Aviation and the Environment: FAA's Role in Major Airport Noise Programs
(Chapter Report, 04/28/2000, GAO/RCED-00-98).

Pursuant to a congressional request, GAO provided information on
airport-related noise, focusing on the: (1) types of projects that are
eligible for federally authorized funding to reduce airport-related
noise or mitigate its effects; (2) differences in the major methods for
measuring the impact of airport-related noise; (3) Federal Aviation
Administration's (FAA) noise standards for civil subsonic turbojets and
the reasons some of those aircraft are not required to comply with these
or earlier standards; and (4) status of FAA's Land Use Planning
Initiative and the major issues the initiative has raised about how best
to address airport-related noise.

GAO noted that: (1) most projects that reduce airport-related noise or
mitigate its impact are eligible for federally authorized funding; (2)
to be considered for funding under the Airport Improvement Program
(AIP), a project must be part of a FAA-approved noise compatibility
program; (3) in selecting which noise-related projects to fund, FAA
gives priority to projects affecting communities exposed to noise levels
of 65 decibels or higher, as determined by FAA's chosen measurement
method; (4) in contrast to projects funded by AIP, projects funded by
the Passenger Facility Charge program do not have to be part of a noise
compatibility program; (5) since the programs began, 75 percent of the
grants and over 50 percent of the passenger fees approved for
noise-related projects have been used to acquire land and soundproof
homes and other buildings; (6) the three principal methods for measuring
community exposure are mathematical calculations that differ in the
impact each places on noise from flights that occur during different
times of the day: (a) one method treats the impact of all flights
equally whenever they occur; (b) the second method differs from the
first by assigning greater impact to the noise from each flight that
occurs during the nighttime than to flights that occur during other
times; and (c) the third method assigns additional impact to evening
flights as well as nighttime flights; (7) noise standards for regulating
aircraft noise from civil subsonic turbojets are generally based on an
aircraft's weight and number of engines; (8) the heavier the aircraft
and the greater the number of engines, the more noise the aircraft is
allowed to generate and still comply with the required noise limits; (9)
the newest set of standards--stage 3 standards--apply to all aircraft
weighing more than 75,000 pounds and to newly manufactured aircraft
weighing 75,000 pounds or less; (10) these lighter aircraft did not have
to be retired under earlier noise standards because FAA concluded that
it was questionable whether the technology existed to modify those
aircraft in a cost-effective manner; (11) under its Initiative, FAA
announced five short-term actions in May 1999 designed primarily to
provide information that state and local governments can use to improve
the compatibility of land uses near airports; and (12) based on comments
provided by the aviation sector and the general public, there are four
principal areas of concern associated with the Initiative.

--------------------------- Indexing Terms -----------------------------

 REPORTNUM:  RCED-00-98
     TITLE:  Aviation and the Environment: FAA's Role in Major Airport
	     Noise Programs
      DATE:  04/28/2000
   SUBJECT:  Aircraft industry
	     Airports
	     Aircraft engines
	     Eligibility determinations
	     Federal/state relations
	     Federal aid for transportation
	     Standards and standardization
	     Land use agreements
	     Noise pollution control
IDENTIFIER:  Airport and Airway Trust Fund
	     FAA Airport Improvement Program
	     FAA Passenger Facility Charge Program
	     FAA Land Use Planning Initiative
	     FAA National Plan of Integrated Airport Systems
	     FAA Integrated Noise Model

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GAO/RCED-00-98

8

20

The Federal Role in Addressing Airport-Related Noise 20

Objectives, Scope, and Methodology 27

Broad, but Other Factors Affect Project Selection

30

Most Types of Projects Are Eligible for AIP, but They Generally Must
Be Part of an FAA-Approved Airport Noise Compatibility Program 30

Selection Criteria Influence Which Eligible Projects Receive AIP
Funding 31

The PFC Program Can Fund Some Project Costs Ineligible for AIP
Grants 33

Land Acquisition and Soundproofing Projects Receive the Majority
of AIP and PFC Noise-Related Funding 34

Information

39

Measuring Sound and Its Effects 39

Measures of Noise Identify Noise Levels of Single Aircraft Operations
and Community Exposure 41

FAA Selected the Day-Night Sound Level Method for Measuring Noise Exposure
52

Not Apply to Some Lighter Aircraft

54

Noise Standards Generally Permit Heavier Aircraft to Generate More
Noise Than Lighter Aircraft 54

Existing Aircraft Weighing 75,000 Pounds or Less Have Been Exempt
From Operating Restrictions 55

Improving Access to Information

59

FAA Facilitates State and Local Land Use Planning Efforts 59

Short-Term Actions Aim at Improving the Communication of
Information 60

Observations 65

Agency Comments 66

Appendix I: Process for Participating in the Part 150 Noise
Compatibility Program

70

Appendix II: National Priority System for AIP-Eligible Projects

75

Appendix III: Funding for Noise-Related Projects Through the
Airport Improvement Program, Fiscal Years 1982
Through 1999

77

Appendix IV: Funding for Noise-Related Projects Through the
Passenger Facility Charge Program, Fiscal Years 1992 Through 1999

86

Appendix V: Airport Model for Noise Measurement Method
Comparisons

89

Appendix VI: Comparisons of the Maximum Sound Levels and
Sound Exposure Levels for Four Aircraft

91

Appendix VII: Stage 3 Aircraft Noise Standards

93

Appendix VIII: FAA's Compatible Land Use Guidance

98

Appendix IX: Advisory Panel Members

101

Appendix X: GAO Contacts and Staff Acknowledgments

102

Table 1: Portions of AIP Funds Set Aside for Noise Mitigation
Projects, Fiscal Years 1982 Through 1999 25

Table 2: Typical Sound Levels of Common Occurrences 40

Table 3: Effects of Scheduling Changes on Noise Exposure Levels
Using Three Measurement Methods 49

Table 4: Time-Above Noise Measurements for 60 and 80 A-weighted Decibels 51

Table 5: Short-term Actions Under FAA's Land Use Planning
Initiative 61

Table 6: Summary of Key Land Use Planning Issues Related to
Airport Noise 64

Table 7: Point Values Assigned for Project Purpose in FAA's National
Priority System 75

Table 8: Point Values Assigned for Airport Size in FAA's National
Priority System 75

Table 9: Point Values Assigned for the Component Element in FAA's National
Priority System 76

Table 10: Point Values Assigned for Project Type in FAA's National
Priority System 76

Table 11: Noise-related Projects Funded Through the Airport
Improvement Program, Fiscal Years 1982 Through 1999,
by Project Type 77

Table 12: Noise-related Projects Funded Through the Passenger
Facility Charge Program, Fiscal Years 1992 Through 1999,
by Project Type 86

Table 13: Aircraft Selected for Airport Operations 90

Table 14: Compatible Land Use Table Based on FAA's Yearly
Day-Night Sound Level Measurements 99

Figure 1: Noise Contours at 65 and 60 Decibels for Three
Measurement Methods 14

Figure 2: AIP Noise-Related Projects, Fiscal Years 1982 Through
1999 (Total: $2.7 billion) 35

Figure 3: AIP Noise-Related Projects, Fiscal Years 1982 Through
1999 for Large Airports (Total: $2.1 billion) and for Small
Airports (Total: $582 million) 36

Figure 4: PFC Noise-Related Projects, Fiscal Years 1992 Through
1999 (Total: $1.6 billion) 37

Figure 5: PFC Noise-Related Projects, Fiscal Years 1992 Through
1999 for Large Airports (Total: $1.59 billion) and for Small
Airports (Total: $45.6 million) 38

Figure 6: Single Event Noise Levels Using the Maximum Sound
Level Method and the Sound Exposure Level Method,
Approach and Takeoff--Boeing 747 and C140 Aircraft 44

Figure 7: Noise Contours for Sound Equivalent Level, Day-Night
Sound Level, and Community Noise Equivalent Level Measurement Methods, at
75, 70, 65, 60, and 55 A-weighted Decibels 48

Figure 8: Part 150 Noise Exposure Map Preparation and Acceptance Process 71

Figure 9: Part 150 Noise Compatibility Program Preparation and
Approval Process 73

Figure 10: Maximum Sound Level and Sound Exposure Level for the
CL 600 and FAL 20 Aircraft 91

Figure 11: Maximum Sound Level and Sound Exposure Level for the Gulfstream
IV and MD 83 Aircraft 92

Figure 12: Noise Standards for Stage 3 Aircraft With Four or More
Engines--Takeoff 94

Figure 13: Noise Standards for Stage 3 Aircraft With Three or Fewer
Engines--Takeoff 95

Figure 14: Noise Standards for Stage 3 Aircraft Regardless of the
Number of Engines--Sideline 96

Figure 15: Noise Standards for Stage 3 Aircraft Regardless of the
Number of Engines--Approach 97

AIP Airport Improvement Program

FAA Federal Aviation Administration

GAO General Accounting Office

PFC Passenger Facility Charge

Resources, Community, and
Economic Development Division

B-283801

April 28, 2000

Congressional Requesters

In response to your request, this report discusses issues related to airport
noise, describing, in particular, (1) the eligibility of noise reduction and
mitigation projects for federally authorized funding, (2) methods for
measuring airport noise, (3) aircraft noise standards for civil subsonic
turbojets, and (4) the Federal Aviation Administration's Land Use Planing
Initiative, which was designed to facilitate state and local land use
planning for areas near airports.

As agreed with your offices, unless you publicly announce its contents
earlier, we plan no further distribution of this report until 14 days after
the date of this letter. At that time, we will send copies to the
appropriate congressional committees; the Honorable Rodney E. Slater,
Secretary of Transportation; and the Honorable Jane F. Garvey,
Administrator, Federal Aviation Administration. We will also make copies
available to other interested parties upon request.

If you or your staff have any questions about this report, please contact me
or Belva Martin, Assistant Director, at (202) 512-2834. Major contributors
to this report are listed in appendix X.
Gerald L. Dillingham, Ph.D
Associate Director, Transportation Issues

List of Requesters

The Honorable John J. Duncan, Jr.
Chairman
The Honorable William O. Lipinski
Ranking Democratic Member
Subcommittee on Aviation
Committee on Transportation and Infrastructure
House of Representatives

The Honorable Bob Franks
The Honorable Frank A. LoBiondo
The Honorable Robert Menendez
The Honorable William Pascrell, Jr.
The Honorable Steven R. Rothman
House of Representatives

Executive Summary

Since the late 1950s, noise from aircraft and other airport operations has
generated controversy with many surrounding communities and has emerged as a
constraint on airport development. New technology is making aircraft
quieter, but expected growth in air traffic may limit the net reduction in
overall noise levels generated by individual airports. The Federal Aviation
Administration (FAA) is responsible for several federal programs and
policies concerning airport-related noise and must consult with the
Environmental Protection Agency regarding some of its responsibilities. FAA
administers two programs that fund airports' capital development projects,
including noise-related projects: the Airport Improvement Program (AIP),
which is a federal grant program funded by appropriations from the Airport
and Airway Trust Fund, and the Passenger Facility Charge (PFC) program,
which allows airports to charge passengers a fee and retain these fees for
their use, subject to FAA approval. Together, these programs have recently
provided airports with about $3 billion a year; of that total, about $284
million was targeted in fiscal year 1999 for projects to reduce
airport-related noise or mitigate its effects. FAA is also responsible for
choosing the method used to measure the noise from airports and for
establishing standards that limit the noise that aircraft may generate.
Furthermore, FAA has recently embarked on a Land Use Planning Initiative to
help mitigate the effects of airport-related noise by facilitating state and
local land use planning for communities near airports.

Because of concerns about airport-related noise, the Subcommittee on
Aviation, House Committee on Transportation and Infrastructure, and several
Members of the House of Representatives asked GAO to determine (1) the types
of projects that are eligible for federally authorized funding to reduce
airport-related noise or mitigate its effects, (2) the differences in the
major methods for measuring the impact of airport-related noise, (3) FAA's
current noise standards for civil subsonic turbojets and the reasons some of
those aircraft are not required to comply with these or earlier standards,
and (4) the status of FAA's Land Use Planning Initiative and the major
issues the initiative has raised about how best to address airport-related
noise.

Airport-related noise emanates primarily from the takeoff and landing of
aircraft. Engine maintenance and the taxiing of aircraft on runways are
other activities that contribute to airport-related noise. The impact of
such noise on communities is usually analyzed in terms of the extent to
which the noise annoys people by interfering with their normal activities,
such as sleep, relaxation, speech, television, school, and business
operations. According to a 1978 study that has become the generally accepted
model for assessing the effects of long-term noise exposure, when sound
exposure levels are measured by the method that assigns additional weight to
sounds occurring at night (between 10 p.m. and 7 a.m.), and those sound
levels exceed 65 decibels, individuals report a noticeable increase in
annoyance.1

FAA implements several federal programs that address noise issues associated
with civilian airports.2 In addition to the AIP and PFC funding programs,
FAA administers an airport noise compatibility planning program, for which
it developed guidance on the types of land uses that are compatible or
incompatible with certain levels of airport-related noise. This program
encourages airports to identify nearby incompatible land uses and to develop
a program to reduce and prevent such uses. Under FAA's guidance for this
program, any land use is considered compatible where the average cumulative
airport-related noise level is below
65 decibels, when measured by the method that assigns additional weight to
sound from flights that occur at night. At noise exposure levels at or above
65 decibels, homes, schools, and hospitals are considered to be
incompatible, while other uses--such as heavy and light industry--are
considered compatible.

FAA has also been concerned that forecast growth in the demand for air
transportation will increase airport-related noise at some airports, even as
aircraft are becoming quieter. As a result, FAA has embarked on a Land Use
Planning Initiative to identify federal actions that could promote
compatible land use planning by states and localities. As part of that
initiative, FAA sponsored a special study to identify recommended actions,
and it requested comments and suggestions from the aviation community and
the general public.

Most projects that reduce airport-related noise or mitigate its impact--such
as soundproofing buildings--are eligible for federally authorized funding.
To be considered for funding under the Airport Improvement Program, however,
a project must, with a few exceptions, be part of an FAA-approved noise
compatibility program. In selecting which noise-related projects to fund,
FAA gives priority to projects affecting communities exposed to noise levels
of 65 decibels or higher, as determined by FAA's chosen measurement method.
FAA also gives priority to projects that rank higher than other projects on
the basis of factors such as airport size and project type. In contrast to
projects funded by the Airport Improvement Program, projects funded by the
Passenger Facility Charge program do not have to be part of a noise
compatibility program; also, under the Passenger Facility Charge program
airports set their own priorities for which noise-related projects they will
fund, subject to FAA approval. Since the programs began, 75 percent of the
grants and over 50 percent of the passenger fees approved for noise-related
projects have been used to acquire land and soundproof homes and other
buildings.

Measures of airport-related noise identify noise levels from a single
takeoff or landing or the average cumulative noise levels that communities
near airports are exposed to over time. Methods for measuring a single
takeoff or landing generally identify either the maximum sound level
generated by the event or the total sound of the event. Methods for
measuring the average cumulative noise levels that communities are exposed
to identify those geographic areas exposed to the same noise levels. The
three principal methods for measuring community exposure are mathematical
calculations that differ in the impact each places on noise from flights
that occur during different times of a day. One method treats the impact of
all flights equally whenever they occur; the second method differs from the
first by assigning greater impact to the noise from each flight that occurs
during the nighttime (10 p.m. to 7 a.m.) than to flights that occur during
other times; the third method assigns additional impact to evening flights
(flights between 7 p.m. and 10 p.m.) as well as to nighttime flights. In
response to a statutory directive to establish a single system for
determining the exposure of people to airport-related noise, FAA chose the
second method, which gives more weight to nighttime flights.

Noise standards for regulating aircraft noise from civil subsonic turbojets
are generally based on an aircraft's weight and number of engines.
Essentially, the heavier the aircraft and the greater the number of engines,
the more noise the aircraft is allowed to generate and still comply with the
required noise limits. For example, a four-engine aircraft weighing
212,500 pounds or more is allowed to make more noise on takeoff than a
lighter aircraft with the same number of engines. The standards allow
heavier aircraft to be noisier than lighter aircraft because aircraft noise
is generally determined by the thrust powering the aircraft--the heavier the
aircraft, the more thrust it needs. The newest set of standards--known as
stage 3 standards--apply to all aircraft weighing more than 75,000 pounds
and to newly manufactured aircraft weighing 75,000 pounds or less. The
Airport Noise and Capacity Act of 1990 mandated the retirement of heavier
aircraft not meeting stage 3 standards but not of aircraft weighing
75,000 pounds or less. These lighter aircraft also did not have to be
retired under earlier noise standards because FAA concluded that it was
questionable whether the technology existed to modify those aircraft in a
cost-effective manner.

Under its Land Use Planning Initiative, FAA announced five short-term
actions in May 1999 designed primarily to provide information that state and
local governments can use to improve the compatibility of land uses near
airports. For example, FAA created a website on the Internet to serve as an
information clearinghouse, and it plans to announce additional actions in
the future. Based on comments provided by the aviation sector and the
general public, there are four principal areas of concern associated with
the initiative. These four areas involve determining (1) the most effective
use of the agency's limited resources when addressing airport-related noise;
(2) whether the 65 decibel level defining incompatible land uses should be
lowered; (3) whether additional information, such as single event noise
levels, should be required when analyzing noise impacts; and (4) the best
use of federally authorized investment in the growth of airport capacity in
view of noise and physical expansion constraints at many airports.

FAA Policies Affect Project Selection for Grants

Most kinds of projects that reduce airport-related noise or mitigate its
impact on surrounding communities are eligible for funds through the AIP and
the PFC program. The types of projects eligible include such things as
acquiring homes and relocating people, soundproofing homes and other
buildings, and constructing noise barriers. However, federal statutes
governing the AIP (1) place some restrictions on the use of grant funds to
acquire land and (2) with a few exceptions, require that projects be part of
an FAA-approved noise compatibility program in order to be eligible for AIP
funds. Federal appropriations law prohibits the use of AIP funds for
studies, maps, or environmental impact analyses needed to implement flight
procedure changes made to reduce noise because these costs are paid for by
other appropriated funds for air traffic control. Furthermore, FAA policy
prohibits approving projects in airport noise compatibility programs if the
project provides remedial noise mitigation for new buildings that were known
to be incompatible with prevailing noise levels before they were built.

To select which eligible projects will receive AIP funding, the agency sets
priorities for eligible projects in two ways: (1) by giving priority, among
noise-related projects, to projects in communities exposed to average
cumulative noise levels of 65 decibels or higher and (2) by comparatively
ranking all AIP-eligible projects, including noise-related projects, on the
basis of several factors. The comparative ranking of projects is based on a
formula that assigns a numerical score to projects on the basis of factors
such as project type and airport size. For example, more points are given
for projects that increase safety and security than for noise mitigation
projects, and more points are given for projects at larger airports than for
projects at smaller airports. FAA also considers qualitative factors, such
as state and local airport plans and airport growth, in determining a
project's final ranking.

FAA officials stated that FAA has applied an annual cap on the amount of AIP
grants approved for noise-related projects at a single airport--
$5 million for noise mitigation projects and $3 million for insulating
public buildings used primarily for educational or medical purposes. The
administrative caps are imposed when the demand for funds set aside for
airport-related noise projects exceeds the amount available and are intended
to ensure that all airports that need funding for noise projects have access
to AIP funds.

The PFC program is a voluntary program that provides commercial service
airports with a more flexible funding source than the AIP. In addition to
paying for the types of projects eligible for AIP grants, PFC funds may pay
project financing costs, and projects do not have to be part of a noise
compatibility program. Airports can set their own priorities for project
funding, subject to FAA approval.

Since the AIP and the PFC program began, most funds used for noise-related
projects have been used to acquire land and to soundproof buildings. This
pattern generally holds true for both large and small airports.

Methods for measuring airport-related noise identify noise levels from a
single takeoff or landing or the average cumulative noise levels that
communities near airports are exposed to over time. Within these two
categories, different methods provide different kinds of information about
airport-related noise.

There are two principal methods for measuring the sound generated by a
single aircraft landing or takeoff: the (1) Maximum Sound Level, which
identifies the maximum sound level that the event produces and (2) Sound
Exposure Level, which identifies the cumulative sound that a person is
exposed to during the event if the sound were compressed into one second of
time.

There are three principal methods for measuring the average cumulative
exposure of nearby communities to airport-related noise. Those three methods
identify noise contours on a map of the area surrounding an airport, similar
to the lines on a map that illustrates land elevations. Each method produces
different noise contours for a given airport because each assigns different
weights to flights occurring during different times of day. One method,
known as the Equivalent Sound Level method, treats the impact of noise from
all flights equally regardless of the time of day. A second method, the
Day-Night Sound Level method, adds weight for flights occurring between 10
p.m. and 7 a.m. (nighttime flights). The third method, the Community Noise
Equivalent Level method, adds the same weight to nighttime flights as the
second method but also assigns added weight for flights occurring between 7
p.m. and 10 p.m. (evening flights). The added weight to evening and/or
nighttime flights is designed to reflect the higher degree of annoyance such
flights are believed to cause by interfering with sleep, conversation, or
similar activities. Figure 1 shows the differences in the measurements
produced by the three methods. These noise contours are based on an airport
model GAO developed.

Figure 1: Noise Contours at 65 and 60 Decibels for Three Measurement Methods
Note: These diagrams illustrate the comparative geographical size of the
noise contours produced by the aircraft that land at and take off from the
airport structure used in our model. As the mileage markers indicate,
aircraft are approaching the airport runway from the left of the diagram and
are taking off towards the right of the diagram. The vertical demarcation at
zero miles is the beginning of the airport runway. For a specific airport,
these contours would be delineated on a geographic map that illustrates the
airport and identifies the communities around the airport.

FAA chose the Day-Night Sound Level method for measuring the impact of
airport-related noise. Aviation experts generally agree that this method
best meets the statutory requirement that FAA establish a single system for
determining the exposure of people to airport-related noise.

Weight and Number of Engines

Pursuant to statutory directive, FAA establishes the noise standards--limits
on the noise that aircraft may generate--for civil subsonic turbojet
aircraft. Since the late 1960s, FAA has set increasingly stringent noise
standards for those aircraft. Noise standards are generally based on an
aircraft's weight and the number of engines. Different standards are
prescribed for takeoff, landing, and sideline emissions.3 Noise standards
were first applied to new aircraft designs, later to newly manufactured
aircraft, and finally, retroactively to some existing aircraft. As a result,
some aircraft are in operation that are not required to meet the most recent
noise limits.

The current standards, known as stage 3 standards, permit higher noise
levels for heavier aircraft because the noise generated by an aircraft is
generally determined by the thrust powering the aircraft--the heavier the
aircraft, the more thrust it needs. Also, aircraft with more engines are
generally permitted to have higher takeoff noise levels than aircraft
weighing the same but with fewer engines. According to a 1990 act, all civil
subsonic turbojet aircraft weighing more than 75,000 pounds had to be
retired from operations by December 31, 1999, if they did not meet stage 3
standards.

However, the statute did not impose this requirement on such existing
aircraft weighing 75,000 pounds or less. These aircraft also did not have to
be retired if they did not meet earlier noise standards, known as stage 2
standards, which FAA imposed in 1977, because FAA determined that the
cost-effectiveness of implementing the necessary modifications was
questionable.

As of October 1, 1999, there were just over 9,000 civil subsonic turbojets
weighing 75,000 pounds or less that FAA had certified as airworthy, and
about 31 percent of these are not required to meet stage 3 standards.

to Information

Land use planning is one way that communities can alleviate the impact of
airport-related noise. For example, communities may prohibit the
construction of schools within a certain distance from an airport so that
airport-related noise will not interrupt classes. While the federal
government has no decision-making role in land use planning, FAA reviews and
approves, as required by statute, airport noise compatibility programs and
identifies land uses that it considers compatible or incompatible with
various noise exposure levels. FAA has recently embarked on a Land Use
Planning Initiative, which is intended to encourage and assist state and
local governments to prevent future incompatible land uses near airports.

Under this Initiative, FAA requested--in a May 1998 Federal Register
notice--suggestions for promoting compatible land use planning by state and
local governments. After reviewing the submissions, FAA announced in May
1999 five short-term actions it would undertake: (1) develop an information
package on land use planning, (2) develop an information package on land use
statutes, (3) establish an information clearinghouse, (4) develop procedures
to rapidly respond to inquiries from local communities and airports, and (5)
clarify the actions it will consider when noise levels begin to rise in
certain areas. As of April 26, 2000, FAA had implemented the third and fifth
actions and expected the remaining actions to be implemented by May 2000.

In reviewing public comments on the initiative and discussing it with
aviation officials and other experts, GAO found that the initiative has
highlighted some key questions about how best to address airport-related
noise: (1) Should FAA's role in land use planning be more proactive or
should it focus its limited resources on activities over which it has direct
jurisdiction? (2) Should the noise exposure level defining compatible land
use be lowered or retained at 65 decibels using the Day-Night Sound Level
method? (3) Should the use of supplemental information, such as single event
noise measures, be required when measuring noise impacts for environmental
impact analyses of airport development projects? and
(4) How should federally authorized investment in the growth of airport
capacity be directed in view of the noise and physical expansion constraints
facing so many of the nation's airports?

GAO provided the Department of Transportation, the National Association of
State Aviation Officials, an advisory panel of five experts, the Airports
Council International-North America, the General Aviation Manufacturers
Association, and the Air Transport Association of America, Inc. with copies
of the draft report for their review and comment.

GAO met with officials from the Department of Transportation, including
FAA's Manager, Community and Environmental Needs Division, and spoke with
FAA's Manager, Noise Division. These officials generally agreed with the
facts in the report and provided clarifying comments, which were
incorporated as appropriate. The National Association of State Aviation
Officials and the advisory panel of experts generally agreed with the facts
in the report and provided technical and clarifying comments, which were
incorporated as appropriate. The Airports Council International-North
America provided no comments.

GAO spoke with the President of the General Aviation Manufacturers
Association, who stated that the report reflects a good effort to make a
difficult topic understandable, but was concerned that the draft report
(1) implied that aircraft not subject to phased compliance with operating
noise limits were not subject to any noise standards; (2) did not explain
that the exception of lighter aircraft from compliance with stage 3
operating noise limits was consistent with international operating rules;
and (3) overestimated how many aircraft weighing 75,000 pounds or less still
operate in the United States. The President further believed the general
aviation aircraft selected for the airport model were not representative of
the operating fleet.

With regard to the Association's first concern, while GAO believes the draft
report accurately explained the progressive application of noise standards
to aircraft, it revised the draft to clarify this point. Regarding the
second concern, this report focuses on FAA's role rather than on
international activities. Nevertheless, the draft report was revised to
clarify that the United States is a member of the International Civil
Aviation Organization and as such participates in that organization's
activities regarding aircraft noise standards. Concerning the final issue,
data in the draft report on the number of aircraft weighing 75,000 pounds or
less include all such aircraft certificated by FAA as airworthy. In
contrast, data provided by the Association include only the operating
business fleet, which is a subset of FAA's list of certificated aircraft.
With regard to the selection of aircraft for the model, GAO began with the
universe of certificated aircraft and selected two general aviation aircraft
from this list, as well as four others. The draft report was revised to
clarify that aircraft were selected from the list of certificated aircraft.

GAO met with officials from the Air Transport Association of America, Inc.,
who stated that the draft report was generally very good, but who expressed
concern that the draft report (1) did not fully recognize the significant
progress that the Congress, FAA, airports, and the airlines have made in
reducing the number of people exposed to noise from aircraft;
(2) did not fully reflect the role of international agreements and
obligations related to noise control; (3) was overly broad in its discussion
of flight procedures for abating noise; (4) included only two aircraft in
the airport model, one of which is no longer being produced, and did not
address current production aircraft; and (5) did not fully reflect the
potential trade-offs between noise stringency standards and aircraft
emissions.

With regard to the first concern, GAO agrees that the aviation industry and
the federal government have made substantial progress in reducing noise
generated by airports. However, forecast growth in aviation activity could
reduce or eliminate the benefits at individual airports. The draft report
was revised to clarify these points. With regard to the second issue, GAO
agrees that the international administrative and regulatory framework for
developing and implementing aircraft noise standards is important for the
aviation industry. However, this report focuses on FAA's role rather than on
international activities. Nevertheless, the draft report was revised to
clarify that the United States is a member of the International Civil
Aviation Organization and as such participates in that organization's
activities regarding aircraft noise standards. Regarding the third concern,
GAO's draft report provided FAA's rationale for not applying a retirement
deadline to stage 1 aircraft weighing 75,000 pounds or less. As noted in the
report, FAA did not consider flight operations to be an appropriate
operational noise abatement procedure for the purpose of meeting aircraft
noise standards. Accordingly, GAO did not revise this discussion in the
draft report. With regard to the fourth concern, the Association incorrectly
concluded that the airport model included only two aircraft. The model was
designed to provide a reasonable facsimile of an airport for use in
comparing and illustrating the various noise measurement methods. Six
aircraft were selected from FAA's list of certificated aircraft to represent
categories of aircraft operations. With regard to the final concern, the
draft report was revised to acknowledge that reducing aircraft noise may
result in higher aircraft emissions. A more detailed discussion of the
agencies' comments is presented at the end of chapter 5.

Introduction

Since the introduction of turbojet aircraft in the late 1950s for commercial
passenger service, airport-related noise has generated controversy with many
surrounding communities and emerged as a constraint on airport development.
Airport-related noise emanates primarily from the takeoff and landing of
aircraft, but engine maintenance and the taxiing of aircraft on runways are
some of the other activities that also contribute to airport-related noise.
New technology has been making aircraft quieter, and since 1969 the Federal
Aviation Administration (FAA) has been limiting the noise that various
aircraft are allowed to make. As a result, FAA estimates that the population
exposed to very high noise levels will have declined from
7 million in 1975 to an estimated 600,000 in 2000. But in spite of the
recent transition to quieter aircraft, expected growth in air traffic may
result in little or no net reduction in overall noise levels generated by
individual airports. Furthermore, concerns about airport-related noise may
impede the development of any needed additional capacity in the national
network of airports.

The Congress has recognized the importance of developing a safe and
efficient national airport system that meets the nation's present and future
aviation needs. As a result, federally authorized investment in a national
airport system, including noise reduction projects, has totaled about
$3 billion a year in recent years. FAA has primary responsibility for
implementing federal programs addressing noise issues associated with
civilian airports.4

In order to facilitate the development of a safe and efficient national
airport system, FAA undertakes several activities that help airports and
communities reduce airport-related noise or mitigate its effects. FAA must
consult with the Environmental Protection Agency regarding some of its
responsibilities. FAA's activities focus on three areas: (1) reducing
aircraft-generated noise at its source--the aircraft; (2) changing an
airport's use of its runways and/or implementing different flight
operations; and
(3) mitigating the effects of existing noise levels on surrounding
communities.

Airport-related noise can be lowered by reducing the noise that aircraft
emit when they take off from and land at airports. New technology allows
aircraft manufacturers to design and construct quieter aircraft. For
aircraft already in service, noise levels can be reduced by (1) installing
quieter engines, (2) installing equipment that reduces the noise of existing
engines, and (3) modifying aircraft use and operations in ways that reduce
aircraft-generated noise.

FAA has actively engaged in efforts to reduce aircraft noise since the
1960s. The agency sets the noise standards aircraft must meet to be
certified as airworthy and establishes the regulations that govern the
operation of those aircraft at U.S. airports.5 The Federal Aviation Act of
1958, as amended in 1968, gave FAA the authority to regulate aircraft design
and equipment in order to reduce noise. Pursuant to that act, FAA issued
regulations in 1969 that established noise standards for new designs of
civil subsonic turbojet aircraft. According to an aircraft design expert,
the purpose of those noise standards was to ensure that the best available
noise reduction technology was used in new aircraft designs.

Initially, these regulations prescribed noise standards that applied only to
new types or designs of turbojet aircraft (as well as certain propeller
aircraft). In 1973, FAA amended its regulations to apply the noise standards
to all newly manufactured aircraft, whether or not the aircraft design was
new. In 1977, additional amendments established lower noise standards for
all new aircraft, as well as the concept of noise "stages." Aircraft meeting
the original 1969 standards were categorized as "stage 2" aircraft; those
meeting the more stringent 1977 standards were categorized as "stage 3"
aircraft; and aircraft meeting neither standard were categorized as "stage
1" aircraft.

In addition to establishing noise standards, FAA controls aircraft noise by
regulating aircraft operations. In 1976, FAA amended its regulations to
prohibit all certificated stage 1 subsonic turbojet aircraft weighing more
than 75,000 pounds from flying into or out of U.S. airports after January 1,
1985, unless their engines had been modified or replaced to enable them to
meet the stage 2 or stage 3 noise standards. However, the Aviation Safety
and Noise Abatement Act of 1979 directed FAA to grant exemptions from
compliance until January 1, 1988, to turbojet aircraft with two engines and
fewer than 100 passenger seats.

In 1990, the Airport Noise and Capacity Act required civil subsonic turbojet
aircraft weighing more than 75,000 pounds to comply with stage 3 noise
standards by December 31, 1999, or be retired from service. To meet this
requirement, the engines on stage 2 aircraft could be modified or replaced.

In addition to regulating aircraft-generated noise, FAA supports aviation
research related to noise. In particular, FAA is working with the National
Aeronautics and Space Administration to develop new technology to reduce
aircraft noise.

By changing use and/or operations, airports can reduce airport-related noise
or mitigate its effects. For example, an airport can restrict noisy aircraft
maintenance activities to areas where noise barriers can muffle the sound.
Aircraft arrival and departure flight paths, as well as runway use, can be
changed to minimize flights over densely populated areas. Airports can also
mitigate noise impacts by seeking FAA approval to restrict certain aircraft
to takeoffs and landings during the day, when their impact on nearby
communities is considered less than during the night.6

FAA is involved in many of these activities. For example, FAA must approve
any restriction on an aircraft's access to an airport or on allowable noise
levels if the restriction involves stage 3 aircraft or is beyond those
imposed by federal regulations. Thus, if an airport wants to restrict any
stage 3 aircraft to daytime operations, it must obtain FAA's approval. FAA
must also approve and implement changes in flight paths. Furthermore, FAA
administers airport development funding programs, which can finance the
construction of runways and taxiways that enable aircraft to use different
takeoff and landing routes to minimize flights traveling over densely
populated areas.

Mitigation activities can reduce the impact of airport-related noise on the
communities surrounding an airport. For example, buildings in nearby
communities can be soundproofed and building codes can be changed to require
improved sound suppression construction; noise barriers can be constructed;
and airports can acquire land to prevent uses that are incompatible with the
prevailing noise exposure levels.7 Communities can also exercise their
authority over land use planning to help prevent the future development of
land for activities that are noise-sensitive--such as those occurring in
residences, schools, churches, and hospitals--in areas exposed to high noise
levels.

FAA supports mitigation efforts through two programs that provide federally
authorized funds for airport projects that mitigate the effects of noise,
and one program that encourages airports to identify and address the noise
impacts of their airports on nearby communities.

FAA Administers Two Programs That Fund Noise Mitigation Projects

The Airport Improvement Program (AIP) and the Passenger Facility Charge
(PFC) program provide federally authorized funding that, among other
purposes, can be used to help mitigate the effects of airport-related noise.
The AIP, established by the Airport and Airway Improvement Act of 1982,
provides federal grants--funded by congressional appropriations from the
Airport and Airway Trust Fund8--for developing airport infrastructure,
including projects that reduce airport-related noise or mitigate its
effects. Airports must provide a "matching share" for AIP-funded projects,
ranging from 10 percent to 25 percent of a project's total cost, depending
on the type of project and the size of the airport.9

Two categories of AIP grants are available--apportionment and discretionary.
Apportionment funds are distributed by a statutory formula to commercial
service airports according to the number of passengers served and the volume
of cargo moved, and to the states according to a percentage of the total
amount of the appropriated funds. Discretionary funds--for the most part,
those amounts remaining after apportionment funds are allotted and certain
other amounts are "set aside" for special categories, including
noise-related projects--can generally be awarded for eligible projects at
any eligible airport, including general aviation airports, which do not
receive apportionment funds.

Only airports included in FAA's National Plan of Integrated Airport Systems
are eligible for AIP grants. The National Plan of Integrated Airport Systems
identifies those U.S. airports that constitute the national airport system,
which is designed to ensure that every part of the country has an effective
aviation infrastructure. There are 529 commercial service airports--those
that receive apportionment funds--and 2,815 general aviation airports (for a
total of 3,344 airports) in the current national plan. Furthermore, all
projects funded with AIP funds--whether apportionment or discretionary--must
be approved by FAA. However, FAA will not approve any grant for any kind of
project without written assurances that the airport will take appropriate
action, to the extent possible, to restrict the use of land near the airport
to uses compatible with airport operations.

The AIP funds noise mitigation projects in two ways. First, a specified
portion of AIP appropriations is "set aside" by statute specifically for
projects that address airport-related noise levels and their effects. Only
projects relating to noise may be funded from this set-aside. Table 1
identifies the portions of AIP funds that have historically been set aside
for noise. In addition to being eligible for these set-aside funds, projects
addressing airport-related noise may compete with other airport development
projects for other AIP grants.

Table 1: Portions of AIP Funds Set Aside for Noise Mitigation Projects,
Fiscal Years 1982 Through 1999

 Fiscal year       Amount set aside for noise-related projects
 1982 through 1986 8 percent of total AIP
 1987 through 1991 10 percent of total AIP
 1992 through 1995 12.5 percent of total AIP
 1996 through 1999 31 percent of AIP discretionary funds
 2000              34 percent of AIP discretionary funds

Source: P.L. 97-248, section 508(d); P.L. 100-223, section 107(a); P.L.
102-581, section 108; and P.L. 104-264, section 123; P.L. 106-181, section
104(e).

The second program providing federally authorized funds for mitigating
airport-related noise--the PFC program10--is a voluntary program that
enables airports to impose fees on boarding passengers--known as passenger
facility charges--and retain the money for airport infrastructure projects,
including noise reduction. Under this program, authorized by the Aviation
Safety and Capacity Expansion Act of 1990, commercial service airports may
charge boarding passengers a $1, $2, or $3 fee.11 Airports are not required
to impose the fee, but airports wishing to participate in the program must
seek FAA's approval both to levy the fee and to use the revenues for
particular development projects. Airlines collect the fees from passengers
and transmit them directly to the appropriate airports.12 FAA officials told
us that as long as a project is eligible, meets one of the statutory
objectives, and is adequately justified, they do not have the authority to
reject an airport's proposal for the collection or use of passenger facility
charges.

FAA Defines Land Use Compatibility and Administers an Airport Noise
Compatibility Planning Program to Facilitate Noise Mitigation

Although the federal government has no jurisdiction over land use decisions
(that authority lies with state and local governments), FAA can facilitate
compatible land use planning at the state and local level. The Aviation
Safety and Noise Abatement Act of 1979 directed FAA to define land uses that
it considers compatible or incompatible with the various noise levels that
nearby communities are exposed to. The act also directed FAA to administer a
new program that encourages airports to develop maps identifying areas in
nearby communities where land uses are considered to be incompatible. The
program also encourages airports to develop individual airport noise
compatibility programs that include those maps and the projects that have
been implemented, or planned, to reduce any existing or potential
incompatible land uses identified. The act also requires FAA to approve an
airport's noise compatibility program13 as long as the program

ï¿½ does not place an unreasonable burden on interstate or foreign commerce,

ï¿½ is reasonably consistent with achieving the goal of reducing incompatible
land uses and preventing the introduction of new incompatible land uses, and

ï¿½ authorizes needed revisions to the program's planned projects when noise
exposure maps are updated.

Programs, except as they relate to flight procedures, are automatically
approved if FAA has not acted within 180 days after receipt of the proposed
program. Once an airport's program is approved, the airport can apply for
AIP grants to fund the types of projects included in the program that are
eligible for federal grants. Through fiscal year 1999, 195 airports had
FAA-approved noise compatibility programs, while 212 had approved noise
exposure maps.14 Appendix I describes the process for obtaining FAA approval
of the maps and airports' noise compatibility programs.

The Subcommittee on Aviation, House Committee on Transportation and
Infrastructure, and several Members of the House of Representatives asked us
to address four sets of questions about federal programs for airport
development and the alleviation of airport-related noise:

ï¿½ What kinds of projects that reduce airport-related noise or mitigate its
effects are eligible for federally authorized funding, how do FAA's
selection criteria affect which projects are funded, and to what types of
projects have the funds been historically distributed?

ï¿½ How do major methods for measuring the impact of airport-related noise
compare with each other, and what method has FAA selected?

ï¿½ What aircraft noise standards apply to civil subsonic turbojets, and why
are some civil subsonic jets not required to comply with these and earlier
noise standards?

ï¿½ What actions has FAA announced under its Land Use Planning Initiative,
what is the status of their implementation, and what issues has the
Initiative raised?

To address the first set of questions--on the eligibility of noise-related
projects for federally authorized funding--we (1) reviewed the statutory
provisions and FAA's regulations, policies, and procedures for funding
projects under the AIP and the PFC program to identify project eligibility;
(2) reviewed the statutory requirements for airport-related noise
compatibility programs, as well as FAA's regulations and processes for
implementing those requirements; (3) obtained FAA's data on federal grants
awarded for noise-related projects and passenger facility charges approved
for noise-related projects to identify the types of projects and the total
project funding by fiscal year for each type of noise-related project. We
also interviewed officials from FAA headquarters in Washington, D.C.; the
Airports Council International-North America; the Air Transport Association;
and the National Association of State Aviation Officials; as well as other
experts on these issues. In 1999, we independently validated the PFC project
database and found it to be very reliable (a 0.3-percent error rate). We did
not independently review the validity of the grant program database, but it
is the only database for that information, and we have used data from it
extensively during the conduct of several reviews that have looked at
various aspects of the grant program.

To address the second set of questions--on comparing methods that measure
airport-related noise--we (1) discussed noise measurement methods with FAA,
airport officials, the Airports Council International-North America, the Air
Transport Association, the National Association of State Aviation Officials,
and the Federal Interagency Committee on Noise, as well as other aviation
experts, to identify the kinds of methods being used to measure noise levels
and the strengths and weaknesses of these methods; (2) reviewed the major
noise measurement methods, as well as written descriptions and analyses of
them, to determine how each method measured airport-related noise; and (3)
identified the statutory requirements for FAA to select a method for
environmental impact and land use analyses and the method that FAA chose. To
compare and illustrate the kinds of information produced by each method, we
designed a model airport and test scenarios; FAA then conducted noise
measurements for us for the test scenarios using its Integrated Noise Model,
its computerized program for applying noise measurement methods. The methods
that were compared are the Maximum Sound Level and the Sound Exposure Levels
methods used to measure the noise of a single event, and the Equivalent
Sound Level, the Day-Night Sound Level, the Community Noise Equivalent
Level, and the Time-Above methods used to measure the levels of noise that
nearby communities are exposed to. We discussed the reliability of the
Integrated Noise Model with FAA officials and found that they had used
appropriate methods--including an independent assessment--to ensure the
model's reliability for measuring noise experienced at certain distances
from the source.

To address the third set of questions--on aircraft noise standards--we
reviewed the statutes, policies, and regulations governing noise levels for
civil subsonic jets, and we discussed these statutes, policies, and
regulations with FAA officials, representatives of the General Aviation
Manufacturers Association, the National Business Aviation Association, and
the Regional Aviation Association, and other experts. Through interviews and
document review, we identified activities under way in the United States,
Europe, and the International Civil Aviation Organization to address the
issue of a new level of more stringent aircraft noise standards--commonly
referred to as "stage 4" noise standards. To determine the number of
aircraft weighing less than 75,000 pounds that were not required to meet
FAA's most recent aircraft noise standards, we determined, from FAA's list
of aircraft in the United States that it has certified as airworthy, the
number of civil subsonic jets weighing
75,000 pounds or less. To identify the noise standard that those aircraft
met, we reviewed FAA documentation identifying noise stages for certain
aircraft, Jane's All The World's Aircraft, and aircraft manufacturers'
specifications for aircraft types. While we did not test the validity of
FAA's aircraft database, it is the only source for the information we
sought.

Finally, to address the fourth set of questions--on FAA's Land Use Planning
Initiative--we identified the overall objective of the Initiative, the
initial short-term actions that FAA announced in May 1999, and the status of
FAA's implementation of those actions. To determine if any issues were
raised by the Initiative, we reviewed and analyzed the public comments
submitted in response to FAA's request for comments and suggestions on its
land use planning effort under the Initiative, as well as published comments
analyzing the Initiative. We also interviewed officials at FAA, the Airports
Council International-North America, the National Association of State
Aviation Officials, and airport and community officials for Dulles
International Airport (a large hub without a completed noise compatibility
program) and Manassas Regional Airport (a general aviation airport with an
approved noise compatibility program), both in Virginia, and other aviation
experts to obtain their views.

A panel of five experts reviewed the design and methodology for our work.
These experts were selected because of their knowledge about aviation and
airport-related noise issues and FAA's noise programs. A list of the panel
members appears in appendix IX.

We conducted our review from July 1999 through April 2000 in accordance with
generally accepted government auditing standards.

Project Eligibility for Federally Authorized Funding Is Broad, but Other
Factors Affect Project Selection

Most types of projects to reduce airport-related noise or mitigate its
effects on nearby communities are eligible for federally authorized funding
through the Airport Improvement Program (AIP) and the Passenger Facility
Charge (PFC) program. Under the AIP, however, statutes require that, with a
few exceptions, projects be part of an airport's noise compatibility
program. Once an airport applies for AIP funding, FAA sets priorities for
projects using two types of project selection criteria before awarding the
grants. The PFC program is a more flexible funding source than the AIP, in
part because projects do not have to be part of an approved noise
compatibility program and because airports set their own priorities, subject
to FAA approval. Since the programs began, the majority of funds have been
used to acquire land and soundproof buildings.

Be Part of an FAA-Approved Airport Noise Compatibility Program

The types of noise-related projects eligible for AIP funding include such
efforts as developing information to prepare planning and noise
compatibility program documents, acquiring land, acquiring air rights or
other easements, purchasing noise-monitoring equipment, constructing noise
barriers, and soundproofing buildings. The construction or expansion of
runways and taxiways, which can reduce noise levels affecting some
communities by enabling flights to avoid densely populated areas, is also
eligible for AIP funding.

There are some statutory restrictions on eligibility. AIP grants may not be
approved for land purchases unless the airport provides written assurance
that the following conditions will be met:

ï¿½ the land will be sold at fair market value as soon as possible once it is
no longer needed to help mitigate the effects of noise;

ï¿½ an airport will retain a legal interest in the land when it is sold in
order to ensure that its use remains compatible; and

ï¿½ the government's share of the cost of purchasing the land will be
reimbursed when the land is sold.15

In addition, federal appropriations law prohibits the use of AIP funds for
studies, maps, or environmental impact analyses needed to implement flight
procedure changes made to reduce noise. These costs are paid for by other
appropriated funds for air traffic control.

In addition to these statutory restrictions, FAA policy prohibits using AIP
funds for remedial noise mitigation--such as soundproofing buildings--for
buildings that were known to be incompatible with prevailing noise exposure
levels before they were built.

To qualify for AIP funds that are set aside for noise-related projects, an
airport must have an FAA-approved noise compatibility program that includes
the projects the airport wants funded, except that projects to insulate
public buildings used primarily for educational or medical purposes can be
funded even though an airport does not have such a program. Nevertheless,
FAA approval of an airport's program does not guarantee that the projects in
it will receive AIP noise set-aside funding because an airport must apply
for AIP funding separately once its program is approved.

In addition, AIP funds may pay for projects that mitigate the noise impact
of other airport development projects--such as the construction of a new
runway--even if the noise-related projects are not included in an approved
noise compatibility program. The airport, however, would have to use its AIP
apportionment funds for those projects or the projects would have to compete
with other airport development projects for AIP discretionary funds.

Funding

In deciding which eligible projects to fund, FAA sets priorities using (1)
its guidance on land use compatibility and (2) a national priority system
that comparatively ranks all projects eligible for AIP funding. When
awarding AIP funds for projects included in an airport's noise compatibility
program, FAA gives priority to projects located in areas where noise
exposure levels are 65 decibels or higher (when measured under a method that
assigns greater weight to flights occurring between 10 p.m. and 7 a.m.).16
Projects are eligible for funding in areas with lower noise exposure levels.
However, according to FAA officials, nearly all of the AIP funds set aside
for noise-related projects in the past have been awarded for projects where
incompatible land uses occur in areas exposed to noise levels of
65 decibels or higher under FAA's chosen method for measuring community
exposure to airport-related noise.

FAA also sets priorities for AIP-eligible projects through a national
priority system that comparatively ranks all projects, including
noise-related projects, in order to identify those projects that most
warrant funding. First, FAA applies a formula that assigns projects a
numerical score from
0 to 100--the higher the score, the higher the priority. The formula ranks
projects by assigning points for each of four factors:

ï¿½ the project's purpose (for example, safety, security, capacity, planning,
reconstruction), with, safety and security projects, for example, receiving
more points--higher priority--than projects to develop airport capacity;

ï¿½ the size of the airport (for example, large, medium, or small commercial
service airports), with projects at larger airports receiving more points
than projects at smaller airports;

ï¿½ the project's component (for example, apron, equipment, building,
financing), with runway projects, for example, receiving more points than
projects for equipment or taxiways; and

ï¿½ the project type (for example, noise, by noise exposure level; airport
access; construction; de-icing facility; aircraft rescue; or fire-fighting
vehicle), with noise-related projects in areas exposed to high noise levels,
for example, receiving more points than noise-related projects in areas with
lower noise exposure levels.

FAA officials then consider other factors--such as benefit-cost analysis,
risk assessment, environmental issues, regional priorities, state and
metropolitan system plans, airport growth, and market forces--in determining
the final ranking of a project. FAA officials have discretion over the
relative importance of the formula and other factors in deciding the final
ranking of projects.

According to an FAA official, projects competing for AIP funds set aside for
noise-related projects are ranked on the basis of project type and airport
size because the values of the other two factors in the formula are the same
for all noise-related projects. As a result, projects in areas with higher
noise exposure levels and for larger airports will score higher under the
formula than projects in areas with lower noise exposure levels and for
smaller airports. When noise-related projects compete for other AIP
discretionary funds, however, all four factors in the formula contribute to
determining the project's comparative ranking.17

Even if an airport's project ranks relatively high, however, it may not be
funded in a given year. According to an FAA official, for the past few years
FAA has applied an administrative cap that limits the amount of AIP funding
awarded to any single airport in one year for noise-related projects. The
limit is $5 million for projects included in an airport's noise
compatibility program and $3 million for insulating public buildings used
primarily for educational or medical purposes (whether or not the airport
participates in the noise compatibility program). According to the FAA
official, FAA imposes the limits when the demand for AIP funds set aside
specifically for noise-related projects exceeds the amount of AIP funds
available. The limits are intended to ensure that all airports that need
funding for noise-related projects have access to AIP funds. The FAA
official explained that the agency has exceeded the limit for an airport
when sufficient funds were available to meet all demand and the airport was
able to document its ability to spend more in that year. The official also
said that each year FAA reevaluates whether the limits are needed; if the
total cost of the noise projects submitted for funding substantially exceed
the money available, the limits will generally remain in effect.

Grants

The statutes define eligible types of noise-related projects under the PFC
program as anything eligible for AIP funding. Unlike most projects funded
with AIP grants set aside for noise-related projects, however, PFC projects
do not have to be part of an FAA-approved noise compatibility program.
Nevertheless, according to FAA officials, FAA requires airports to
demonstrate that the projects will provide noise reduction or mitigation and
would qualify for inclusion in a noise compatibility program. In addition,
unlike AIP funds, PFC funds may be used to pay the financing costs for an
approved project and the nonfederal share of projects funded with AIP
grants. Airports can set their own priorities, subject to FAA approval,
regarding which noise-related projects to fund through the PFC program.

AIP and PFC Noise-Related Funding

More than 75 percent of all AIP funds and over 50 percent of all PFC funds
spent on noise reduction or mitigation have been used to acquire land and to
soundproof buildings.18 This is generally true for both large and small
airports. In this report, "large" airports are those airports categorized in
FAA's National Plan for Integrated Airport Systems--those airports eligible
for AIP grants--as large and medium hub airports. "Small" airports are those
categorized as small hub, nonhub, other commercial service, and general
aviation airports.

Of the nearly $24 billion in AIP grants awarded for fiscal years 198219
through 1999, over $2.7 billion, or 11.5 percent, were for noise-related
projects. Of this amount, $1.4 billion (over 50 percent) was used to acquire
land for noise mitigation purposes, and $673 million (nearly 25 percent) was
used to soundproof buildings. Figure 2 shows the distribution of total AIP
funds for noise-related projects by project type for fiscal years 1982
through 1999. Appendix III provides AIP funding data for noise-related
projects for each fiscal year, from 1982 through 1999, by project type.

Figure 2: AIP Noise-Related Projects, Fiscal Years 1982 Through 1999
(Total: $2.7 billion)
Note: Percentages do not total 100 percent because of rounding. Projects in
the category of miscellaneous include such things as acquiring and
installing noise monitoring equipment.

About $2.1 billion of the $2.7 billion in AIP noise-related grants went to
large airports and about $582 million went to small airports for
noise-related projects. As figure 3 shows, both large and small airports
targeted their AIP grants for land acquisition and soundproofing buildings.

Figure 3: AIP Noise-Related Projects, Fiscal Years 1982 Through 1999 for
Large Airports (Total: $2.1 billion) and for Small Airports (Total: $582
million)
Note: State block grants of $18 million (0.7 percent of total AIP) are not
included in this figure because data do not show the use of these funds by
large versus small airports.

For fiscal years 199220 through 1999, FAA approved the collection of nearly
$24 billion in passenger facility charges, with over $1.6 billion, or
6.9 percent, approved for noise-related projects.21 About $755 million
(46 percent) of this funding has been approved for projects that will
require multiple phases to complete. These projects consist of one or more
different types of projects that are approved together--usually combinations
of soundproofing and land acquisition, according to an FAA official. About
$481 million (just over 29 percent) has been approved for projects to
soundproof buildings, while $378 million (23 percent) has been approved for
projects to acquire land. Figure 4 shows the distribution of noise-related
projects approved for fiscal years 1992 through 1999, by project type.
Appendix IV provides data on the amount of PFC funds approved in each fiscal
year, from 1992 through 1999, by project type.

Figure 4: PFC Noise-Related Projects, Fiscal Years 1992 Through 1999
(Total: $1.6 billion)
Note: PFC funds used to pay interest costs for project financing are
categorized as "interest" projects, and not on the basis of the type of
projects being financed. Any interest projects related to noise, therefore,
are not reflected in these data. According to an FAA official, very few, if
any, interest projects are related to noise.

Of the $1.6 billion in PFC funds approved for noise-related projects, nearly
all was approved for large airports, while about $46 million was approved
for small airports. FAA has approved about the same portion of
multiple-phase projects for large and small airports at 46 percent ($735
million) and 45 percent ($21 million) respectively. However, large and small
airports differ in their use of PFC funds for other types of projects. For
example, large airports had a much larger portion of their funds approved
for soundproofing buildings. Figure 5 illustrates the funding pattern by
project type for large and small airports.

Figure 5: PFC Noise-Related Projects, Fiscal Years 1992 Through 1999 for
Large Airports (Total: $1.59 billion) and for Small Airports (Total: $45.6
million)
Note: PFC funds used to pay interest costs for project financing are
categorized as "interest" projects, and not on the basis of the type of
projects being financed. Any interest projects related to noise, therefore,
are not reflected in these data. According to an FAA official, very few, if
any, interest projects are related to noise.

aPercentages do not total 100 percent because of rounding.

Noise Measurement Methods Provide Different Kinds of Information

Methods for measuring airport-related noise assess noise either from a
single takeoff or landing or from the cumulative average noise that nearby
communities are exposed to over time. Required by law to select a single
method for measuring the impact of airport-related noise on communities, FAA
chose a method that measures community exposure levels and that gives
greater weight to the impact of flights occurring during the nighttime.
While subsequent studies have confirmed that this method best meets the
statutory requirement that FAA establish a single system for determining the
exposure of people to airport-related noise, a federal interagency committee
addressing airport-related noise issues found that supplemental information,
such as measures of noise from a single aircraft takeoff or landing, is also
useful in explaining the noise that people are likely to hear. In addition,
experts and community groups believe FAA's chosen method provides
insufficient information because it does not effectively convey to people
what they can actually expect to hear in any given area.

To understand the methods used to measure noise, it is necessary to have
some understanding of how sound is measured and how it affects humans. Some
basic concepts include (1) sound waves and their measurement in decibels,
(2) human ability to hear the entire range of sounds made, and
(3) noise as a source of interference in people's activities.

First, sound radiates in "waves" from its source and decreases in loudness
the further the listener is from the source.22 As sound radiates from its
source, it forms a sphere of sound energy. Sound waves exert sound pressure,
commonly called a "sound level" or "noise level," that is measured in
decibels.23 The higher the number of decibels, the louder the sound appears
to someone hearing it. But because decibel levels are measured
logarithmically, an increase of only 10 decibels--for example, from 50
decibels to 60 decibels--doubles the loudness that people believe they
hear.24 Continuing the increase from 60 to 70 decibels would again double
the perceived loudness of the sound. Which sounds are considered to be
noise, however, is subjective.

In terms of aircraft noise, sound levels generated by takeoffs or landings
vary depending on several factors, particularly the aircraft's weight and
the number of engines. While airport-related noise levels decrease quickly
with distance from an airport, the accuracy of noise measurement also
decreases because it is more difficult to distinguish between
airport-related noise and other noise in the environment.

Second, while the human ear can hear a broad range of sounds, it cannot hear
all sounds. Sounds with very low pitches (low frequencies) and sounds with
extremely high pitches (high frequencies) are generally outside the hearing
range of humans. Because of this, environmental noise is usually measured in
"A-weighted" decibels. The A-weighted decibel unit focuses on those sounds
the human ear hears most clearly and deemphasizes those sounds that humans
generally do not hear as clearly. Table 2 illustrates the typical sound
levels of some common events.

Table 2: Typical Sound Levels of Common Occurrences

 Event                                Sound level in
                                      A-weighted decibels
 Rock band (indoors)                  108-114
 Food blender                         88
 Vacuum cleaner                       70
 Conversation (indoors)               60
 Dishwasher on rinse cycle at 10 feet 60
 Bird calls (outdoors)                44

Source: Federal Interagency Review of Selected Airport Noise Analysis Issues
(Federal Interagency Committee on Noise; August 1992).

Finally, the impact of noise on communities is usually analyzed or described
in terms of the extent to which it annoys people. Annoyance refers to the
degree to which noise interferes with activities such as sleep, relaxation,
speech, television, school, and business operations. While it is difficult
to predict how an individual might respond to, or be affected by, various
sounds or noises, some studies indicate that it is possible to estimate what
proportion of a population group will be "highly annoyed" by various sound
levels created by transportation activities. The findings of a 1978 study
that related transportation noise exposure to annoyance in communities has
become the generally accepted model for assessing the effects of long-term
noise exposure on communities.25 According to this study, when sound
exposure levels are measured by a method that assigns additional weight to
sounds occurring between 10 p.m. and 7 a.m., and those sound levels exceed
65 decibels, individuals report a noticeable increase in annoyance.

Operations and Community Exposure

Methods for measuring airport-related noise provide different kinds of
information. First, airport-related noise can be measured from single
events--such as an individual aircraft's takeoff or landing--or as the
cumulative average level of noise that communities near airports are exposed
to over time. Principal methods for measuring cumulative average noise
levels identify geographic areas exposed to the same noise levels but apply
different weights to flights occurring during different times of the day.

The noise from a single takeoff or landing usually starts when the sound can
be heard above the background noise; it reaches a maximum sound level and
then recedes until the sound is hidden below the background noise level. One
of two measures of the noise from a single takeoff or landing is commonly
used: (1) the Maximum Sound Level method, which identifies the maximum sound
level produced by the event, and (2) the Sound Exposure Level method, which
measures the total sound energy that a listener is exposed to during a
single event.

The Maximum Sound Level method is usually expressed in A-weighted decibels
when measuring aircraft events. It does not provide any information,
however, about the duration of the event or the amount of sound energy
produced.

In contrast, the Sound Exposure Level method measures all of the sound
energy from the duration of a takeoff or landing to produce the sound level
that a person is exposed to from that event. Thus, this method reflects both
the intensity and the duration of the sound that the takeoff or landing
produces. For aircraft events, this method also usually uses A-weighted
decibels. Because this method measures the cumulative sound energy averaged
over a single second of time, the sound exposure level for an event that
lasts longer than one second will be higher than the maximum sound level for
that same event. Also, two events can have the same maximum sound level but
different sound exposure levels. The event that lasts the longest will have
a higher decibel measure than the shorter event, even though both may have
the same maximum sound level.

To compare the different kinds of information these methods provide, FAA
calculated maximum sound levels and sound exposure levels for single
aircraft takeoffs and landings using an airport model that we designed.26
The results illustrate the different concepts embodied in the two measures
of single events. Figure 6 illustrates the measures produced by both methods
at one-half mile from the runway and at 1-mile intervals from the runway,
for both approach and takeoff operations, for the Boeing 747 and C140
aircraft included in our model. Similar figures for the four other aircraft
in our model appear in appendix VI.27

Figure 6: Single Event Noise Levels Using the Maximum Sound Level Method and
the Sound Exposure Level Method, Approach and Takeoff--Boeing 747 and C140
Aircraft
Measuring the noise from a single takeoff or landing does not reflect or
measure the impact of the noise from several takeoffs or landings in
comparison with the impact of just one aircraft operation. According to FAA
officials, although some research correlates the health and welfare effects
of noise generated by certain kinds of single events, the Federal
Interagency Committee on Noise pointed out in 1992 that there is no accepted
methodology for aggregating the information on the noise levels of single
events in a way that would explain the cumulative impact of those events on
people in the communities surrounding airports.28 Thus, by themselves,
methods to measure the noise from single events are not considered to
describe the overall noise environment.

The level of noise from airports that nearby communities are exposed to
depends on several factors, including the types of aircraft using the
airport, the overall number of takeoffs and landings, the time of day those
aircraft operations occur, the runways that are used, weather conditions,
and airport-specific flight procedures that affect the noise produced by a
takeoff or landing. There are two approaches to measuring community exposure
to noise: (1) identifying geographic areas on a map that are exposed to the
same noise levels or (2) determining the length of time that a specific
geographic area is exposed to particular noise levels.

Key Measurement Methods Use Contour Maps to Identify Geographic Areas
Exposed to Noise Levels

The three main methods for measuring airport-related noise levels that
nearby communities are exposed to include (1) the Equivalent Sound Level
method; (2) the Day-Night Sound Level method; and (3) the Community Noise
Equivalent Level method. These methods provide long-term, or cumulative,
measures of exposure to noise. For each method, the key factors that
determine the noise exposure level affecting a community are the types of
aircraft using the airport, the number and type of engines on an aircraft,
the number of takeoffs and landings that occur during an average day,29 and
the time of day during which those aircraft operations occur. The measures
are generally presented in the form of "noise contours" on maps--lines
around an airport that connect all the areas exposed to the same average
sound level. A series of contours are drawn, usually at
5-decibel decrements from the airport, to produce a map that looks similar
to a land elevation map. All three methods incorporate both the intensity of
sounds produced by single events and the average frequency of those events.

The first method--the Equivalent Sound Level--measures the average noise
level over a specified time using A-weighted decibels. Because the method is
based on a logarithmic average, it gives greater weight to higher noise
levels than to lower ones. For example, if sound is measured at
50 decibels for a half hour and 100 decibels for a half hour, the Equivalent
Sound Level measure for the entire hour is 97 decibels, not the 75 that
would result from simple averaging. Any time period can be used, with
typical time periods being 1 hour, or 1 day (24 hours). Under this method,
all flights are weighted equally regardless of when they occur during the
day.

The second method--the Day-Night Sound Level--is the same as the Equivalent
Sound Level method for a 24-hour period, but it gives greater weight to
flights occurring during the nighttime--between 10 p.m. and
7 a.m. Additional weight is given to nighttime flights because they are more
likely to interrupt sleep, relaxation, or other activities and because the
background noise level during those hours is lower. To reflect that greater
impact, the Day-Night Sound Level method equates 1 nighttime aircraft
operation to 10 equivalent daytime operations. This effectively adds
10 decibels to the noise produced by each takeoff or landing that occurs
during those nighttime hours. That is, the noise impact of each single
nighttime takeoff or landing is reflected in the noise exposure level as if
it were 10 daytime takeoffs or landings. For example, if eight takeoffs and
eight landings occur between 7 a.m. and 10 p.m., they are reflected in the
noise exposure level as 16 aircraft operations. If those same eight takeoffs
and eight landings all occur between 10 p.m. and 7 a.m., they are reflected
in the noise exposure levels as the equivalent of 160 aircraft operations.

Finally, the Community Noise Equivalent Level modifies the Day-Night Sound
Level method by adding additional weight to flights occurring between the
evening hours of 7 p.m. and 10 p.m. to account for an assumption that
greater interference with activities may be occurring during the early
evening than during the daytime.30 The second and third methods are
considered to have only small differences.

Under each of the three methods, several different combinations of flights
can produce the same noise exposure level because factors such as the total
number of flights and the type of aircraft affect the noise exposure levels.
For example, each of the following three scenarios will produce the same 65
decibel noise exposure level under the Day-Night Sound Level method:

ï¿½ 500 aircraft operations with an average sound exposure level of
87.4 decibels;

ï¿½ 100 aircraft operations with an average sound exposure level of
94.4 decibels; and

ï¿½ 50 aircraft operations with an average sound exposure level of
97.4 decibels.

Because different combinations of flights can produce the same noise
exposure level, and because these methods use additional weighting for
evening and/or nighttime flights, FAA does not consider these methods to be
good estimators of the noise level produced by a single event.31

We compared the noise contours produced by these three methods at various
decibel levels using our airport model. As figure 7 illustrates, the
Equivalent Sound Level method, which does not add weighting to evening or
nighttime flights, produced not only the smallest areas exposed to various
noise levels but also markedly smaller areas than the other two methods,
which include the effects of additional weighting. The noise contours
produced by the Day-Night Sound Level method identified areas that ranged
from about 2- times as large to 3- times as large as the areas exposed to
the same noise levels under the Equivalent Sound Level method. On the other
hand, the size of the areas exposed to the same noise levels were almost
identical under the Day-Night Sound Level method and the Community Noise
Equivalent Level method. The latter produced a
5 percent or less increase in the size of those areas.32

Figure 7: Noise Contours for Sound Equivalent Level, Day-Night Sound Level,
and Community Noise Equivalent Level Measurement Methods, at 75, 70, 65, 60,
and 55 A-weighted Decibels
Note: These diagrams illustrate the comparative geographical size of the
noise contours produced by the aircraft that land at, and takeoff from, the
airport used in our model. As the mileage markers indicate, aircraft are
approaching the airport runway from the left of the diagram and are taking
off towards the right of the diagram. The vertical demarcation at zero miles
is the beginning of the airport runway. For a specific airport, these
contours would be delineated on a geographic map that illustrates the
airport and identifies the communities around the airport.

At our request, FAA also used our airport model to examine the results from
the different measurement methods when (1) flights were shifted by time of
day and (2) more aircraft operations were added.

In the first scenario, our model illustrated the effect of assigning
additional weight to flights occurring during different times of the day. In
this scenario, FAA calculated the noise exposure levels for seven different
flight schedules.33 All three methods produced the exact same contours when
all flights occurred during the day because no method applies additional
weighting to daytime flights. However, when all flights occurred during the
nighttime, both the Day-Night Sound Level and the Community Noise Equivalent
Level produced contours that quadrupled the size of the areas exposed to the
different noise levels.34 Table 3 illustrates the impact of changing flight
schedules.

Table 3: Effects of Scheduling Changes on Noise Exposure Levels Using Three
Measurement Methods

                    Flight Schedule

 Method             All daytime    All evening        All nighttime flights
                    flights        flights
 Equivalent Sound   Areas exposed
 Level              to noisea      No change          No change
 Day-Night Sound    Areas exposed                     More than quadrupled
 Level              to noisea      No change          size of areas

 Community Noise    Areas exposed  Doubled size of    More than quadrupled
 Equivalent         to noisea      areas exposed to   size of areas
                                   noise

aWhen all flights occurred during the day, all three methods produced the
exact same size areas exposed to the various noise levels.

In the second scenario, to understand how the number of aircraft operations
at an airport can affect the noise contours, we looked at the results under
each of the three methods, for seven cases in which the total number of
takeoffs and landings were increased at various increments.35 The results
showed that increasing the number of operations produced a consistent
increase in the size of the exposure area at each noise level under each
method. That is, the greater the number of operations, the further out each
exposure level contour extended from the airport under each method.
Consistent with the results illustrated in figure 7, the total area affected
by the Equivalent Sound Level method under each scenario was noticeably
smaller than that of the other two methods. Also, the size of the areas
exposed to each noise level under the Community Noise Equivalent Level
method, for each level of operations tested, was less than 5 percent
greater36 than the area affected by the Day-Night Sound Level method.

Some Measurement Methods Provide Other Kinds of Noise Level Information

Two other measurement methods can provide additional kinds of information
about the noise exposure of a community. The Time-Above method can identify
how much time during a designated time period--such as a day--the noise
exposure levels will exceed a specified decibel level. The sound level must
be specified--for example, 60 decibels. This method can then determine the
length of time during a 24-hour period that noise levels will exceed 60
decibels.

To illustrate the Time-Above method, our model produced data on how many
minutes in a 24-hour day the noise levels would be above 60 and
80 decibels at points one-half mile from each end of the runway and at
1-mile increments from the runway for both approach and takeoff operations.
Table 4 illustrates the measures.

Table 4: Time-Above Noise Measurements for 60 and 80 A-weighted Decibels

                  Minutes per day               Minutes per day
                  above noise level--takeoff    above noise level--landing
 Miles from the
 runway           60 decibels   80 decibels     60 decibels   80 decibels
 1/2              143.2         34.3            81.6          20.0
 1                135           29.8            84.4          18.0
 2                124.2         21.8            90.1          12.8
 3                114.9         18.9            86.5          7.7
 4                106.3         15.2            76.2          0.4
 5                101.8         10.2            70.1          0.2
 6                95.1          8.7             62.0          0
 7                89.0          5.4             54.4          0
 8                84.3          3.9             44.3          0
 9                79.7          1.7             29.2          0
 10               74.7          0               26.9          0
 11               66.8          0               24.9          0
 12               63.9          0               22.4          0
 13               61.2          0               19.8          0
 14               59.8          0               16.6          0
 15               57.9          0               13.3          0
 16               55.4          0               8.7           0
 17               53.7          0               0.8           0
 18               51.3          0               0.7           0
 19               49.0          0               0.6           0
 20               46.2          0               0.6           0

Another variation of this kind of information is the Lpercent method, which
identifies the noise level exceeded for a portion of a time period. The
portion must be specified--for example, only 15 percent of a day. This
approach might determine, then, that for 15 percent of the day, the noise
level exceeded 60 decibels--that is, for the rest of the day the noise level
was at or below 60 decibels. FAA's Integrated Noise Model does not produce
measures using this method. Neither the Time-Above method nor this method
identifies the time of day the higher noise levels will occur.

Exposure

The Aviation Safety and Noise Abatement Act of 1979 required the Department
of Transportation--after consultation with the Environmental Protection
Agency--to establish, by regulation, a single system for measuring noise
from airports and surrounding areas. The act also required the Secretary to
establish a single method for measuring the exposure of individuals to noise
resulting from airport operations; that method had to consider noise
intensity, duration, frequency, and the time of occurrence. According to a
Senate committee report, the act was intended to establish a uniform
approach for measuring airport-related noise in order to facilitate the
administration of a federal noise abatement program that could, in turn,
lead to a uniform approach for dealing with noise problems in general.
Pursuant to that directive, in 1981, FAA selected the A-weighted decibel and
the Day-Night Sound Level method for measuring airport-related noise.37

In 1992, the Federal Interagency Committee on Noise noted that the Day-Night
Sound Level method was practical and widely accepted.38 After a
comprehensive review of measurement approaches, the interagency committee
determined that this method best met the statutory requirements. The
committee concluded that there were no other measurement methods of
sufficient scientific standing to replace this method as the primary
cumulative noise exposure measurement method and that the method correlates
well with analyses of community annoyance at various noise exposure
levels.39 The committee also noted that there were no new data to justify a
change in the use of extra weighting for nighttime operations. These
conclusions are still valid, according to the chairman of the Federal
Interagency Committee on Aviation Noise (the successor to the Federal
Interagency Committee on Noise), which focuses on aviation research related
to noise.

A frequent criticism levied against the Day-Night Sound Level method is that
it does not effectively convey to people what they can actually expect to
hear in any given area, primarily because it does not identify the noise
levels generated by single aircraft takeoffs or landings. The noise level
produced by the Day-Night Sound Level method is not the noise level that
people actually hear on an event by event basis--it is an average of the
cumulative sound levels over time.

To address this concern, the 1992 interagency committee report noted that
supplemental information--particularly information on noise generated by
individual takeoffs and landings--has been, and could continue to be,
useful, especially in characterizing specific events and in conveying a
clearer understanding of the potential effects of noise on people living and
working in the area. The interagency committee recommended that federal
agencies continue to be allowed to use supplemental information at their
discretion when dealing with environmental impact analyses and requirements.
An official of the interagency committee noted, however, that while single
event information is useful as a supplement, there is no methodology for
aggregating the effects of a single event into cumulative impact analysis,
as is the case with the Day-Night Sound Level method.

Because the interagency committee reiterated the usefulness of the Day-Night
Sound Level method, all federal agencies have adopted it for analyzing
airport-related noise in their environmental assessments and impact
statements. Some agencies, however, such as the Department of Defense, use
supplemental noise information, such as single event noise measures, to
provide a fuller picture of noise conditions and their potential effects. A
proposed revision to FAA's requirements for environmental analyses states
that FAA will also use supplemental information where warranted.40 The
revision adds new guidance on the kinds of supplemental information
available and their use.

Aircraft Noise Standards Vary By Aircraft Design and Do Not Apply to Some
Lighter Aircraft

FAA establishes the standards limiting the noise that civil subsonic
turbojet aircraft are permitted to generate.41 Those standards are generally
based on an aircraft's weight and the number of engines and generally allow
heavier aircraft to generate more noise than lighter aircraft. The statutory
deadline of December 31,1999, for compliance with "stage 3" standards did
not apply to aircraft weighing 75,000 pounds or less that were already in
operation. As of October 1, 1999, more than 2,750 aircraft were not subject
to the stage 3 compliance deadline.

Noise Than Lighter Aircraft

FAA regulations establish the maximum noise levels that civil subsonic
turbojet aircraft are allowed to generate for takeoff, landing, and
"sideline" measurements. The standards for each of these kinds of
measurements are different, but, in general, these standards vary with the
weight of the aircraft. The standards allow heavier aircraft to be noisier
than lighter aircraft because, according to FAA, the noise generated by an
aircraft is generally determined by the thrust powering the aircraft; the
amount of thrust an aircraft needs is proportional to the weight of the
plane--that is, the heavier the aircraft, the more thrust it needs.42
According to an aircraft noise expert, lower noise standards for lighter
aircraft is one of the reasons that a stage 2 aircraft weighing 75,000
pounds or less may make less noise than a heavier aircraft that meets the
more stringent stage 3 standards. For takeoff, stage 3 noise standards also
vary on the basis of the number of engines; generally, the more engines an
aircraft design has, the higher the permitted takeoff noise levels. Stage 3
standards for takeoff, sideline, and approach are shown in appendix VII.

The United States is a member of the International Civil Aviation
Organization--the international authority on civil aviation standards--and
as such participates in that organization's activities regarding aircraft
noise standards. Members of the organization--are considering more stringent
noise standards. The organization's Committee on Aviation Environmental
Protection is reviewing several options, identified by its Noise Scenarios
Group in a November 1999 report, including: (1) taking no action on more
stringent standards, (2) adopting a standard only for new aircraft designs,
or (3) adopting more stringent standards with various schedules for the
phaseout of noisier aircraft. Guidance governing the Committee's work
directs it to consider such factors as technical feasibility, economic
reasonableness, and the environmental benefit to be achieved. The
organization is expected to adopt a resolution when it meets in September
2001 on a more stringent standard and the phaseout of stage 3 aircraft.
Implementation of the new standard, and phaseout of the noisier aircraft,
would be up to the member nations.43

The European Union has banned, after May 1, 2000, stage 2 aircraft that were
modified to meet stage 3 noise standards,44 unless the aircraft were already
operating or registered in a member country before that date. The European
Union also adopted restrictions on operating modified aircraft after April
1, 2002. The United States filed a formal complaint with the International
Civil Aviation Organization on March 14, 2000, alleging that the European
Union's ban discriminates against U.S. aircraft in violation of the
agreement establishing the organization.

From Operating Restrictions

Both stage 1 and stage 2 aircraft that did not meet more stringent noise
standards by specified dates have been prohibited from operating after those
deadlines, but that prohibition does not apply to aircraft in service that
weigh 75,000 pounds or less. FAA did not require the retirement of the
lighter stage 1 aircraft that did not meet stage 2 standards because FAA
concluded it was not technologically practicable or economically reasonable
to modify these aircraft. The statute prohibiting the operation of stage 2
aircraft that did not meet stage 3 standards by a certain date does not
apply to aircraft weighing 75,000 pounds or less.

and Economic Reasons

When FAA amends regulations controlling aircraft noise, it must consider
several factors, including whether the proposed regulations are
technologically practicable, economically reasonable, and appropriate for
the types of aircraft, aircraft engines, or aircraft certifications that the
regulations apply to.45 FAA must also consider the extent to which any
proposed amendments protect the public health and welfare.

In 1976, FAA considered amending its regulations to require stage 1 aircraft
already in service to meet stage 2 noise standards or be prohibited from
operating at U.S. airports. At that time, the Environmental Protection
Agency recommended that the deadline for compliance be applied to all civil
subsonic turbojet aircraft regardless of weight. That agency contended that
all of those aircraft were capable of meeting stage 2 standards by using
various engine modifications or replacement options. It determined that
because all newly produced aircraft weighing
75,000 pounds or less had to comply with stage 2 noise standards after
January 1, 1975, there seemed to be no valid justification for permitting
stage 1 aircraft to operate indefinitely. While some who commented on FAA's
proposed amendment supported the Environmental Protection Agency's
conclusion, others challenged it, contending, for example, that
(1) the technology was not available to enable lighter aircraft to meet the
stage 2 noise standards or (2) other sources, such as heavier aircraft or
traffic from regularly scheduled passenger service flights, were the primary
causes of the noise problems.

FAA chose not to apply the operating deadline for stage 1 aircraft to
aircraft weighing 75,000 pounds or less. FAA concluded that it could not
impose operating noise limits on the lighter aircraft at that time in a
manner that was fully consistent with its obligations under the law for two
reasons. First, FAA determined that the cost-effectiveness of implementing
the kinds of modifications needed to retrofit an existing aircraft was
questionable and, therefore, not technologically practicable. It concluded
that noise reduction modifications to the lighter aircraft could be applied
during the original design and manufacture of an aircraft, but such
modifications involved substantial redesign efforts that, while reasonable
when spread over the production process, were of doubtful cost-effectiveness
if accomplished by retrofitting. FAA considered only retrofitting
options--engine modification or replacement--as acceptable for meeting noise
standards; flight operation noise abatement procedures were not an
acceptable means for complying with the noise standards.46

Second, FAA determined that available information was not sufficient to
assess the economic impact on owners of an across-the-board requirement to
retrofit the lighter aircraft. Available information was limited because the
aircraft were so varied in their use and mission and were frequently the
only--or one of a few--aircraft owned by the owner. In addition, FAA
determined that the availability of supplies for small engine manufacturers
needed further study before FAA could assess the overall economic impact of
specific compliance dates on aircraft owners.

In December 1997, however, the National Business Aviation Association, a
membership organization of companies that operate aircraft, passed a
resolution calling for the group's 5,200 members to refrain from adding new
stage 1 aircraft to their fleets beginning in January 2000 and to end the
operation of stage 1 aircraft by 2005.

Stage 2 Retirement Did Not Apply to the Lighter Aircraft

The Airport Noise and Capacity Act of 1990 established December 31, 1999, as
the deadline for phasing out stage 2 aircraft that were not modified to meet
stage 3 noise standards. The statute, however, specifically applied the
phaseout only to aircraft weighing more than 75,000 pounds. The legislative
history of the act provides no discussion on why the statutory phaseout was
not applied to the lighter aircraft.47 As of October 1, 1999, just over
9,000 civil subsonic turbojet aircraft that weighed 75,000 pounds or less
were certified by FAA as airworthy.48 About 31 percent of those, or just
over 2,770, are stage 1 or stage 2 aircraft that may still operate at U.S.
airports after December 31, 1999.

The 1990 act, however, also established federal review requirements when an
airport wants to control noise by imposing more stringent limitations on
aircrafts' use of the airport than federal regulations provide. The act
directed the Secretary of Transportation to establish a national program for
reviewing airport restrictions on the operation of stage 2 and stage 3
aircraft. It also required the Secretary to study whether federal review
should be applied to restrictions on stage 2 aircraft weighing less than
75,000 pounds. The study recommended that the same procedures should apply
to all stage 2 aircraft, regardless of weight.49 FAA adopted that
recommendation. Thus, an airport may impose a noise or access restriction on
stage 2 aircraft, whatever its weight, if the airport operator publishes the
proposed restriction and prepares and makes certain analyses available for
public comment at least 180 days before the effective date of the
restriction.50 Unlike noise or access restrictions proposed for stage 3
aircraft, FAA approval is not required.

FAA's Land Use Planning Initiative Focuses First on Improving Access to
Information

Land use planning is one way that communities can alleviate the impact of
airport-related noise in areas near airports. While the federal government
has no decision-making authority in land use planning, FAA does have some
responsibility to address land use issues in connection with its
administration of airport-related noise programs. For example, as required
by law, FAA has identified the kinds of land uses that are compatible with
various noise levels communities may be exposed to because of a nearby
airport. Looking to the future, FAA has announced five short-term actions
under its Land Use Planning Initiative, which it launched to help prevent
incompatible land uses. Reviewing the comments provided by the aviation
sector and the general public, we identified four principal areas of concern
associated with the initiative.

Through land use planning, communities determine what kinds of
development--for example, residential or industrial--will occur within their
jurisdictions. Communities can use such land use planning to reduce or
alleviate the impact of airport-related noise. For example, communities may
prohibit the construction of schools within a certain distance from an
airport so that airport-related noise will not interrupt classes. While the
federal government has no direct decision-making authority over land use
planning, FAA can nevertheless help communities consider the impact of
nearby airports as they develop their plans. For example, the Aviation
Safety and Noise Abatement Act of 1979 requires FAA to identify land uses
that would not be compatible with noise generated by the operation of a
nearby airport. As a result, FAA identified some land uses, such as homes
and schools, as being incompatible with noise exposure levels of
65 decibels or higher (using the Day-Night Sound Level method) that occur
very close to an airport, while other land uses, such as industrial and
commercial uses, could successfully be located close to an airport without
interfering with activity.51 Although FAA can provide land use planning
guidance, it is up to the state and to local communities to apply this
guidance.

The recent transition to quieter aircraft can lower noise exposure levels in
some communities, but FAA has been concerned that noise levels may rise
again around some airports if the number of flights increase to meet the
expected growth in passenger levels.52 According to an FAA official, even
where noise levels do not rise, maintaining a buffer zone between the
airport and certain land uses, such as homes and schools, serves a general
interest in maintaining a quieter environment. Because of its concerns, FAA
embarked on a Land Use Planning Initiative to help state and local
governments achieve and maintain compatible land uses around airports. Under
this Initiative, in January 1995, FAA sponsored a Study Group on Compatible
Land Use, which was composed of community, airport, and aviation
representatives. This group recommended federal actions that could promote
compatible land use planning around airports. In May 1998, FAA issued a
request in the Federal Register for additional suggestions to help state and
local governments' planning efforts. After reviewing the submissions, FAA
announced in May 1999 that it would implement five short-term actions while
it continued its review of other suggestions. FAA expects to announce
additional actions in the future on training, education, satellite
navigation, research and development, and proposed legislation.

The five short-term actions that FAA announced in May 1999 focus primarily
on improving the communication of its noise policies and noise compatibility
information in order to help communities and airports work together to
minimize the noise impacts of airports. Table 5 provides an overview of each
action, the FAA office responsible for implementation, and the
implementation status of each action.

Table 5: Short-term Actions Under FAA's Land Use Planning Initiative

 Action                           Responsible FAA   Implementation status
                                  office
 Develop a package of land use
 planning information for use by
 FAA regional officials and
 national planning organizations,
 primarily at local meetings. The
 package is to include
 information on FAA's noise
 policies; effects of a           Office of
 transition to quieter aircraft;  Environment and   Implementation goal--
 testimony on noise issues and    Energy            March 31, 2000a
 planning; examples of local
 zoning and information
 disclosure rules; and methods
 through which compatible land
 use development can be achieved
 around airports; and other
 pertinent information.
 Develop an information package
 on existing statutes for state   Office of
 aviation organizations through   Environment and   Implementation goal--
 the National Association of      Energy            March 31, 2000a
 State Aviation Officials.b
 Provide an information
 clearinghouse--readily
 accessible to federal, state,
 local, industry and public                         An Internet website was
 users--for compatible land use                     created, enabling the
 planning information, including  Office of Airport agency to meet the
 FAA orders, advisory circulars,  Planning and      original implementation
 reports, studies, and other      Programming       goal of September 30,
 related information; and access                    1999.
 to available land use planning
 resources that are applicable to
 aviation.
 Use a rapid-response procedure
 within the agency to respond
 quickly to inquiries on FAA
 policies. This procedure would   Office of
 include a mechanism to assist    Environment and   Implementation goal--
 airports, jurisdictions, and/or  Energy            March 31, 2000a
 communities attempting to
 resolve conflicts between
 airport and community needs.
 Provide clearer understanding of
 what FAA might do to address
 noise exposure, particularly in
 relation to areas exposed to                       FAA revised its order
 noise levels below the 65                          in
 decibel level--the level at                        June 1999 that provides
 which all land uses are                            guidance on
 currently considered             Office of         environmental impact
 compatible--and in areas outside Environment and   analyses concerning
 the airport's direct control.    Energy            airports, enabling the
 FAA actions include providing                      agency to meet the
 greater FAA focus on the use of                    original implementation
 in-flight procedures to achieve                    goal of September 30,
 noise abatement, and more                          1999.
 consultations with airports and
 communities in those lower
 exposure areas.

aThe first anticipated implementation date was Sept. 30, 1999. As of Apr.
26, 2000, an FAA official stated that the actions were expected to be fully
implemented by May 2000.

bThis is a member organization representing the aviation departments/units
in each of the 50 states, as well as Puerto Rico and Guam.

The implementation goal for these short-term actions was originally
September 30, 1999. FAA has completed implementation of two of these
actions. To establish the information clearinghouse, FAA created an Internet
website. To provide a clearer understanding of its actions addressing
certain noise exposure situations, FAA issued revisions in June 1999 to its
order that provides guidance on conducting environmental impact analyses for
airports. The November implementation goal for the remaining three actions
was delayed until March 31, 2000, primarily because FAA was reorganizing its
Office of Environment and Energy, which is responsible for the Land Use
Planning Initiative. As of April 26, 2000, an FAA official expected the
remaining actions to be implemented by
May 2000.

The clearinghouse that FAA established on land use information can be
accessed at www.faa.gov/arp/app600/5054a/landuse.htm. According to FAA
officials, this website will become the primary means for distributing
information made available by some of these short-term actions--including
the information packages--and any additional actions approved in the future.
The website has links to information on Washington State's website for its
land use planning program and will eventually link to other states that have
similar websites. It also incorporates links to websites for land use
planning associations, periodicals, and legal planning specialists. FAA
plans to add information and/or links as warranted.

FAA stated that the objectives of its fifth action include (1) providing
greater focus on the use of flight procedures to mitigate the effects of
noise over certain areas and (2) emphasizing consultations with airports and
communities. FAA's overall goal is to clarify the actions it might take to
address rising noise exposure levels. FAA's revised guidance, however, does
not appear to achieve its objective of providing greater focus on the use of
flight procedures because the revisions contain no explicit discussion of
the use of flight procedures to mitigate the effects of noise over certain
areas. Furthermore, this lack of discussion contrasts with the detailed
description FAA provides to incorporate other changes to that same order,
including changes pending that pertain to the use of supplemental
information in environmental impact analyses.

In reviewing the public comments on the Initiative and from our discussions
with aviation officials and other experts, we identified four principal
areas of concern associated with the Initiative. These areas involve
determining (1) what is the most effective use of the agency's limited
resources when addressing airport-related noise, (2) whether the
65 decibel level defining incompatible land uses should be lowered,
(3) whether additional information, such as single event noise levels,
should be required when analyzing noise impacts, and (4) what is the best
use of federally authorized investment in the growth of airport capacity in
view of the noise and physical expansion constraints affecting many
airports.53 Table 6 summarizes the context and scope of these issues.

Table 6: Summary of Key Land Use Planning Issues Related to Airport Noise

       Issue            Context of issue             Scope of issue
                                              Some in the aviation
                                              community support a proactive
                                              role for FAA in land use
                                              planning and even suggest
                                              that FAA should expand its
                                              efforts to include other
                                              activities, such as playing
                                              an active role to support
                                              state legislation on
                                              compatible land use and
                                              community land use planning
                                              processes. Others question
                                              FAA's focus on land use
                                              planning when the agency has
                                              no direct jurisdiction over
                                              it. Some suggest that FAA
 Should FAA's role                            should focus on those
 in land use                                  activities over which it has
 planning be more     FAA has no direct       authority, such as changing
 proactive or         jurisdiction over       flight paths or mandating new
 should it focus      land use or zoning      aircraft noise reductions.
 its limited          decision-making.
 resources on         Zoning authority is
 activities over      the province of state
 which it has         and local               FAA officials believe that
 direct               governments.            land use planning is an
 jurisdiction?                                important way to prevent
                                              noise problems. They are
                                              concerned that noise
                                              reductions resulting from
                                              transition to quieter
                                              aircraft will spur
                                              development in areas closer
                                              to airports that later may
                                              experience higher noise
                                              exposure levels because of
                                              growth in aviation or may
                                              raise concerns even where
                                              noise levels remain stable.
                                              Preventing future
                                              incompatible land use will
                                              reduce future noise
                                              mitigation costs.
                                              Some interested parties,
                                              particularly community and
                                              environmental groups as well
                                              as individuals, believe that
                      FAA's regulations       the noise exposure level
                      establish a noise       below which all land uses are
                      exposure level below    compatible is too high and
                      which all land uses     should be lowered. This is
                      are considered          also a particular concern
                      compatible with         because that level has a very
                      airport-related noise   strong influence on FAA's
 Should the noise     and above which         decisions about which noise
 level defining all   residential and         abatement efforts to fund.
 land uses as         certain other
 compatible be        development is
 lowered or           considered
 retained at the      incompatible with       An FAA official noted that
 65 decibel           that noise. FAA uses    there are not enough
 Day-Night Sound      that level to help      federally authorized funds to
 Level measure?       set priorities for      pay for all planned or
                      funding decisions for   approved noise mitigation
                      noise abatement         efforts so FAA uses the
                      projects, resulting     compatible land use noise
                      in few projects being   exposure level to help focus
                      approved where all      funds in the most
                      land uses are           noise-impacted areas. The
                      compatible under        official noted that FAA does
                      federal guidelines.     approve the funding of
                                              projects where the noise
                                              exposure level is lower, when
                                              warranted, but that very few
                                              have been approved.
                                              Because of the way noise
                                              exposure levels are measured,
                                              the numerical values involved
                                              can be lower than the
                                              measured value of noise
                                              generated by a single
                                              aircraft's takeoff or
                                              landing. As a result,
                                              interested groups and
                                              individuals suggest that
                      The law requires FAA    additional information be
 Should the use of    to establish a single   available and be used in
 supplemental         method for measuring    assessing the noise exposure
 information, such    the noise exposure      levels in communities for
 as single event      levels in communities   federal funding and land use
 noise measures, be   surrounding airports.   compatibility determinations.
 required when        At their discretion,
 measuring noise      federal agencies
 impacts for          provide or use
 environmental        supplemental            FAA is required by law to
 impact analyses of   information in          select one measurement of
 airport              implementing their      community noise exposure. The
 development          programs that involve   Federal Interagency Committee
 projects?            assessing noise         on Noise noted in a 1992
                      exposure levels.        report that there is no
                                              accepted methodology for
                                              aggregating single event
                                              noise levels to explain the
                                              cumulative impact on people
                                              in communities near airports.
                                              Proposed revisions to an FAA
                                              order recognize the
                                              usefulness of supplemental
                                              information where warranted,
                                              whereas before FAA policy was
                                              only to consider its use.
                                              In view of the noise issues
                                              at many airports, as well as
                                              the physical constraints
                                              affecting capacity expansion
                                              at many airports,
                                              some--particularly
                                              individuals and
                                              community/environmental
                                              groups--suggest that FAA
 How should                                   should direct airport
 federally            FAA approves            expansion funds to existing
 authorized           federally authorized    or new airports that are not
 investment in        funding for projects    affected by noise or
 airport capacity     to expand airport       geographic constraints.
 growth be            capacity. Forecast
 directed, given      growth in the demand
 the noise and        for air travel is
 physical expansion   pressuring airports     Proposals for airport
 constraints facing   to expand capacity to   expansion originate at the
 so many of the       meet that future        local level. Private sector
 nation's large       demand.                 decisions, such as an
 airports?                                    airline's selection of hub
                                              airports, also affect
                                              airports' plans for
                                              expansion. FAA approves
                                              funding for airport
                                              infrastructure projects
                                              pursuant to the provisions of
                                              the Airport Improvement
                                              Program and the Passenger
                                              Facility Charge program.a

a See Airport Financing: Funding Sources for Airport Development
(GAO/RCED-98-71 , Mar. 1998) and Passenger Facility Charges: Program
Implementation and the Potential Effects of Proposed Changes
(GAO/RCED-99-138, May 1999).

Through its responsibilities for aviation noise, FAA plays a critical role
in helping to reduce the noise that airports generate and to mitigate the
effects of that noise on surrounding communities. While FAA has accomplished
much in fulfilling its statutory responsibilities, the issues raised in
connection with FAA's Land Use Planning Initiative are not necessarily new
and show that more work remains to be done on resolving controversies
regarding airport-related noise. Addressing these issues will require
balancing the needs of the different--and often conflicting--interests of
airports, airlines, manufacturers, passengers, general aviation, and the
communities near the airports. Resolution of these issues will also need to
take into account concerns about the environment, as well as advances in
technology.

We provided the Department of Transportation, the National Association of
State Aviation Officials, an advisory panel of five experts, the Airports
Council International-North America, the General Aviation Manufacturers
Association, and the Air Transport Association of America, Inc. with copies
of the draft report for their review and comment.

We met with officials from the Department of Transportation, including FAA's
Manager, Community and Environmental Needs Division, and spoke with FAA's
Manager, Noise Division. These officials generally agreed with the facts in
the report and provided clarifying comments, which we incorporated as
appropriate. The National Association of State Aviation Officials and the
advisory panel of experts generally agreed with the facts in the report and
provided us with technical and clarifying comments, which we incorporated as
appropriate. The Airports Council International-North America provided no
comments.

We spoke with the President of the General Aviation Manufacturers
Association, who stated that the report reflects a good effort to make a
difficult topic understandable. However, he said the Association had three
concerns about the accuracy of the presentation. The Association believes
the draft report (1) implied that aircraft not subject to phased compliance
with operating noise limits were not subject to any noise standards, when in
fact, all aircraft manufactured after December 31, 1974, must meet
stage 3 noise standards; (2) did not explain that the exception of lighter
aircraft from compliance with stage 3 operating noise limits was consistent
with international operating rules developed by the International Civil
Aviation Organization; and (3) overestimated how many aircraft weighing
75,000 pounds or less still operate in the United States. The Association
further believed the general aviation aircraft selected for our airport
model were not representative of the operating fleet.

With regard to the Association's first concern, we believe the draft report
accurately explained the progressive application of noise standards to
aircraft. However, we revised it to clarify the distinction between noise
standards for the certification of aircraft as airworthy and the application
of those standards to operating aircraft. Regarding the second concern, this
report focuses on FAA's roles and responsibilities rather than on
international activities. Nevertheless, we revised the draft report to
clarify that the United States is a member of the International Civil
Aviation Organization and as such participates in that organization's
activities regarding aircraft noise standards. Concerning the final issue,
data in our draft report on the number of aircraft weighing 75,000 pounds or
less include all such aircraft certificated by FAA as airworthy as of
October 1, 1999. In contrast, data provided by the Association include only
the operating business fleet, which is a subset of FAA's list of
certificated aircraft. With regard to our selection of aircraft for the
model, we began with the universe of certificated aircraft and selected two
general aviation aircraft from this list, as well as four others, to reflect
both stage 2 and stage 3 aircraft, and lighter and heavier aircraft. We
revised the draft report to clarify that we selected aircraft from the list
of certificated aircraft.

We met with officials from the Air Transport Association of America, Inc.,
who stated that the draft report was generally very good, but who expressed
five concerns. They believe the draft report (1) did not fully recognize, in
its discussion of the potential impact of growth in air traffic, the
significant progress that the Congress, FAA, airports, and the airlines have
made in reducing the number of people exposed to noise from aircraft, nor
did it recognize that aircraft used to achieve additional growth may be
quieter; (2) did not fully reflect the role of international agreements and
obligations related to noise control; (3) was overly broad in its discussion
of flight procedures for abating noise when explaining why FAA did not
require aircraft weighing 75,000 pounds or less to be retired if they did
not meet stage 2 standards; (4) included only two aircraft in the airport
model, one of which is no longer being produced, and did not address current
production aircraft; and (5) did not fully reflect the relationship and
potential trade-offs between noise stringency standards and aircraft
emissions. The Association also provided technical and clarifying comments,
which we incorporated as appropriate.

With regard to the first concern, we agree that the aviation industry and
the federal government have made substantial progress in reducing noise
generated by airports. However, forecast growth in aviation activity could
reduce or eliminate the benefits at individual airports. If current aircraft
are replaced with quieter aircraft, the impact of the quieter aircraft on
airport-related noise will depend on several factors including the extent to
which aircraft operations increase and when operations occur. We revised the
draft report to clarify these points.

With regard to the second issue, we agree that the international
administrative and regulatory framework for developing and implementing
aircraft noise standards is important for the aviation industry. However,
this report focuses on FAA's role in major noise-related programs rather
than on international activities. Nevertheless, we revised the draft report
to clarify that the United States is a member of the International Civil
Aviation Organization and as such participates in that organization's
activities regarding aircraft noise standards.

Regarding the third concern, our draft report provided FAA's rationale for
not applying a retirement deadline to stage 1 aircraft weighing
75,000 pounds or less. As noted in the report, FAA did not consider flight
operations to be an appropriate operational noise abatement procedure for
the purpose of meeting aircraft noise standards. As also noted, however, FAA
did consider flight operations to be appropriate for further reducing noise
where circumstances warrant. Accordingly, we did not revise this discussion
in our draft report.

With regard to the fourth concern, the Association incorrectly concluded
that the airport model included only two aircraft. As appendix V of the
report explains, the model was designed to provide a reasonable facsimile of
an airport for use in comparing and illustrating the various noise
measurement methods. Six aircraft were selected from FAA's list of
certificated aircraft to represent categories of aircraft operations.
Aircraft selection was not intended to include only those aircraft currently
in production because that would have eliminated stage 2 aircraft from the
model.

With regard to the final concern, we revised the draft report to acknowledge
that reducing aircraft noise may result in higher aircraft emissions.

Process for Participating in the Part 150 Noise Compatibility Program

The first step in preparing a noise compatibility program is to develop
noise exposure maps that identify incompatible land uses. The airport must
provide a map that shows the present noise exposure levels and a second map
that shows projected noise exposure levels based on anticipated airport
operations 5 or more years into the future. Once the Federal Aviation
Administration (FAA) accepts the maps as complying with regulatory and
technical requirements, it publishes a notice of compliance in the Federal
Register. If the airport makes any operational changes that would increase
the noise level by 1.5 decibels or more in areas with incompatible land
uses, the airport must submit a revised noise exposure map. Figure 8
illustrates the preparation, review, and acceptance process for noise
exposure maps.

Figure 8: Part 150 Noise Exposure Map Preparation and Acceptance Process
Note: Noise exposure maps identify airport runways; flight tracks; noise
contours for at least 65, 70, and 75 decibels; airport boundaries;
incompatible land uses; any optional aircraft noise monitoring sites; and
location of noise sensitive public buildings such as schools, churches, and
hospitals.

Airports interested in developing a noise compatibility program may
generally submit noise exposure maps for FAA's acceptance at the same time
that they submit their overall noise compatibility program for FAA's
approval.54 The noise compatibility program is intended to show the measures
the airport has taken, or proposes to take, to reduce incompatible land uses
and to prevent the introduction of additional incompatible uses in the
future. According to FAA, the noise compatibility program is the primary
vehicle for guiding and coordinating all those whose combined efforts are
essential to achieve the maximum degree of noise compatibility between the
airport and its neighbors while taking into account the requirements of the
national aviation system. Figure 9 illustrates the preparation, review, and
approval process for noise compatibility programs. 55

Figure 9: Part 150 Noise Compatibility Program Preparation and Approval
Process
aAn airport may submit its noise exposure maps along with the noise
compatibility program.

bFAA's evaluation of all proposed measures includes whether they are
reasonably consistent with the goals of reducing or preventing incompatible
land uses and ensuring that they do not create an undue burden on interstate
commerce, adversely affect aircraft safety or efficiency, or otherwise
adversely affect any other powers and duties of the FAA administrator.

cFlight operational changes--including actual operations as well as measures
related to flight procedures, such as navigational aids--are not subject to
the 180-day approval requirement.

National Priority System for AIP-Eligible Projects

FAA ranks all projects eligible for the Airport Improvement Program (AIP)
according to its national priority system in order to identify those of
sufficient national interest to warrant federal funding. A priority ranking
formula serves as an initial screening of all AIP-eligible projects. Under
the formula, priority rating = (0.25 x purpose) x [(1 x airport size) + (1.4
x purpose) + (1 x component) + (1.2 x type)]. Each of the four elements in
the formula--purpose, airport size, component, and type--has assigned point
values consistent with FAA's goals and objectives. The point values assigned
are listed in tables 7 through 10. FAA also considers other factors--such as
benefit-cost analyses, risk assessment, regional priorities, state and
metropolitan system plans, airport growth, and market forces--in determining
a project's overall ranking.

Table 7: Point Values Assigned for Project Purpose in FAA's National
Priority System

 Points Type of purpose
 10     Safety/security
 9      Statutory emphasis program

 8      Environment (including Part 150), planning,
        reconstruction/rehabilitation
 7      Capacity
 6      Standards

 4      Other--such as people movers, rail systems, access roads, parking
        lots, fuel farms, training systems.

Table 8: Point Values Assigned for Airport Size in FAA's National Priority
System

 Points Size of airport

 5      Large-and medium-hub airports, other commercial service and general
        aviation airports with 100 based aircraft or 50,000 operations

 4      Small and nonhub airports, other commercial service and general
        aviation airports with 50 based aircraft or 20,000 operations

 3      Other commercial service and general aviation airports with 20
        based aircraft or 8,000 operations
        Other commercial service and general aviation airports with less
 2      than
        20 based aircraft or less than 8,000 operations

Table 9: Point Values Assigned for the Component Element in FAA's National
Priority System

 Points    Type of component
 10        Runway
 9         Helipad, seaplane
 8         Equipment, taxiway
           Homes--residential noise mitigation; land; other, such as fuel
 7         farms and airport drainage, public buildings--noise mitigation,
           planning
 5         Apron

 4         Transportation--people movers and rail/road access, new airport,
           vertiport
 3         Building
 1         Terminal
 0         Bond retirement financing

Table 10: Point Values Assigned for Project Type in FAA's National Priority
System

 Points    Category of type
           Noise projects in 75-decibel day-night sound level and above,
 10        construction, obstruction removal, aircraft rescue fire fighting
           vehicle

 9         Runway friction, master planning, runway/taxiway signs, snow
           removal equipment
           Improvement to existing infrastructure, lighting, runway safety
 8         area, sensors, state planning, safety zone, visual approach aid,
           weather reporting equipment
           Noise projects in 70- to 74-decibel day-night sound level,
 7         access to airport, instrument approach aid, metropolitan
           planning, noise plan/suppression

 6         De-icing facility, development-land, extension/expansion,
           environmental mitigation, security, airport service road
 5         Acquire airport, miscellaneous
 4         Noise projects in 65- to 69-decibel day-night sound level
 3         People mover, rail

 2         Fuel farm development, plan to construct a vertical take off and
           landing runway/vertiport
 1         Automobile parking

 0         Noise projects in day-night sound level below 65 decibels,
           administrative costs, bond retirement

Funding for Noise-Related Projects Through the Airport Improvement Program,
Fiscal Years 1982 Through 1999

Table 11 provides the amount of AIP grants awarded for noise-related
projects by type of project and by fiscal year, for fiscal years 1982
through 1999. As the table shows, the amount has varied from a low of $35.6
million in fiscal year 1982 to a high of $254.4 million in fiscal year 1993.

Table 11: Noise-related Projects Funded Through the Airport Improvement
Program, Fiscal Years 1982 Through 1999, by Project Type

Continued from Previous Page

          Dollar in thousands
      Project type and fiscal year        Amount    Percent
 1982
 Land for noise control                 $32,392     91.1
 Landscaping                            0           0
 Lighting                               0           0
 Miscellaneous                          0           0
 Navigational aids                      0           0
 Noise barrier                          194         0.5
 Planning                               637         1.8
 Noise-suppressing equipment            0           0
 Relocation assistance                  1,193       3.4
 Runway development                     1,146       3.2
 Soundproofing                          0           0
 State grant                            0           0
 Taxiway development                    0           0
 Fiscal year total                      $35,563     100
 1983
 Land for noise control                 $51,478     80.3
 Landscaping                            0           0
 Lighting                               270         0.4
 Miscellaneous                          1,142       1.8
 Navigational aids                      0           0
 Noise barrier                          0           0
 Planning                               1,476       2.3
 Noise-suppressing equipment            0           0
 Relocation assistance                  6,017       9.4
 Runway development                     0           0
 Soundproofing                          3,759       5.9
 State grant                            0           0
 Taxiway development                    0           0
 Fiscal year total                      $64,142     100
 1984
 Land for noise control                 $49,210     67.1
 Landscaping                            0           0
 Lighting                               187         0.3
 Miscellaneous                          673         0.9
 Navigational aids                      0           0
 Noise barrier                          632         0.9
 Planning                               2,938       4.0
 Noise-suppressing equipment            0           0
 Relocation assistance                  5,357       7.3
 Runway development                     6,624       9.0
 Soundproofing                          6,120       8.3
 State grant                            0           0
 Taxiway development                    1,588       2.2
 Fiscal year total                      $73,330     100
 1985
 Land for noise control                 $57,754     67.8
 Landscaping                            0           0
 Lighting                               45          0.1
 Miscellaneous                          661         0.8
 Navigational aids                      20          0.0a
 Noise barrier                          511         0.6
 Planning                               5,099       6.0
 Noise-suppressing equipment            0           0
 Relocation assistance                  6,007       7.1
 Runway development                     3,848       4.5
 Soundproofing                          8,860       10.4
 State grant                            0           0
 Taxiway development                    2,316       2.7
 Fiscal year total                      $85,121     100
 1986
 Land for noise control                 $59,351     59.6
 Landscaping                            196         0.2
 Lighting                               0           0
 Miscellaneous                          768         0.8
 Navigational aids                      0           0
 Noise barrier                          625         0.6
 Planning                               4,196       4.2
 Noise-suppressing equipment            115         0.1
 Relocation assistance                  4,535       4.6
 Runway development                     2,435       2.4
 Soundproofing                          23,124      23.2
 State grant                            0           0
 Taxiway development                    4,154       4.2
 Fiscal year total                      $99,499     100
 1987
 Land for noise control                 $48,385     65.4
 Landscaping                            0           0
 Lighting                               0           0
 Miscellaneous                          2,324       3.1
 Navigational aids                      0           0
 Noise barrier                          210         0.3
 Planning                               3,050       4.1
 Noise-suppressing equipment            0           0
 Relocation assistance                  7,190       9.7
 Runway development                     156         0.2
 Soundproofing                          12,688      17.1
 State grant                            0           0
 Taxiway development                    0           0
 Fiscal year total                      $74,003     100
 1988
 Land for noise control                 $76,743     50.0
 Landscaping                            0           0
 Lighting                               24          0.0a
 Miscellaneous                          2,662       1.7
 Navigational aids                      0           0
 Noise barrier                          0           0
 Planning                               4,383       2.9
 Noise-suppressing equipment            0           0
 Relocation assistance                  13,162      8.6
 Runway development                     6,030       3.9
 Soundproofing                          47,487      30.9
 State grant                            0           0
 Taxiway development                    3,147       2.0
 Fiscal year total                      $153,638    100
 1989
 Land for noise control                 $82,511     59.0
 Landscaping                            0           0
 Lighting                               2,171       1.6
 Miscellaneous                          306         0.2
 Navigational aids                      50          0.0a
 Noise barrier                          4,171       3.0
 Planning                               2,540       1.8
 Noise-suppressing equipment            0           0
 Relocation assistance                  4,796       3.4
 Runway development                     3,230       2.3
 Soundproofing                          35,910      25.7
 State grant                            0           0
 Taxiway development                    4,152       3.0
 Fiscal year total                      $139,838    100
 1990
 Land for noise control                 $96,022     62.2
 Landscaping                            0           0
 Lighting                               371         0.2
 Miscellaneous                          345         0.2
 Navigational aids                      0           0
 Noise barrier                          0           0
 Planning                               1,636       1.1
 Noise-suppressing equipment            26          0.0a
 Relocation assistance                  11,398      7.4
 Runway development                     7,582       4.9
 Soundproofing                          27,546      17.8
 State grant                            2,800       1.8
 Taxiway development                    6,621       4.3
 Fiscal year total                      $154,348    100
 1991
 Land for noise control                 $113,891    56.0
 Landscaping                            0           0
 Lighting                               336         0.2
 Miscellaneous                          3,542       1.7
 Navigational aids                      0           0
 Noise barrier                          115         0.1
 Planning                               2,854       1.4
 Noise-suppressing equipment            0           0
 Relocation assistance                  13,263      6.5
 Runway development                     5,408       2.7
 Soundproofing                          54,955      27.0
 State grant                            3,000       1.5
 Taxiway development                    5,968       2.9
 Fiscal year total                      $203,330    100
 1992
 Land for noise control                 $104,530    52.4
 Landscaping                            0           0
 Lighting                               1,299       0.7
 Miscellaneous                          0           0
 Navigational aids                      0           0
 Noise barrier                          234         0.1
 Planning                               2,738       1.4
 Noise-suppressing equipment            980         0.5
 Relocation assistance                  19,119      9.6
 Runway development                     66          0.0a
 Soundproofing                          65,884      33.0
 State grant                            1,912       1.0
 Taxiway development                    2,808       1.4
 Fiscal year total                      $199,569    100
 1993
 Land for noise control                 $141,092    5.55
 Landscaping                            0           0
 Lighting                               0           0
 Miscellaneous                          3,762       1.5
 Navigational aids                      0           0
 Noise barrier                          2,877       1.1
 Planning                               3,293       1.3
 Noise-suppressing equipment            250         0.1
 Relocation assistance                  27,609      10.9
 Runway development                     33          0.0a
 Soundproofing                          73,716      29.0
 State grant                            1,800       0.7
 Taxiway development                    0           0
 Fiscal year total                      $254,432    100
 1994
 Land for noise control                 $118,270    51.6
 Landscaping                            0           0
 Lighting                               0           0
 Miscellaneous                          1,590       0.7
 Navigational aids                      0           0
 Noise barrier                          0           0
 Planning                               4,367       1.9
 Noise-suppressing equipment            740         0.3
 Relocation assistance                  16,922      7.4
 Runway development                     13,011      5.7
 Soundproofing                          72,557      31.7
 State grant                            1,698       0.7
 Taxiway development                    0           0
 Fiscal year total                      $229,154    100
 1995
 Land for noise control                 $81,304     49.3
 Landscaping                            640         0.4
 Lighting                               40          0.0a
 Miscellaneous                          3           0.0a
 Navigational aids                      0           0
 Noise barrier                          0           0
 Planning                               1,659       1.0
 Noise-suppressing equipment            1,000       0.6
 Relocation assistance                  9,178       5.6
 Runway development                     0           0
 Soundproofing                          69,972      42.4
 State grant                            1,113       0.7
 Taxiway development                    0           0
 Fiscal year total                      $164,909    100
 1996
 Land for noise control                 $90,256     47.6
 Landscaping                            528         0.3
 Lighting                               0           0
 Miscellaneous                          15,774      8.3
 Navigational aids                      0           0
 Noise barrier                          1,126       0.6
 Planning                               661         0.3
 Noise-suppressing equipment            167         0.1
 Relocation assistance                  11,737      6.2
 Runway development                     3,250       1.7
 Soundproofing                          63,081      33.3
 State grant                            3,000       1.6
 Taxiway development                    0           0
 Fiscal year total                      $189,580    100
 1997
 Land for noise control                 $60,513     34.7
 Landscaping                            0           0
 Lighting                               1,356       0.8
 Miscellaneous                          9,408       5.4
 Navigational aids                      0           0
 Noise barrier                          602         0.3
 Planning                               1,668       1.0
 Noise-suppressing equipment            2,796       1.6
 Relocation assistance                  9,639       5.5
 Runway development                     7,463       4.3
 Soundproofing                          80,753      46.4
 State grant                            0           0
 Taxiway development                    0           0
 Fiscal year total                      $174,199    100
 1998
 Land for noise control                 $79,355     37.5
 Landscaping                            0           0
 Lighting                               0           0
 Miscellaneous                          97,069      45.9
 Navigational aids                      0           0
 Noise barrier                          0           0
 Planning                               3,352       1.6
 Noise-suppressing equipment            538         0.3
 Relocation assistance                  2,000       0.9
 Runway development                     350         0.2
 Soundproofing                          26,189      12.4
 State grant                            2,855       1.3
 Taxiway development                    0           0
 Fiscal year total                      $211,707    100
 1999
 Land for noise control                 $80,519     33.4
 Landscaping                            0           0
 Lighting                               0           0
 Miscellaneous                          140,340     58.2
 Navigational aids                      0           0
 Noise barrier                          10,411      4.3
 Planning                               2,902       1.2
 Noise-suppressing equipment            906         0.4
 Relocation assistance                  5,700       2.4
 Runway development                     0           0
 Soundproofing                          420         0.2
 State grant                            0           0
 Taxiway development                    0           0
 Fiscal year total                      $241,199    100
 Totals--fiscal years 1982 through 1999
 Land for noise control                 $1,423,579  51.8
 Landscaping                            1,364       0.0a
 Lighting                               6,100       0.2
 Miscellaneous                          280,368     10.2
 Navigational aids                      70          0.0a
 Noise barrier                          21,708      0.8
 Planning                               49,451      1.8
 Noise-suppressing equipment            7,516       0.3
 Relocation assistance                  174,821     6.4
 Runway development                     60,633      2.2
 Soundproofing                          673,020     24.5
 State grant                            18,178      0.7
 Taxiway development                    30,753      1.1
 Grand total                            $2,747,561  100

a The percentage is less than 0.1 percent.

Funding for Noise-Related Projects Through the Passenger Facility Charge
Program, Fiscal Years 1992 Through 1999

Table 12 provides the amount of passenger facility charges approved for
collection for noise-related projects by project type and by fiscal year,
for fiscal years 1992 through 1999. As the table shows, the amount approved
for collection for noise-related projects ranges from a low of $12.8 million
in fiscal year 1995 to a high of $555.0 million in fiscal year 1998.

Table 12: Noise-related Projects Funded Through the Passenger Facility
Charge Program, Fiscal Years 1992 Through 1999, by Project Type

Continued from Previous Page

          Dollars in thousands
      Project type and fiscal year        Amount    Percent
 1992
 Land acquisition                       $142,472    56.8
 Miscellaneous                          192         0.1
 Monitoring                             502         0.2
 Multiphase                             37,306      14.9
 Planning                               732         0.3
 Soundproofing                          69,686      27.8
 Fiscal year total                      $250,890    100
 1993
 Land acquisition                       $44,064     33.9
 Miscellaneous                          612         0.5
 Monitoring                             3,125       2.4
 Multiphase                             2,744       2.1
 Planning                               16          0.0a
 Soundproofing                          79,360      61.1
 Fiscal year total                      $129,921    100
 1994
 Land acquisition                       $39,726     21.2
 Miscellaneous                          0           0
 Monitoring                             465         0.2
 Multiphase                             112,082     59.8
 Planning                               523         0.3
 Soundproofing                          34,609      18.5
 Fiscal year total                      $187,405    100
 1995
 Land acquisition                       $6,779      53.1
 Miscellaneous                          0           0
 Monitoring                             974         7.6
 Multiphase                             0           0
 Planning                               1,447       11.3
 Soundproofing                          3,558       27.9
 Fiscal year total                      $12,758     100
 1996
 Land acquisition                       $61,880     17.5
 Miscellaneous                          6,207       1.8
 Monitoring                             761         0.2
 Multiphase                             99,681      28.2
 Planning                               4,097       1.2
 Soundproofing                          181,091     51.2
 Fiscal year total                      $353,717    100
 1997
 Land acquisition                       $72,300     69.4
 Miscellaneous                          600         0.6
 Monitoring                             1,002       1.0
 Multiphase                             0           0
 Planning                               862         0.8
 Soundproofing                          29,415      28.2
 Fiscal year total                      $104,178    100
 1998
 Land acquisition                       $10,977     2.0
 Miscellaneous                          0           0
 Monitoring                             0           0
 Multiphase                             503,500     90.7
 Planning                               539         0.1
 Soundproofing                          39,964      7.2
 Fiscal year total                      $554,980    100
 1999
 Land acquisition                       $69         0.2
 Miscellaneous                          0           0
 Monitoring                             0           0
 Multiphase                             0           0
 Planning                               10          0.0a
 Soundproofing                          42,986      99.8
 Fiscal year total                      $43,065     100
 Totals--fiscal years 1992 through 1999
 Land acquisition                       $378,267    23.1
 Miscellaneous                          7,611       0.5
 Monitoring                             6,829       0.4
 Multiphase                             755,313     46.1
 Planning                               8,224       0.5
 Soundproofing                          480,669     29.4
 Grand total                            $1,636,913  100

Note: The fiscal year data are based on the year that the airport received
FAA approval to collect passenger facility charges for those kinds of
projects.

aThe percentage is less than 0.1 percent.

Airport Model for Noise Measurement Method Comparisons

We developed an airport model to illustrate and compare the various methods
discussed in the report when applied to a specific airport profile. FAA used
our airport model as the input data to calculate noise levels under the
various measurement methods using its Integrated Noise Model, a computerized
program created to apply most of the noise measurement methods described in
this report. Measurement scenarios were designed to (1) illustrate the kinds
of noise measurements provided by the different methods under the same
airport operations scenario, (2) show the effect on noise contours when
flight schedules are shifted between different times of the day, and (3)
show the effect on noise contours when the total number of aircraft
operations increases from about 26 operations, in increments, to a total of
about 1,586 operations to reflect an airport's growth in activity from very
few operations to a level that reflects the activity of a large commercial
service airport.56

To design our airport model, we selected the single runway pattern of
Manassas Regional Airport in Manassas, Virginia. The number of aircraft
operations for a single day and the distribution of aircraft operations
among the different types of operations--air carrier (commercial service
aircraft with more than 60 seats), air taxi/commuter (commercial service
aircraft with 60 seats or less), and general aviation (all other
aircraft)--was based on the operations levels at the airport that was at the
90th percentile in each of the National Plan of Integrated Airport Systems
airport categories. The 90th percentile was chosen to preclude extreme sizes
but still reflect as closely as possible current operations levels.
According to the operations levels of these airports, (1) the number of
operations for a single day used in the simple comparison of three methods
was
528 operations, distributed equally among each hour of a 24-hour period and
(2) the distribution of aircraft operations in the model was 70-percent air
carrier, 26-percent air taxi/commuter, and 4-percent general aviation.

We selected six aircraft from FAA's list of certificated aircraft to reflect
the distribution of aircraft operations by type of operation--air carrier,
air taxi/commuter, and general aviation. For all aircraft weighing more than
75,000 pounds, stage 3 aircraft were chosen because after December 31, 1999,
large aircraft that do not meet stage 3 requirements were not allowed to
operate at U.S. airports. For aircraft weighing 75,000 pounds or less, both
stage 2 and stage 3 aircraft were selected because both may operate at U.S.
airports. The six aircraft are listed in table 13. FAA conducted the
measurements using its Integrated Noise Model, Version 6.

Table 13: Aircraft Selected for Airport Operations

 Operations category    Aircraft
                        Boeing 747-200

                        4 engine

 Air carrier operations Stage 3

                        Maximum takeoff weight--833,000 pounds

                        Grouping--over 240 seats
                        MD-83

                        2 engine

                        Stage 3

                        Maximum takeoff weight--149,500 pounds

                        Grouping--60 to 170 seats
                        CL-600

                        2 engine

 Air taxi/commuter      Stage 3

                        Maximum takeoff weight--41,250 pounds

                        Grouping--under 60 seats
                        Falcon 20-F

                        2 engine

                        Stage 2

                        Maximum takeoff weight--28,600 pounds

                        Grouping--10 to 40 seats
                        Gulfstream Va

                        Stage 3
 General aviation
                        Maximum takeoff weight--89,000 pounds

                        Grouping--over 75,000 pounds business jet
                        Lockheed 1329-25 Jetstarb

                        4 engine

                        stage 2

                        Maximum takeoff weight--44,500 pounds

                        Grouping--under 75,000 pounds business jet

aThis aircraft is not in FAA's Integrated Noise Model. A Gulfstream IV,
stage 3, with maximum takeoff weight of 71,000 pounds was substituted as the
closest representative of the criteria.

bThis aircraft was not in FAA's Integrated Noise Model. A military C-140,
with 4 engines, stage 2, and a maximum takeoff weight of 44,507 pounds was
substituted. FAA officials said this was the same aircraft but in a military
version.

Comparisons of the Maximum Sound Levels and Sound Exposure Levels for Four
Aircraft

Figures 10 and 11 present the maximum sound level and the sound exposure
level noise measures for four of the six aircraft included in our airport
model. The measures for the remaining two aircraft are presented in chapter
4.

Figure 10: Maximum Sound Level and Sound Exposure Level for the CL 600 and
FAL 20 Aircraft
Figure 11: Maximum Sound Level and Sound Exposure Level for the Gulfstream
IV and MD 83 Aircraft
Stage 3 Aircraft Noise Standards

Figures 12 through 15 show the stage 3 noise standards and the increases in
noise allowed as aircraft weight increases.57 As figures 12 and 13
illustrate, the noise standards for takeoff operations also vary on the
basis of the number of engines. Figure 13 also illustrates how a stage 2
aircraft weighing less than 75,000 pounds could generate less noise than a
heavier aircraft that meets the more stringent stage 3 standards. A lighter
aircraft at point "X" in the figure is a stage 2 aircraft because it
produces noise at a level above the stage 3 standard for aircraft of that
weight, while a heavier aircraft at point "Z" in the figure is a stage 3
aircraft because it produces noise below the stage 3 standard for an
aircraft of that weight. In that case, the stage 2 lighter aircraft is
producing lower noise levels than the heavier aircraft that meets the more
stringent stage 3 standards. By contrast, it is also possible for some types
of smaller aircraft to generate more noise than some types of larger
aircraft. For example, a 1991 FAA study noted that an aircraft weighing
230,000 pounds had a quieter takeoff than 11 types of smaller aircraft
weighing less than 6,500 pounds.58

Figure 12: Noise Standards for Stage 3 Aircraft With Four or More
Engines--Takeoff
Note: The noise measurement level is defined in terms of the "effective
perceived noise level," which takes into account variations in the tone of
noise. The weight scale in the figure is a logarithmic scale.

Figure 13: Noise Standards for Stage 3 Aircraft With Three or Fewer
Engines--Takeoff
Note: The noise measurement level is defined in terms of the "effective
perceived noise level," which takes into account variations in the tone of
noise. The weight scale in the figure is a logarithmic scale.

Figure 14: Noise Standards for Stage 3 Aircraft Regardless of the Number of
Engines--Sideline
Note: The noise measurement level is defined in terms of the "effective
perceived noise level," which takes into account variations in the tone of
noise. The weight scale in the figure is a logarithmic scale.

Figure 15: Noise Standards for Stage 3 Aircraft Regardless of the Number of
Engines--Approach
Note: The noise measurement level is defined in terms of the "effective
perceived noise level," which takes into account variations in the tone of
noise. The weight scale in the figure is a logarithmic scale.

FAA's Compatible Land Use Guidance

Table 14 describes FAA's land use compatibility guidance. In the table,
"Yes" means that the land use and related structures are compatible land
uses. "No" means that the land use and related structures are not compatible
and should be prohibited. The numbers 25, 30, or 35 mean that the land use
and related structures are generally compatible, but measures to achieve a
reduction of 25, 30, or 35 decibels must be incorporated into the design and
construction of the structures. Noise-level reductions refer to the
reduction in noise levels (outdoor to indoor) to be achieved by
incorporating noise attenuation into the design and construction of the
structure.

Table 14: Compatible Land Use Table Based on FAA's Yearly Day-Night Sound
Level Measurements

                                Yearly day-night average sound level in
                                decibels

 Land use                       Below   65-70  70-75  75-80  80-85  Over 85
                                65
 Residential
 Residential, other than mobile
 homes and transient lodgings   Yes     Noa    Noa    No     No     No
 Mobile home parks              Yes     No     No     No     No     No
 Transient lodgings             Yes     Noa    Noa    Noa    No     No
 Public use
 Schools                        Yes     Noa    Noa    No     No     No
 Hospitals                      Yes     25     30     No     No     No
 Churches, auditoriums, and
 concert halls                  Yes     25     30     No     No     No
 Government services            Yes     Yes    25     30     No     No
 Transportation                 Yes     Yes    Yesb   Yesc   Yesd   Yesd
 Parking                        Yes     Yes    Yesb   Yesc   Yesd   No
 Commercial use
 Offices, business and
 professional                   Yes     Yes    25     30     No     No
 Wholesale and retail-building
 materials, hardware and farm   Yes     Yes    Yesb   Yesc   Yesd   No
 equipment
 Retail trade--general          Yes     Yes    25     30     No     No
 Utilities                      Yes     Yes    Yesb   Yesc   Yesd   No
 Communication                  Yes     Yes    25     30     No     No
 Manufacturing and production
 Manufacturing, general         Yes     Yes    Yesb   Yesc   Yesd   No
 Photographic and optical       Yes     Yes    25     30     No     No
 Agriculture (except livestock)
 and forestry                   Yes     Yese   Yesf   Yesg   Yesg   Yesg
 Livestock farming and breeding Yes     Yese   Yesf   No     No     No
 Mining and fishing, resource
 production and extraction      Yes     Yes    Yes    Yes    Yes    Yes
 Recreational
 Outdoor sports arenas and
 spectator sports               Yes     Yesh   Yesh   No     No     No
 Outdoor music shells,
 amphitheaters                  Yes     No     No     No     No     No
 Nature exhibits and zoos       Yes     Yes    No     No     No     No
 Amusements, parks, resorts,
 and camps                      Yes     Yes    Yes    No     No     No
 Golf courses, riding stables
 and water recreation           Yes     Yes    25     30     No     No

aWhere the community determines that residential or school uses must be
allowed, measures to achieve outdoor to indoor reductions of at least 25
decibels should be incorporated into building codes and be considered in
individual approvals. Normal residential construction can be expected to
provide a reduction of 20 decibels; thus, reduction requirements are often
stated as 5, 10, or 15 decibels over standard construction and normally
assume mechanical ventilation and closed windows year round. However, the
use of these criteria will not eliminate outdoor noise problems.

bMeasures to achieve reductions of 25 decibels must be incorporated into the
design and construction of these buildings where the public is received,
office areas, noise sensitive areas or where the normal noise level is low.

cMeasures to achieve reductions of 30 decibels must be incorporated into the
design and construction of these buildings where the public is received,
office areas, noise sensitive areas or where the normal noise level is low.

dMeasures to achieve reductions of 35 decibels must be incorporated into the
design and construction of these buildings where the public is received,
office areas, noise sensitive areas or where the normal noise level is low.

eResidential buildings require reductions of 25 decibels.

fResidential buildings require reductions of 30 decibels.

gResidential buildings not permitted.

hLand use compatible, provided special sound reinforcement systems are
installed.

Advisory Panel Members

John-Paul B. Clarke, Sc.D.
Assistant Professor
Massachusetts Institute of Technology
77 Massachusetts Avenue
Cambridge, Massachusetts 02139-4307

Ms. Carolyn Cunningham, Esq.
Consultant to the Natural Resources Defense Council
18 Soundview Avenue
Rye, New York 10580

Ms. Diane Bryant Gullo
Communications and Noise Abatement Officer
Boca Raton Airport Authority
3700 Airport Road
Suite 304
Boca Raton, Florida 33431

Mr. David A. Hilton
Staff Scientist
Gulfstream Aerospace Corporation
P.O. Box 2206, M/S D-04
Savannah, Georgia 31402-2206

Ms. Nancy S. Timmerman, P.E.
Manager, Noise Monitoring Systems
Massachusetts Port Authority
One Harborside Drive
Suite 200S
East Boston, Massachusetts 02128-2909

GAO Contacts and Staff Acknowledgments

Gerald L. Dillingham (202) 512-2834

Belva Martin (202) 512-2834

In addition to those named above, Beverly Ann Bendekgey, David K. Hooper,
Arthur L. James, Jr., Julian L. King, Carol Herrnstadt Shulman, and John A.
Thomson, Jr. made key contributions to this report.

(348169)

Table 1: Portions of AIP Funds Set Aside for Noise Mitigation
Projects, Fiscal Years 1982 Through 1999 25

Table 2: Typical Sound Levels of Common Occurrences 40

Table 3: Effects of Scheduling Changes on Noise Exposure Levels
Using Three Measurement Methods 49

Table 4: Time-Above Noise Measurements for 60 and 80 A-weighted Decibels 51

Table 5: Short-term Actions Under FAA's Land Use Planning
Initiative 61

Table 6: Summary of Key Land Use Planning Issues Related to
Airport Noise 64

Table 7: Point Values Assigned for Project Purpose in FAA's National
Priority System 75

Table 8: Point Values Assigned for Airport Size in FAA's National
Priority System 75

Table 9: Point Values Assigned for the Component Element in FAA's National
Priority System 76

Table 10: Point Values Assigned for Project Type in FAA's National
Priority System 76

Table 11: Noise-related Projects Funded Through the Airport
Improvement Program, Fiscal Years 1982 Through 1999,
by Project Type 77

Table 12: Noise-related Projects Funded Through the Passenger
Facility Charge Program, Fiscal Years 1992 Through 1999,
by Project Type 86

Table 13: Aircraft Selected for Airport Operations 90

Table 14: Compatible Land Use Table Based on FAA's Yearly
Day-Night Sound Level Measurements 99

Figure 1: Noise Contours at 65 and 60 Decibels for Three
Measurement Methods 14

Figure 2: AIP Noise-Related Projects, Fiscal Years 1982 Through
1999 (Total: $2.7 billion) 35

Figure 3: AIP Noise-Related Projects, Fiscal Years 1982 Through
1999 for Large Airports (Total: $2.1 billion) and for Small
Airports (Total: $582 million) 36

Figure 4: PFC Noise-Related Projects, Fiscal Years 1992 Through
1999 (Total: $1.6 billion) 37

Figure 5: PFC Noise-Related Projects, Fiscal Years 1992 Through
1999 for Large Airports (Total: $1.59 billion) and for Small
Airports (Total: $45.6 million) 38

Figure 6: Single Event Noise Levels Using the Maximum Sound
Level Method and the Sound Exposure Level Method,
Approach and Takeoff--Boeing 747 and C140 Aircraft 44

Figure 7: Noise Contours for Sound Equivalent Level, Day-Night
Sound Level, and Community Noise Equivalent Level Measurement Methods, at
75, 70, 65, 60, and 55 A-weighted Decibels 48

Figure 8: Part 150 Noise Exposure Map Preparation and Acceptance Process 71

Figure 9: Part 150 Noise Compatibility Program Preparation and
Approval Process 73

Figure 10: Maximum Sound Level and Sound Exposure Level for the
CL 600 and FAL 20 Aircraft 91

Figure 11: Maximum Sound Level and Sound Exposure Level for the Gulfstream
IV and MD 83 Aircraft 92

Figure 12: Noise Standards for Stage 3 Aircraft With Four or More
Engines--Takeoff 94

Figure 13: Noise Standards for Stage 3 Aircraft With Three or Fewer
Engines--Takeoff 95

Figure 14: Noise Standards for Stage 3 Aircraft Regardless of the
Number of Engines--Sideline 96

Figure 15: Noise Standards for Stage 3 Aircraft Regardless of the
Number of Engines--Approach 97
  

1. T.J. Schultz, "Synthesis of Social Surveys on Noise Annoyance," Journal
of the Acoustical Society of America 64(2): (1978), pp. 377-405.

2. This report addresses noise issues related to civilian airports only. The
Department of Defense is responsible for noise issues related to military
airports.

3. Sideline noise is measured at points equidistant from both sides of an
aircraft when the aircraft reaches the altitude where sideline noise is at a
maximum.

4. This report addresses noise issues related to civilian airports only. The
Department of Defense has responsibility for noise issues related to
military airports. FAA, the Department of Defense, and other federal
agencies coordinate their noise mitigation efforts through the Federal
Interagency Committee on Noise.

5. FAA is responsible for certifying aircraft as being airworthy, with
regard to noise standards, under regulations in 14 C.F.R. Part 36. Under 49
U.S.C. 44709(b), FAA is specifically authorized to use noise reduction as a
criterion for issuing and revoking certificates relating to the
airworthiness of aircraft. FAA regulates which aircraft may operate at U.S.
airports under regulations in 14 C.F.R. Part 91.

6. The method FAA has chosen for measuring the impact of airport-related
noise on communities places greater weight on noise from flights occurring
between 10 p.m. and
7 a.m.

7. FAA guidance defines certain land uses, such as homes, schools, and
hospitals, as being "incompatible" in areas where the exposure to noise is
65 decibels or higher, as measured in accordance with FAA requirements,
because of the degree to which the noise in those areas interferes with
activities associated with those kinds of uses. FAA's guidance considers all
land uses compatible where the exposure to noise is below 65 decibels when
measured by the method FAA chose in accordance with the statutory
requirement that it select one method for measuring the exposure of
communities to airport-related noise.

8. The Airport and Airway Trust Fund is the repository of revenues collected
from taxes on domestic and international travel, domestic cargo transported
by air, and noncommercial aviation fuel.

9. For noise-related projects funded under the noise "set aside," the
percentages are
20 percent for large airports and 10 percent for small airports.

10. See Passenger Facility Charges: Program Implementation and the Potential
Effects of Proposed Changes (GAO/RCED-99-138 ; May 19, 1999).

11. On April 5, 2000, the President signed the Wendell H. Ford Aviation
Investment and Reform Act (P.L. 106-181), which includes a $1.50 increase in
the maximum fee that may be charged, bringing the maximum fee to $4.50.

12. Thus, PFC funds are not deposited in the U.S. Treasury or subsequently
appropriated.

13. The statute, however, does not require FAA to approve changes in flight
path procedures just because these conditions may be met, even though flight
path procedures are included in the compatibility program. While FAA has
jurisdiction over the approval of changes in flight paths, other criteria
govern the approval of those changes.

14. An airport may prepare and submit to FAA noise exposure maps even though
it does not develop a noise compatibility program.

15. The reimbursement is to be paid to the Secretary of Transportation for
deposit in the Airport and Airway Trust Fund or, as the Secretary
prescribes, reinvested in approved noise compatibility projects. When land
is purchased with AIP grants for other airport purposes and is resold, an
interest in it must also be retained to ensure noise compatible land use.

16. FAA Order 5100.38A, section 710.

17. According to an FAA official, such noise projects are usually
implemented as mitigation of the environmental impacts of other types of
airport development projects and their comparative ranking is based on the
type of development project rather than on the noise project itself.

18. According to an FAA official, most land acquisition projects involve
acquiring homes and relocating the people displaced.

19. This is the first fiscal year of funding for the AIP.

20. The Passenger Facility Charge program was authorized by the Congress in
1990, but approved collections did not begin until fiscal year 1992.

21. Approved collection periods have been as short as 6 months and as long
as 40 years or more.

22. The number of times the waves crest within one second is referred to as
the frequency of the sound, and is expressed in cycles per second, called
hertz. The general range of human hearing is between 20 to 20,000 hertz.
However, the clearest range of human hearing is between 1,000 and 4,000
hertz.

23. A decibel is a unit of sound pressure used to measure noise.

24. An increase of 3 decibels represents a doubling of sound energy, but an
increase of
10 decibels corresponds to the perception by people that the sound level has
doubled.

25. T.J. Schultz, "Synthesis of Social Surveys on Noise Annoyance," Journal
of the Acoustical Society of America 64(2) (1978), pp. 377-405.

26. FAA performed a variety of calculations based on input data we selected
to compare single event and community exposure measurements methods in the
following three contexts:
(1) a single set of measures to illustrate the outputs of the different
methods under the same airport conditions; (2) a series of measures using
changing flight schedules to illustrate the impact of the time of day when
flights occur; and (3) a series of measures using changing numbers of total
aircraft operations to illustrate the impact of the number of takeoffs and
landings. FAA calculated the measurements using its Integrated Noise Model
(Version 6)--FAA's preferred computer model for measuring airport-related
noise when conducting environmental impact or land use compatibility
analyses. App. V describes the airport model.

27. A third method for examining single events, known as the Third Octave
Band Sound Pressure Level method, separates the noise from a single event
into about 30 segments covering the full range of noise generated, including
the low and high frequency sounds that the human ear generally does not hear
as well. Because it covers the full range of sound, this method does not use
A-weighted decibels. However, according to a noise expert,
A-weighted sound levels can be, and often are, computed from one-third
octave band sound levels. FAA's Integrated Noise Model does not produce
measures for this method.

28. Federal Agency Review of Selected Airport Noise Analysis Issues (Federal
Interagency Committee On Noise; Aug. 1992).

29. The operations profile for an average day is based on operations that
occur during a calendar year period.

30. According to FAA officials, the value of the added weight differs for
airport calculations depending on whether it is decibels or "equivalent
number of operations." The State of California, which uses the Community
Noise Equivalent Level method, equates each evening flight to three 3
daytime flights. This results in added weight of 4.77 decibels for each
flight between 7 p.m. and 10 p.m. The Community Noise Equivalent Level
method may also be calculated by applying a 5-decibel penalty, which would
equate each flight to 3.1623 daytime operations. FAA's Integrated Noise
Model uses the approach applied by California.

31. See FAA Brochure entitle Aircraft Noise: How We Measure It and Assess
Its Impact.

32. All three methods produced a similar proportional distribution of land
areas exposed to the various noise levels. The area exposed to noise levels
from 65 to 85 decibels is generally 20 percent or less of the total area
within the 55 to 85 decibel noise exposure range. The portion exposed to 60
to 64 decibels is about 25 percent of the total area, while the portion
exposed to 55 to 59 decibels is generally between 55 percent and 60 percent
of the total area.

33. The following flight schedules were used: (1) all flights in the daytime
(7 a.m. to 7 p.m.),
(2) all flights in the evening (7 p.m. to 10 p.m.), (3) all flights in the
nighttime (10 p.m. to
7 a.m.), (4) half of the flights in the daytime and half in the evening, (5)
half of the flights in the evening and half in the nighttime, (6) half of
the flights in the daytime and half in the nighttime, and (7) half of the
flights during the daytime, one-fourth in the evening, and one-fourth in the
nighttime.

34. Scheduling all flights at night produces the same contours for both the
Day-Night Sound Level method and the Community Noise Equivalent Level method
because there are no flights scheduled during the evening, when the latter
method applies additional weighting to flights.

35. We examined noise measures when total aircraft takeoffs and landings
equaled
26 operations, 78 operations, 234 operations, 468 operations, 702
operations,
1,056 operations, and 1,586 operations. The different levels of total
operations illustrate the impact of the growth in aircraft operations at an
airport, and the differences in noise impacts of airports of different
sizes, holding all other elements constant. Representatives of the Air
Transport Association of America, Inc. noted that if quieter aircraft
replace noisier aircraft, increasing the number of aircraft operations will
not necessarily expand noise contours and may reduce them. The impact of the
quieter aircraft on noise contours will depend, however, on the extent to
which aircraft are replaced, the extent to which operations increase, and
when those operations occur.

36. The size of the geographic areas affected by the Community Noise
Equivalent Level method at each contour level ranged from 3.6 percent to 4.2
percent greater than the areas affected by the Day-Night Sound Level method.

37. 4 C.F.R. section 150.9.

38. The Federal Interagency Committee on Noise, and its successor--the
Federal Interagency Committee on Aviation Noise--include the Departments of
Transportation, Defense, Justice, Veterans Affairs, and Housing and Urban
Development; the Environmental Protection Agency; and the Council on
Environmental Quality.

39. Federal Interagency Review of Selected Airport Noise Analysis Issues
(Federal Interagency Committee on Noise; Aug. 1992).

40. FAA Order 1050.1E. The public comment period closed on Jan. 11, 2000.
Prior to this revision, the order stated only that FAA would consider the
use of supplemental information.

41. These regulations appear in 14 C.F.R. part 36. Sideline noise is
measured at points equidistant from both sides of an aircraft when the
aircraft reaches a certain altitude during takeoff--the altitude where
sideline noise is at a maximum. Aircraft subject to regulation as civil
subsonic turbojets include such aircraft as Boeing 737 and 747, MD-80, and
Gulfstream IV.

42. According to representatives of the Air Transport Association of
America, Inc., there is a tradeoff between reductions in noise and increases
in air emissions because modifications to aircraft to reduce noise often add
to the weight of an aircraft, thereby causing it to burn more fuel.

43. According to an FAA official, many of the organization's member nations,
particularly developing nations, have not yet imposed stage 3 standards on
aircraft.

44. Modifications can include new engines or other modifications such as
hushkits. Hushkits reduce aircraft engine fan and compression noise by
modifying various engine components and by adding acoustic treatment and
noise suppression technology.

45. Amendments to 14 C.F.R. part 36 and part 91 are governed by provisions
of section 611 of the Federal Aviation Act of 1958, as amended.

46. FAA did consider flight operations, however, to be an appropriate
operational noise abatement procedure to further reduce noise where
circumstances warranted.

47. According to the General Aviation Manufacturers Association, this
exception is consistent with guidance adopted by the International Civil
Aviation Organization.

48. As of Oct. 1, 1999, FAA had certified nearly 300,000 fixed-wing aircraft
as airworthy. About 5.3 percent, or just over 15,500, of those were civil
subsonic turbojet aircraft.

49. Study of the Application of Notice and Analysis Requirements to
Operating Noise/Access Restrictions on Subsonic Jets Under 75,000 Pounds,
Federal Aviation Administration, Office of Environment and Energy, June
1991.

50. The statute requires analyses of such things as the costs and benefits
of the proposed restriction and a description of alternatives. The airport
operator also must describe alternative measures considered that do not
involve aircraft restrictions and a comparison of the costs and benefits of
these measures with those that do involve aircraft restrictions. (49 U.S.C.
47524).

51. FAA has issued its designation of compatible and incompatible land uses
in
14 C.F.R. part 150. A summation appears in app. VIII.

52. FAA forecasts a 3.6 percent annual growth in passenger enplanements at
airports between the years 2000 and 2011.

53. FAA requested suggestions and comments from the public in a May 1998
announcement in the Federal Register.

54. According to an FAA official, 7 of the 9 FAA regions generally process
noise exposure maps and noise compatibility programs together, while 2
generally require acceptance of the noise exposure maps before submission of
the noise compatibility program.

55. These are the processes that currently apply to this program. FAA is
preparing revisions, however, to streamline the process and reduce the
implementation costs. FAA officials plan to issue a Notice of Proposed
Rulemaking by the end of the year 2000.

56. We examined noise measures when total aircraft takeoffs and landings
equaled 26, 78, 234, 468, 702, 1,056, and 1,586 operations. The different
levels of operations illustrate the impact of growth in operations at an
airport, and airports of different sizes, when holding all other elements
constant. If aircraft are replaced with quieter aircraft, the impact of the
quieter aircraft on noise contours for an airport will depend on the extent
to which aircraft are replaced, the extent to which operations increase, and
when those operations occur during a 24-hour period.

57. Aircraft must be tested in accordance with the conditions established in
appendix A of
14 C.F.R. part 36. The appendix sets the test requirements for such things
as weather conditions, test procedures, and noise measurement systems to be
used. Appendix B describes how to translate those measurements into a
measure of the "effective perceived noise level," which accounts for the
presence of different tones in sound. The noise standards are established in
appendix C, and they are defined in terms of the effective perceived noise
level.

58. Study of the Application of Notice and Analysis Requirements to
Operating Noise/Access Restrictions on Subsonic Jets Under 75,000 Pounds
(FAA Study Pursuant to Section 9305 of the Airport Noise and Capacity Act of
1990; 1991.)
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