations, Land Uses, and Aircraft Flight Paths Are Key 
Factors That Affect Communities' Level of Noise Exposure: 

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[Footnote 
3] day night level (DNL 65 dB) or greater[Footnote 4]--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. [Footnote 5] 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 

Aircraft Operations Are the Major Source of Aviation Noise: 

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.[Footnote 6] 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.[Footnote 7] Bills pending in both the House and the 
Senate[Footnote 8] 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[Footnote 9] 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[Footnote 10] 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. 

Figure 1: Trends in Aviation Noise Exposure and Enplanements: 

This is a chart showing trends in aviation noise exposure and 
enplanements. The number of people (in millions) is on the X axis, and 
the Y axis is the year. 

[See PDF for image] 

Source: FAA. 

[End of figure] 

Incompatible Land Use Exposes Communities to Aviation Noise and Erodes 
Gains in Noise Control Achieved through More Stringent Standards and 
Advances in Technology: 

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. 

Figure 2: Aerial Photo Overlaid with Color-shaded DNL Contours: 

This is figure is an an aerial photo with color-shaded contours, 
showing the level of volume emitted from aircraft. 

[See PDF for image] 

Source: Wyle Aviation Services. 

[End of figure] 

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,[Footnote 11] 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."[Footnote 12] 

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 

Airspace Redesign Initiatives May Change Some Communities' Exposure to 
Aviation Noise: 

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 

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 

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.[Footnote 13] We are 
currently reviewing the New York/New Jersey/Philadelphia airspace 
redesign at the request of this Subcommittee. 

A Number of Efforts Are Underway or Planned to Reduce the Impact of 
Aviation Noise: 

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. 

Implementation of More Stringent Noise Standards May Not Noticeably 
Reduce Current Noise Levels: 

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.[Footnote 14] 
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 

Noise Mitigation Programs Have Reduced Adverse Noise Effects, and 
Proposed Guidance and Proposed Legislation Would Support Further Noise 
Mitigation Efforts: 

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),[Footnote 15] 
which they must match to varying degrees, depending on their 
size.[Footnote 16] 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)[Footnote 17] 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.[Footnote 

Table 1: AIP and PFC Investments for Noise-Related Purposes through 
Fiscal Year 2007: 

Dollars in millions. 

AIP funds, fiscal years 1982-2007: Mitigation measures for residences; 
Funding: $1,903. 

AIP funds, fiscal years 1982-2007: Land acquisition; 
Funding: $2,170. 

AIP funds, fiscal years 1982-2007: Noise monitoring system; 
Funding: $170. 

AIP funds, fiscal years 1982-2007: Mitigation measures for public 
Funding: $703. 

AIP funds, fiscal years 1982-2007: Noise compatibility plan; 
Funding: $87. 

Total AIP funds; 
Funding: $5,033. 

PFC funds, fiscal years 1992-2007: Multiphase; 
Funding: $1,283. 

PFC funds, fiscal years 1992-2007: Land acquisition; 
Funding: $481. 

PFC funds, fiscal years 1992-2007: Soundproofing; 
Funding: $1,018. 

PFC funds, fiscal years 1992-2007: Monitoring; 
Funding: $31. 

PFC funds, fiscal years 1992-2007: Planning; 
Funding: $15. 

Total PFC funds; 
Funding: $2,828. 

Grand total; 
Funding: $7,861. 

Source: FAA. 

[End of table] 

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.[Footnote 19] 

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.[Footnote 20] 
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.[Footnote 21] 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[Footnote 22] and Senate[Footnote 23] 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[Footnote 24] 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. 

Past Research Has Significantly Advanced Noise Reduction Technologies, 
and Efforts Are Continuing, though Federal Funding Has Declined: 

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. 

Collaboration with Industry and Others Has Advanced Research on 
Aviation Noise: 

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.[Footnote 25] Sponsored by FAA, NASA 
and Transport Canada,[Footnote 26] 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: 

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.[Footnote 27] 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.[Footnote 28] 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[Footnote 29] 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). 

Figure 3: NASA Aeronautics Funding, Fiscal Years 1994-2007: 

This is a line graph showing NASA aeronautics funding between the 
fiscal years of 1994 and 2007. 

[See PDF for image] 

Source: Aerospace Industries Association. 

[End of figure] 

Legislative Proposals Would Increase Funding for Noise Reduction 
Technologies, and More Efficient Targeting Can Maximize Research 

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[Footnote 30] 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[Footnote 31] below Stage 3 standards and that 
could be implemented in the next generation of aircraft,[Footnote 32] 
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.[Footnote 33] 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). 

Figure 4: Concept Design for the Silent Aircraft: 

This figure is a combination of two illustrations showing the concept 
design for silent aircraft. 

[See PDF for image] 

Source: Cambridge-MIT Institute. 

[End of figure] 

Planning for NextGen Includes an Environmental Focus, and Technologies 
and Procedures Are Being Developed to Reduce Noise as well as Improve 

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[Footnote 34] 
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 

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. [Footnote 35] 

Figure 5: Comparison of CDA and Current Step-Down Approach: 

This is a line chart with illustration to show the comparison of the 
CDA and current step-down approach. 

[See PDF for image] 

Source: Naverus and AVTECH; and Art Explosion (clip art). 
Note: Continuous Descent Arrivals keep aircraft higher longer and then 
have them descend at near-idle power to touchdown. Optimal profiles are 
not always possible, especially at busy airports. 

[End of figure] 

Similarly, Area Navigation/Required Navigation Performance (RNP) 
procedures[Footnote 36] 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). 

Figure 6: Comparison of RNP and Current Step-down Approach: 

This is a line chart with illustration to show the comparison of the 
RNP and current step-down approach. 

[See PDF for image] 

Source: Naverus and AVTECH; Art Explosion (clip art). 

Note: An RNP approach path allows for idle-thrust, continuous descent 
instead of today's step-down approaches with vectors. RNP precision and 
curved-approach flexibility can shift flight paths to avoid populated 

[End of figure] 

Airport Restrictions on Aircraft Operations Offer Limited Relief from 
Aviation Noise: 

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. 

Airports Are Using Additional Studies, Supplemental Noise Metrics, and 
Community Outreach to Address Community Concerns about Aviation Noise: 

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[Footnote 37] 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[Footnote 38] 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). 

Figure 7: Levels of Noise Associated with Various Activities: 

This figure is a chart with illustrations showing levels of noise 
associated with various activities. 

[See PDF for image] 

Source: FAA, Art Explosion, and Corel Draw. 

[End of figure] 

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 the Impact of Aviation Noise Poses Challenges Involving 
Technology, Funding, and Cooperation on Land-use 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. 

Technological Advances through Research and Development Are Key to 
Future Aviation Noise Reduction: 

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,[Footnote 39] designing aircraft engines 
to minimize noise could increase fuel burn, which would release more 
carbon dioxide and other greenhouse gases into the atmosphere. 

Providing Funding for Research and Development and for Equipping the 
Fleet with NextGen Technologies Poses Challenges for Government and 

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. 

Managing Land Use for Compatibility with the Airport Environment 
Requires Cooperation among Stakeholders and Communities: 

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). 

Figure 8: Residential Exposure to Aviation Noise: 

This figure is a combination of two photos showing residences with 
aircraft flying overhead. 

[See PDF for image] 

Source: Nova Development (clip art). 

[End of figure] 

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 

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. 

Contact and Acknowledgments: 

For further information on this testimony, please contact Dr. Gerald L. 
Dillingham at (202) 512-2834 or 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. 

[End of section] 

Appendix I: U.S. Airports That Are among the Nation's 50 Busiest and Do 
Not Have a Part 150 Noise Mitigation Program: 

Table: U.S. Airports That Are among the Nation's 50 Busiest and Do Not 
Have a Part 150 Noise Mitigation Program: 

Airport: Boston-Logan International. 

Airport: Chicago-O'Hare International. 

Airport: Dallas-Fort Worth International. 

Airport: Dallas Love Field. 

Airport: Denver International. 

Airport: Gillespie Field (San Diego, CA). 

Airport: Houston-David Wayne Hooks. 

Airport: Houston-George Bush Intercontinental. 

Airport: John F. Kennedy International (New York, NY). 

Airport: John Wayne-Orange County. 

Airport: Miami International. 

Airport: Newark International. 

Airport: New York La Guardia. 

Airport: Phoenix Deer Valley. 

Airport: Phoenix Mesa Gateway. 

Airport: Van Nuys (Van Nuys, CA). 

Airport: Washington Dulles International. 

Source: FAA. 

[End of table] 

[End of section] 

Related GAO Products: 

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, 

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. 

[End of section] 


[1] H.R. 2881 and S. 1300. 

[2] See GAO, Aviation and the Environment: Airport Operations and 
Future Growth Present Environmental Challenges, GAO/RCED-00-153 
(Washington, D.C; Aug. 30, 2000). For this report GAO surveyed 
officials from the nation's 50 busiest commercial service airports to 
obtain their views on the key environmental concerns and challenges 
affecting airports' operations and future growth and to identify the 
efforts under way to address these concerns. 

[3] A decibel is a unit for expressing the relative intensity of sounds 
on a scale from zero for the average least perceptible sound to 130 for 
the average pain level. 

[4] The impact of aviation noise is usually analyzed in terms of the 
extent to which this noise annoys people by interfering with their 
normal activities, such as sleep, relaxation, speech, television 
viewing, and school and business operations. The generally accepted 
model for assessing the effects of long-term noise exposure assigns 
additional weight to sounds occurring at night (between 10:00 p.m. and 
7:00 a.m.), and when those sound levels exceed 65 decibels, individuals 
report a noticeable increase in annoyance. 

[5] These estimates reflect a revision in FAA's method of estimating 
the number of people exposed to significant aircraft noise. FAA 
previously estimated that the number of people exposed to significant 
noise in 2000 was about 500,000. 

[6] ICAO is an advisory organization affiliated with the United Nations 
that aims to promote the establishment of international civil aviation 
standards and recommended practices and procedures. FAA is the U.S. 
representative to ICAO. 

[7] Some older business class jets that do not meet Stage 3 standards 
are still in service. According to the Airports Council International- 
North America, these louder business jets pose a noise problem at some 
smaller airports. 

[8] H.R. 2881 and S. 1300. 

[9] 14 CFR Parts 36 and 91. 

[10] Under the Stage 4 standards, none of an aircraft's maximum noise 
levels at takeoff, flyover, and approach can exceed Stage 3 noise 
levels. Compliance with the standards is determined by subtracting an 
aircraft's maximum takeoff, flyover, and approach levels from the 
maximum permitted noise levels. The differences obtained are the noise 
limit margins, which are added together to determine what is termed the 
effective perceived noise (EPN). When the three margins are added 
together, the total must be 10 EPN dB or greater; and when any two of 
the margins are added together, the sum must be 2 EPN dB or greater. 

[11] FAA, Aviation and the Environment: A National Vision Statement, 
Framework for Goals and Recommended Actions (Washington, D.C.: December 

[12] Timothy F. LeDoux, Airports and Their Cities: The Effectiveness of 
Mitigating Noise Exposure through Land Use Planning, 1990-2000, Wyle 
Research Report WR 07-23, October 2007. 

[13] Environmental justice generally refers to efforts to identify and 
address the disproportionately high and adverse human health and 
environmental impacts on minority and low income populations. In 1994, 
President Clinton issued an executive order requiring all federal 
agencies to make environmental justice a priority. In accordance with 
the executive order, the U.S. Department of Transportation issued an 
Order on Environmental Justice upholding principles laid out in the 
National Environmental Policy Act and other federal statutes that 
ensure the social, economic and environmental welfare of low-income and 
minority communities, as well as their involvement in the environmental 
and transportation decision-making processes. 

[14] The other criteria for adopting new standards are that they must 
provide environmental benefits, be economically reasonable, and take 
the potential interrelationships between noise and emissions into 

[15] The AIP program provides federal funds for development projects at 
the entire range of the nation's 3,400 airports - from small general 
aviation airports to the very largest airports that handle several 
million passengers per year. 

[16] According to FAA, noise projects are eligible for 80 percent 
funding under AIP for large-and medium-hub airports and 95 percent 
funding at small, nonhub, general aviation, and reliever airports. 

[17] Passenger facility charges are fees airports can charge passengers 
to fund FAA-approved projects. Not all airports charge these fees. 

[18] According to FAA, noise projects are 100 percent eligible under 
PFC and airports can use PFC funds for the required match for AIP 

[19] 49 U.S.C. 47504 c (2) (D). 

[20] U.S. Department of Transportation, Office of the Inspector 
General, Audit of the Management of Land under Airport Noise 
Compatibility Programs (Washington, D.C.: Sept. 30, 2005). 

[21] Under current law, an airport that disposes of noise land acquired 
with AIP grant funds is required either to return a proportional amount 
of the sale proceeds to the Trust Fund or to reinvest that amount in a 
noise compatibility project at the airport. 

[22] FAA Reauthorization Act of 2007, House of Representatives Report 
110-331, 110th Congress 1st Session, Section 132, pg. 9, September 17, 

[23] Aviation Investment and Modernization Act of 2007, U.S. Senate, 
110th Congress 1st Session, Section 203, pg. 30, May, 2007. 

[24] An airport sponsor is the entity that owns the airport. For 
example, the City of Los Angeles is the sponsor for Los Angeles 
International Airport. 

[25] FAA Centers of Excellence are FAA partnerships with universities 
and affiliated industry associations and businesses throughout the 
country that conduct aviation research in a number of areas including 
advanced materials, aircraft noise and emissions, and airworthiness. 

[26] Transport Canada is the department within the government of Canada 
that is responsible for developing policies, regulations and services 
for the Canadian transportation system. 

[27] According to NASA, about $58 million this budget goes toward 
noise- related research for subsonic fixed-wing aircraft. 

[28] According to NASA. fundamental research includes(1) foundational 
research, which is the lowest level of the research pyramid on which 
advanced noise reduction technologies can be built; (2) discipline- 
level fundamental research, which includes the development of noise 
prediction methods that can be used to understand the potential for 
noise reduction of various concepts; (3) multidiscipline-level 
fundamental research, which includes studying the trade-offs between 
noise, emissions, and performance that must be understood in order the 
determine the performance characteristics of a new aircraft; and (4) 
system-level fundamental research, which includes explaining research 
issues when noise reduction technologies are integrated into a new 
aircraft and can include major wind tunnel tests. 

[29] The Aerospace Industries Association represents the nation's 
leading manufacturers and suppliers of civil, military, and business 
aircraft, helicopters, unmanned aerial vehicles, space systems, 
aircraft engines, missiles, material, and related components, 
equipment, services, and information technology. 

[30] CLEEN stands for continuous lower energy, emissions and noise. 

[31] See footnote 10. 

[32] The reductions would occur in aircraft that would replace such 
current aircraft as the Boeing 737 and Airbus A320. Reductions would be 
different for larger aircraft and regional jets. 

[33] The noise reductions NASA predicts would be achieved through the 
technologies it is researching would be achieved if noise reduction is 
the only goal. However, when other factors are considered, such as the 
need to reduce pollutants like nitrogen oxides, the noise reductions 
may be lower. 

[34] As noted, JPDO is the interagency office housed within FAA that is 
responsible for planning NextGen and coordinating the transition to 
this new system. A JPDO task team is responsible for researching, 
developing, implementing, and maintaining an environmental protection 
strategy for NextGen. 

[35] See John-Paul Clarke, et al., Partnership for Air Transportation 
and Emissions Reduction Development, Design, and Flight Test Evaluation 
of a Continuous Descent Approach Procedure for Nighttime Operation at 
Louisville International Airport (Cambridge, MA: Jan. 9, 2006). 

[36] Area Navigation/Required Navigation Performance procedures provide 
enhanced navigational capability to the pilot. Area Navigation 
equipment can compute the airplane's position, actual track, and ground 
speed, and then provide meaningful information relative to the route of 
flight selected by the pilot. A critical component of Required 
Navigation Performance is the ability of the navigation system to 
monitor the aircraft navigation system to monitor its achieved 
navigation performance and to identify for the pilot if an operational 
requirement is or is not being met during an operation. 

[37] The Federal Interagency Committee on Aviation Noise serves as a 
forum for debate over future research needs to better understand, 
predict, and control the effects of aviation noise, and to encourage 
new technical developments in these areas. Federal agencies represented 
on the committee include the Departments of Defense, Housing and Urban 
Development, the Interior, and Transportation; the U.S. Environmental 
Protection Agency; and NASA. 

[38] The Federal Interagency Committee on Noise was the predecessor of 
the Federal Interagency Committee on Aviation Noise. 

[39] See GAO, Aviation and the Environment: Strategic Framework Needed 
to Address Challenges Posed by Aircraft Emissions, GAO-03-252 
(Washington, D.C.: Feb. 28, 2003) 

GAO's Mission: 

The Government Accountability Office, the audit, evaluation, and 
investigative arm of Congress, exists to support Congress in meeting 
its constitutional responsibilities and to help improve the performance 
and accountability of the federal government for the American people. 
GAO examines the use of public funds; evaluates federal programs and 
policies; and provides analyses, recommendations, and other assistance 
to help Congress make informed oversight, policy, and funding 
decisions. GAO's commitment to good government is reflected in its core 
values of accountability, integrity, and reliability. 

Obtaining Copies of GAO Reports and Testimony: 

The fastest and easiest way to obtain copies of GAO documents at no 
cost is through GAO's Web site [hyperlink,]. Each 
weekday, GAO posts newly released reports, testimony, and 
correspondence on its Web site. To have GAO e-mail you a list of newly 
posted products every afternoon, go to [hyperlink,] 
and select "E-mail Updates." 

Order by Mail or Phone: 

The first copy of each printed report is free. Additional copies are $2 
each. A check or money order should be made out to the Superintendent 
of Documents. GAO also accepts VISA and Mastercard. Orders for 100 or 
more copies mailed to a single address are discounted 25 percent. 
Orders should be sent to: 

U.S. Government Accountability Office: 
441 G Street NW, Room LM: 
Washington, DC 20548: 

To order by Phone: 
Voice: (202) 512-6000: 
TDD: (202) 512-2537: 
Fax: (202) 512-6061: 

To Report Fraud, Waste, and Abuse in Federal Programs: 


Web site: [hyperlink,]: 
Automated answering system: (800) 424-5454 or (202) 512-7470: 

Congressional Relations: 

Gloria Jarmon, Managing Director, 
(202) 512-4400: 
U.S. Government Accountability Office: 
441 G Street NW, Room 7125: 
Washington, DC 20548: 

Public Affairs: 

Susan Becker, Acting Manager, 
(202) 512-4800: 
U.S. Government Accountability Office: 
441 G Street NW, Room 7149: 
Washington, DC 20548: