GAO

United States General Accounting Office

Report to Congressional Requesters

April 2000 AVIATION AND THE 

ENVIRONMENT

FAA’s Role in Major 

Airport Noise 

Programs

GAO/RCED-00-98

Page 1 GAO/RCED-00-98 Airport Noise Programs

Contents

Letter 5

Executive Summary 8

Chapter 1

Introduction

20

The Federal Role in Addressing Airport-Related Noise 20

Objectives, Scope, and Methodology 27

Chapter 2

Project Eligibility for 

Federally Authorized 

Funding Is 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

Chapter 3

Noise Measurement 

Methods Provide 

Different Kinds of 

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

Chapter 4

Aircraft Noise 

Standards Vary By 

Aircraft Design and Do 

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
Contents

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Chapter 5

FAA’s Land Use 

Planning Initiative 

Focuses First on 

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

Appendixes 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

Tables 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
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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

Figures 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
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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

Abbreviations

AIP Airport Improvement Program

FAA Federal Aviation Administration

GAO General Accounting Office

PFC Passenger Facility Charge
United States General Accounting Office

Washington, D.C. 20548

Page 5 GAO/RCED-00-98 Airport Noise Programs

Resources, Community, and

Economic Development Division

B-283801 Letr

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
B-283801

Page 6 GAO/RCED-00-98 Airport Noise Programs

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
Page 7 GAO/RCED-00-98 Airport Noise Programs
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Executive Summary

Purpose 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. 
Executive Summary

Page 9 GAO/RCED-00-98 Airport Noise Programs

Background 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, 

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.
Executive Summary

Page 10 GAO/RCED-00-98 Airport Noise Programs

and it requested comments and suggestions from the aviation community 

and the general public.

Results in Brief 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 FAAapproved 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 noiserelated 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. 
Executive Summary

Page 11 GAO/RCED-00-98 Airport Noise Programs

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 airportrelated 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. 
Executive Summary

Page 12 GAO/RCED-00-98 Airport Noise Programs

Principal Findings

Most Types of Noise-Related 

Projects Are Eligible for 

Funding, but 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 
Executive Summary

Page 13 GAO/RCED-00-98 Airport Noise Programs

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 noiserelated projects have been used to acquire land and to soundproof 

buildings. This pattern generally holds true for both large and small 

airports. 

Noise Measurement 

Methods Provide Different 

Kinds of Information

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 
Executive Summary

Page 14 GAO/RCED-00-98 Airport Noise Programs

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.

-10

Miles from runway

-5 0 5 10 15 20

65 decibels

60 decibels

Community noise equivalent level 

Day-night sound level

Equivalent sound level

Aircraft approach Aircraft takeoff
Executive Summary

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Civil Subsonic Turbojet 

Aircraft Noise Standards 

Vary by Aircraft 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. 

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. 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 

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.
Executive Summary

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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?

Agency Comments 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 
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Page 17 GAO/RCED-00-98 Airport Noise Programs

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; 
Executive Summary

Page 18 GAO/RCED-00-98 Airport Noise Programs

(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 tradeoffs 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.
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Chapter 1

Introduction Chapte1r

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 airportrelated 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.1

The Federal Role in 

Addressing AirportRelated Noise

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 aircraftgenerated 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. 

1

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.
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Introduction

Page 21 GAO/RCED-00-98 Airport Noise Programs

Reducing Airport-Related 

Noise at Its Source

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 aircraftgenerated 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.2

 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 

2

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.
Chapter 1

Introduction

Page 22 GAO/RCED-00-98 Airport Noise Programs

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.

Changing an Airport’s Use 

or Operations

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.3

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.

3

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. 
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Introduction

Page 23 GAO/RCED-00-98 Airport Noise Programs

Mitigating the Effects of 

Airport-Related Noise 

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.4

 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 Fund5

—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.6

4

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.

5

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.

6

For noise-related projects funded under the noise “set aside,” the percentages are 

20 percent for large airports and 10 percent for small airports.
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Introduction

Page 24 GAO/RCED-00-98 Airport Noise Programs

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. 
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Introduction

Page 25 GAO/RCED-00-98 Airport Noise Programs

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

1982 Through 1999

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 program7

—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.8

 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.9

 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.

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

7

See Passenger Facility Charges: Program Implementation and the Potential Effects of 

Proposed Changes (GAO/RCED-99-138; May 19, 1999).

8

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.

9

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

Page 26 GAO/RCED-00-98 Airport Noise Programs

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 program10 as long 

as the program 

• does not place an unreasonable burden on interstate or foreign 

commerce, 

• is reasonably consistent with achieving the goal of reducing 

incompatible land uses and preventing the introduction of new 

incompatible land uses, and

• 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 FAAapproved noise compatibility programs, while 212 had approved noise 

exposure maps.11 Appendix I describes the process for obtaining FAA 

approval of the maps and airports’ noise compatibility programs.

10The 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.

11An airport may prepare and submit to FAA noise exposure maps even though it does not 

develop a noise compatibility program.
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Introduction

Page 27 GAO/RCED-00-98 Airport Noise Programs

Objectives, Scope, and 

Methodology

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: 

• 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?

• How do major methods for measuring the impact of airport-related 

noise compare with each other, and what method has FAA selected?

• 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?

• 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-
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Introduction

Page 28 GAO/RCED-00-98 Airport Noise Programs

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. 
Chapter 1

Introduction

Page 29 GAO/RCED-00-98 Airport Noise Programs

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.
Page 30 GAO/RCED-00-98 Airport Noise Programs

Chapter 2

Project Eligibility for Federally Authorized 

Funding Is Broad, but Other Factors Affect 

Project Selection Chapte2r

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. 

Most Types of Projects 

Are Eligible for AIP, but 

They Generally Must 

Be Part of an FAAApproved 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:

• 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;

• an airport will retain a legal interest in the land when it is sold in order 

to ensure that its use remains compatible; and

• the government’s share of the cost of purchasing the land will be 

reimbursed when the land is sold.1

In addition, federal appropriations law prohibits the use of AIP funds for 

studies, maps, or environmental impact analyses needed to implement 

1

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. 
Chapter 2

Project Eligibility for Federally Authorized 

Funding Is Broad, but Other Factors Affect 

Project Selection

Page 31 GAO/RCED-00-98 Airport Noise Programs

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.

Selection Criteria 

Influence Which 

Eligible Projects 

Receive AIP 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.).2

 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 noiserelated projects in the past have been awarded for projects where 

incompatible land uses occur in areas exposed to noise levels of 

2

FAA Order 5100.38A, section 710.
Chapter 2

Project Eligibility for Federally Authorized 

Funding Is Broad, but Other Factors Affect 

Project Selection

Page 32 GAO/RCED-00-98 Airport Noise Programs

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: 

• 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; 

• 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;

• 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 

• 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. 
Chapter 2

Project Eligibility for Federally Authorized 

Funding Is Broad, but Other Factors Affect 

Project Selection

Page 33 GAO/RCED-00-98 Airport Noise Programs

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.3

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.

The PFC Program Can 

Fund Some Project 

Costs Ineligible for AIP 

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 

3

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.
Chapter 2

Project Eligibility for Federally Authorized 

Funding Is Broad, but Other Factors Affect 

Project Selection

Page 34 GAO/RCED-00-98 Airport Noise Programs

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.

Land Acquisition and 

Soundproofing 

Projects Receive the 

Majority of 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.4

 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. 

AIP Projects Of the nearly $24 billion in AIP grants awarded for fiscal years 19825

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.

4

According to an FAA official, most land acquisition projects involve acquiring homes and 

relocating the people displaced.

5

This is the first fiscal year of funding for the AIP.
Chapter 2

Project Eligibility for Federally Authorized 

Funding Is Broad, but Other Factors Affect 

Project Selection

Page 35 GAO/RCED-00-98 Airport Noise Programs

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 noiserelated projects. As figure 3 shows, both large and small airports targeted 

their AIP grants for land acquisition and soundproofing buildings.

Land acquisition 

$1,423.6

Other 

$195.8 

Relocation assistance

$174.8

Miscellaneous

$280.4

Soundproofing

$673.0

Runway development 2.2%

Planning 1.8%

Taxiway development 1.1%

Noise barrier 0.8%

Noise suppression equipment 0.3%

Lighting 0.2%

Landscaping 0.1%

State grant 0.7%

Total 7.2%

Dollars in millions

51.8%

 24.5%

10.2%

6.4%

7.2%
Chapter 2

Project Eligibility for Federally Authorized 

Funding Is Broad, but Other Factors Affect 

Project Selection

Page 36 GAO/RCED-00-98 Airport Noise Programs

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.

PFC Projects For fiscal years 19926

 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.7

 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 

Soundproofing 

$598.0 Land acquisition

$1,130.0

Dollars in millions 

Large airports

Miscellaneous

$217.6

Relocation assistance

$138.7

Other 

2.9% $62.8

6.5%

10.1%

27.9%

52.6%

Soundproofing 

$75.1 Land acquisition

$293.6

Dollars in millions

Small airports

Miscellaneous

$62.8

Relocation assistance

$36.1

Other 

19.7% $114.8

6.2%

10.8%

12.9%

50.4%

6

The Passenger Facility Charge program was authorized by the Congress in 1990, but 

approved collections did not begin until fiscal year 1992.

7

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

more.
Chapter 2

Project Eligibility for Federally Authorized 

Funding Is Broad, but Other Factors Affect 

Project Selection

Page 37 GAO/RCED-00-98 Airport Noise Programs

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 multiplephase 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.

Soundproofing 

$480.7

Multiphase funding

$755.3

Dollars in millions

Land acquisition

$378.3

Other 1.4% 

$22.7

23.1%

29.4%

46.1%

Miscellaneous 0.5%

Noise monitoring equipment 0.4%

Planning 0.5%

Total 1.4%
Chapter 2

Project Eligibility for Federally Authorized 

Funding Is Broad, but Other Factors Affect 

Project Selection

Page 38 GAO/RCED-00-98 Airport Noise Programs

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.

a

Percentages do not total 100 percent because of rounding.

Soundproofing 

$478.7

Multiphase 

funding

$734.8

Dollars in millions Dollars in millions

Large airportsa

Land acquisition

$355.8

Other 1.4% 

$22.0

22.4%

30.1%

46.2%

Soundproofing 

$1.9

Land acquisition

$22.5

Other 1.4%

$0.6

49.3%

4.3%

Multiphase 

funding

$20.6

Small airports

45.0%
Page 39 GAO/RCED-00-98 Airport Noise Programs

Chapter 3

Noise Measurement Methods Provide 

Different Kinds of Information Chapte3r

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.

Measuring Sound and 

Its Effects

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.1

 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.2

 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.3

 Continuing the increase from 60 to 70 decibels would again 

1

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.

2

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

3

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.
Chapter 3

Noise Measurement Methods Provide 

Different Kinds of Information

Page 40 GAO/RCED-00-98 Airport Noise Programs

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

Source: Federal Interagency Review of Selected Airport Noise Analysis Issues (Federal Interagency 

Committee on Noise; August 1992).

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
Chapter 3

Noise Measurement Methods Provide 

Different Kinds of Information

Page 41 GAO/RCED-00-98 Airport Noise Programs

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.4

 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. 

Measures of Noise 

Identify Noise Levels of 

Single Aircraft 

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.

Single Event Measures 

Provide Short-term 

Information

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.

4

T.J. Schultz, “Synthesis of Social Surveys on Noise Annoyance,” Journal of the Acoustical 

Society of America 64(2) (1978), pp. 377-405.
Chapter 3

Noise Measurement Methods Provide 

Different Kinds of Information

Page 42 GAO/RCED-00-98 Airport Noise Programs

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. 
Chapter 3

Noise Measurement Methods Provide 

Different Kinds of Information

Page 43 GAO/RCED-00-98 Airport Noise Programs

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.5

 

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.6

5

 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.

6

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.
Chapter 3

Noise Measurement Methods Provide 

Different Kinds of Information

Page 44 GAO/RCED-00-98 Airport Noise Programs

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.7

 Thus, by 

themselves, methods to measure the noise from single events are not 

considered to describe the overall noise environment.

0

20

40

60

80

100

120

Aircraft:

Miles from runway

A-weighted decibel

C140 Sound exposure level

747 maximum sound level

C140 maximum sound level

747 Sound exposure level

Aircraft approach Aircraft takeoff

-35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35
Chapter 3

Noise Measurement Methods Provide 

Different Kinds of Information

Page 45 GAO/RCED-00-98 Airport Noise Programs

Noise in Communities Is 

Measured in Terms of 

Overall Exposure 

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,8

 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, 

7

Federal Agency Review of Selected Airport Noise Analysis Issues (Federal Interagency 

Committee On Noise; Aug. 1992).

8

The operations profile for an average day is based on operations that occur during a 

calendar year period.
Chapter 3

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Different Kinds of Information

Page 46 GAO/RCED-00-98 Airport Noise Programs

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.9

 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: 

9

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.
Chapter 3

Noise Measurement Methods Provide 

Different Kinds of Information

Page 47 GAO/RCED-00-98 Airport Noise Programs

• 500 aircraft operations with an average sound exposure level of 

87.4 decibels;

• 100 aircraft operations with an average sound exposure level of 

94.4 decibels; and

• 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.10

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 2-1⁄2 times as large to 3-1⁄2 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.11

10See FAA Brochure entitle Aircraft Noise: How We Measure It and Assess Its Impact.

11All 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.
Chapter 3

Noise Measurement Methods Provide 

Different Kinds of Information

Page 48 GAO/RCED-00-98 Airport Noise Programs

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.

-15

Miles from runway

-10 -5 0 5 10 15 20 25 30

55 decibels

70 decibels

65 decibels

75 decibels

60 decibels

Aircraft approach Aircraft takeoff

Community noise equivalent level 

Day-night sound level

Equivalent sound level
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Page 49 GAO/RCED-00-98 Airport Noise Programs

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.12 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.13 Table 3 illustrates the impact of 

changing flight schedules.

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

a

When all flights occurred during the day, all three methods produced the exact same size areas 

exposed to the various noise levels.

12The 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 onefourth in the nighttime. 

13Scheduling 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.

Flight Schedule

Method All daytime flights All evening flights All nighttime flights

Equivalent Sound Level Areas exposed to noisea

 No change No change

Day-Night Sound Level Areas exposed to noisea No change More than quadrupled size of 

areas

Community Noise Equivalent Areas exposed to noisea

 Doubled size of areas exposed 

to noise

More than quadrupled size of 

areas
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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.14 

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 greater15 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.

14We 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.

15The 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.
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Page 51 GAO/RCED-00-98 Airport Noise Programs

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

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. 

Minutes per day 

above noise level—takeoff 

Minutes per day 

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
Chapter 3

Noise Measurement Methods Provide 

Different Kinds of Information

Page 52 GAO/RCED-00-98 Airport Noise Programs

FAA Selected the DayNight Sound Level 

Method for Measuring 

Noise 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.16

In 1992, the Federal Interagency Committee on Noise noted that the DayNight Sound Level method was practical and widely accepted.17 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.18 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 

164 C.F.R. section 150.9.

17The 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.

18Federal Interagency Review of Selected Airport Noise Analysis Issues (Federal 

Interagency Committee on Noise; Aug. 1992).
Chapter 3

Noise Measurement Methods Provide 

Different Kinds of Information

Page 53 GAO/RCED-00-98 Airport Noise Programs

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 DayNight 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.19 The revision adds new guidance on the kinds of supplemental 

information available and their use.

19FAA 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.
Page 54 GAO/RCED-00-98 Airport Noise Programs

Chapter 4

Aircraft Noise Standards Vary By Aircraft 

Design and Do Not Apply to Some Lighter 

Aircraft Chapte4r

FAA establishes the standards limiting the noise that civil subsonic turbojet 

aircraft are permitted to generate.1

 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 Standards 

Generally Permit 

Heavier Aircraft to 

Generate More 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.2

 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.

1

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.

2

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.
Chapter 4

Aircraft Noise Standards Vary By Aircraft 

Design and Do Not Apply to Some Lighter 

Aircraft

Page 55 GAO/RCED-00-98 Airport Noise Programs

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.3

The European Union has banned, after May 1, 2000, stage 2 aircraft that 

were modified to meet stage 3 noise standards,4

 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.

Existing Aircraft 

Weighing 75,000 

Pounds or Less Have 

Been Exempt 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 

3

According to an FAA official, many of the organization’s member nations, particularly 

developing nations, have not yet imposed stage 3 standards on aircraft. 

4

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.
Chapter 4

Aircraft Noise Standards Vary By Aircraft 

Design and Do Not Apply to Some Lighter 

Aircraft

Page 56 GAO/RCED-00-98 Airport Noise Programs

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. 

Exemption From the Stage 1 

Operating Deadline Was for 

Technological 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.5

 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.

5

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.
Chapter 4

Aircraft Noise Standards Vary By Aircraft 

Design and Do Not Apply to Some Lighter 

Aircraft

Page 57 GAO/RCED-00-98 Airport Noise Programs

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 costeffectiveness 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.6

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.

6

FAA did consider flight operations, however, to be an appropriate operational noise 

abatement procedure to further reduce noise where circumstances warranted.
Chapter 4

Aircraft Noise Standards Vary By Aircraft 

Design and Do Not Apply to Some Lighter 

Aircraft

Page 58 GAO/RCED-00-98 Airport Noise Programs

Statutory Deadline for 

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.7

 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.8

 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.9

 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.10 Unlike noise or access restrictions proposed for 

stage 3 aircraft, FAA approval is not required.

7

According to the General Aviation Manufacturers Association, this exception is consistent 

with guidance adopted by the International Civil Aviation Organization.

8

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.

9

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.

10The 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).
Page 59 GAO/RCED-00-98 Airport Noise Programs

Chapter 5

FAA’s Land Use Planning Initiative Focuses 

First on Improving Access to Information Chapte5r

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.

FAA Facilitates State 

and Local Land Use 

Planning Efforts

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.1

 Although FAA can provide land use planning 

guidance, it is up to the state and to local communities to apply this 

guidance.

1

FAA has issued its designation of compatible and incompatible land uses in 

14 C.F.R. part 150. A summation appears in app. VIII.
Chapter 5

FAA’s Land Use Planning Initiative Focuses 

First on Improving Access to Information

Page 60 GAO/RCED-00-98 Airport Noise Programs

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.2

 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.

Short-Term Actions 

Aim at Improving the 

Communication of 

Information

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.

2

FAA forecasts a 3.6 percent annual growth in passenger enplanements at airports between 

the years 2000 and 2011.
Chapter 5

FAA’s Land Use Planning Initiative Focuses 

First on Improving Access to Information

Page 61 GAO/RCED-00-98 Airport Noise Programs

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

a

The 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.

b

This 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 

Action Responsible FAA office Implementation status

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 transition to quieter aircraft; testimony on noise issues and 

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.

Office of Environment and 

Energy

Implementation goal--

March 31, 2000a

Develop an information package on existing statutes for state aviation 

organizations through the National Association of State Aviation Officials.b

Office of Environment and 

Energy

Implementation goal--

March 31, 2000a

Provide an information clearinghouse—readily accessible to federal, state, 

local, industry and public users—for compatible land use planning 

information, including FAA orders, advisory circulars, reports, studies, and 

other related information; and access to available land use planning 

resources that are applicable to aviation.

Office of Airport Planning and 

Programming

An Internet website was 

created, enabling the 

agency to meet the original 

implementation goal of 

September 30, 1999.

Use a rapid-response procedure within the agency to respond quickly to 

inquiries on FAA policies. This procedure would include a mechanism to 

assist airports, jurisdictions, and/or communities attempting to resolve 

conflicts between airport and community needs.

Office of Environment and 

Energy

Implementation goal--

March 31, 2000a

Provide clearer understanding of what FAA might do to address noise 

exposure, particularly in relation to areas exposed to noise levels below the 

65 decibel level--the level at which all land uses are currently considered 

compatible--and in areas outside the airport’s direct control. FAA actions 

include providing greater FAA focus on the use of in-flight procedures to 

achieve noise abatement, and more consultations with airports and 

communities in those lower exposure areas.

Office of Environment and 

Energy

FAA revised its order in 

June 1999 that provides 

guidance on environmental 

impact analyses concerning 

airports, enabling the 

agency to meet the original 

implementation goal of 

September 30, 1999.
Chapter 5

FAA’s Land Use Planning Initiative Focuses 

First on Improving Access to Information

Page 62 GAO/RCED-00-98 Airport Noise Programs

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.
Chapter 5

FAA’s Land Use Planning Initiative Focuses 

First on Improving Access to Information

Page 63 GAO/RCED-00-98 Airport Noise Programs

Initiative Raises Key Issues 

in Noise Mitigation Efforts

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.3

 Table 6 summarizes the context and scope of these issues.

3

FAA requested suggestions and comments from the public in a May 1998 announcement in 

the Federal Register.
Chapter 5

FAA’s Land Use Planning Initiative Focuses 

First on Improving Access to Information

Page 64 GAO/RCED-00-98 Airport Noise Programs

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

Issue Context of issue Scope of issue

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?

FAA has no direct jurisdiction 

over land use or zoning 

decision-making. Zoning 

authority is the province of 

state and local governments.

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 focus on those activities over which 

it has authority, such as changing flight paths or mandating new 

aircraft noise reductions.

FAA officials believe that land use planning is an 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.

Should the noise level defining 

all land uses as compatible be 

lowered or retained at the 

65 decibel Day-Night Sound 

Level measure?

FAA’s regulations establish a 

noise exposure level below 

which all land uses are 

considered compatible with 

airport-related noise and 

above which residential and 

certain other development is 

considered incompatible with 

that noise. FAA uses that 

level to help set priorities for 

funding decisions for noise 

abatement projects, resulting 

in few projects being 

approved where all land 

uses are compatible under 

federal guidelines.

Some interested parties, particularly community and environmental 

groups as well as individuals, believe that the noise exposure level 

below which all land uses are compatible is too high and should be 

lowered. This is also a particular concern because that level has a 

very strong influence on FAA’s decisions about which noise 

abatement efforts to fund. 

An FAA official noted that there are not enough federally authorized 

funds to pay for all planned or approved noise mitigation efforts so 

FAA uses the compatible land use noise exposure level to help 

focus funds in the most noise-impacted areas. The official noted 

that FAA does approve the funding of projects where the noise 

exposure level is lower, when warranted, but that very few have 

been approved. 
Chapter 5

FAA’s Land Use Planning Initiative Focuses 

First on Improving Access to Information

Page 65 GAO/RCED-00-98 Airport Noise Programs

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).

Observations 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. 

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?

The law requires FAA to 

establish a single method for 

measuring the noise 

exposure levels in 

communities surrounding 

airports. At their discretion, 

federal agencies provide or 

use supplemental 

information in implementing 

their programs that involve 

assessing noise exposure 

levels.

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 additional 

information be available and be used in assessing the noise 

exposure levels in communities for federal funding and land use 

compatibility determinations.

FAA is required by law to select one measurement of community 

noise exposure. The Federal Interagency Committee on Noise 

noted in a 1992 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. 

How should federally 

authorized investment in 

airport capacity growth be 

directed, given the noise and 

physical expansion constraints 

facing so many of the nation’s 

large airports?

FAA approves federally 

authorized funding for 

projects to expand airport 

capacity. Forecast growth in 

the demand for air travel is 

pressuring airports to 

expand capacity to meet that 

future demand.

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 should direct airport expansion funds to existing 

or new airports that are not affected by noise or geographic 

constraints. 

Proposals for airport expansion originate at the local level. Private 

sector decisions, such as an 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

Issue Context of issue Scope of issue
Chapter 5

FAA’s Land Use Planning Initiative Focuses 

First on Improving Access to Information

Page 66 GAO/RCED-00-98 Airport Noise Programs

Agency Comments 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 InternationalNorth 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 
Chapter 5

FAA’s Land Use Planning Initiative Focuses 

First on Improving Access to Information

Page 67 GAO/RCED-00-98 Airport Noise Programs

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 
Chapter 5

FAA’s Land Use Planning Initiative Focuses 

First on Improving Access to Information

Page 68 GAO/RCED-00-98 Airport Noise Programs

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.
Page 69 GAO/RCED-00-98 Airport Noise Programs
Page 70 GAO/RCED-00-98 Airport Noise Programs

Appendix I

Process for Participating in the Part 150 Noise Apendxies

Compatibility Program ApendxiI

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.
Appendix I

Process for Participating in the Part 150 

Noise Compatibility Program

Page 71 GAO/RCED-00-98 Airport Noise Programs

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.

Airport prepares two noise exposure maps 

Current operations map—identifies current noise contours and incompatible land uses at existing aircraft operating levels

Future operations map—identifies aircraft operations and incompatible land uses at projected noise levels 5 years or 

more into the future

Airport consults with federal, state, and local agencies, public planning agencies, airport users, communities (FAA requires 

consultation with parties within the 65, 70, and 75 noise contour levels), and other interested parties participating in the 

development of the noise exposure maps. The airport also prepares documentation that these agencies, groups, and 

interested parties participated in developing the noise exposure maps.

Airport submits noise exposure maps

Do the maps meet

FAA’s requirements?

Return to airport

for revision

FAA issues notice of

compliance in Federal Register

No

Yes

Airport affirms the correctness and adequacy of noise exposure maps and includes any 

public reviews and written comments that were submitted on each map.

•

•
Appendix I

Process for Participating in the Part 150 

Noise Compatibility Program

Page 72 GAO/RCED-00-98 Airport Noise Programs

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.1

 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. 2

1

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. 

2

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.
Appendix I

Process for Participating in the Part 150 

Noise Compatibility Program

Page 73 GAO/RCED-00-98 Airport Noise Programs

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

a

An airport may submit its noise exposure maps along with the noise compatibility program. 

Airport prepares noise compatibility program, which includes:

Noise exposure mapsa

Description and analysis of alternative noise measures

Proposed program measures to reduce or prevent incompatible land uses

Description of public participation and consultation with federal, state, and local governments and other officials having land-use responsibility

A summary of actual or anticipated effects of the program

A summary of comments and documents submitted to the airport during any public hearing

Data on program implementation schedule, responsible persons, documentation supporting the feasibility of implementation, 

costs, and anticipated sources of funding that will show the funding is consistent with achieving the program's goals

Provisions for revising the program if made necessary by revision of the noise exposure map

•

•

•

•

•

•

Airport consults with federal, state, and local agencies; public planning agencies; airport users; communities; and other interested

parties participating in the development of the noise compatibility program. The airport also prepares documentation showing 

that these agencies, groups, and interested parties participated in developing the noise compatibility program.b

Airport prepares documentation describing the correctness and adequacy of the noise compatibility program and provides any 

public reviews and comments that were submitted at any public hearing on the program.

Airport submits noise compatibility program

Hold until a determination

is made on the map 

No

No

Yes

Does airport have 

a compliant noise

exposure map? 

Does the program

meet FAA’s preliminary

requirements?

FAA publishes a notice of receipt for comment in the 

Federal Register for review and additional public comments 

Return to airport for revision in 

accordance with FAA’s preliminary

review comments

Yes

180-day

approval

periodc FAA evaluates the program

FAA publishes a notice of approval/disapproval in the Federal Register

•

•
Appendix I

Process for Participating in the Part 150 

Noise Compatibility Program

Page 74 GAO/RCED-00-98 Airport Noise Programs

b

FAA’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.

c

Flight 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.
Page 75 GAO/RCED-00-98 Airport Noise Programs

Appendix II

National Priority System for AIP-Eligible 

Projects ApendxiI

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

Table 8: Point Values Assigned for Airport Size 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.

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

2 Other commercial service and general aviation airports with less than 

20 based aircraft or less than 8,000 operations
Appendix II

National Priority System for AIP-Eligible 

Projects

Page 76 GAO/RCED-00-98 Airport Noise Programs

Table 9: Point Values Assigned for the Component Element in FAA’s National 

Priority System

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

Points Type of component

10 Runway

9 Helipad, seaplane

8 Equipment, taxiway

7 Homes—residential noise mitigation; land; other, such as fuel 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

Points Category of type

10 Noise projects in 75-decibel day-night sound level and above, construction, 

obstruction removal, aircraft rescue fire fighting vehicle

9 Runway friction, master planning, runway/taxiway signs, snow removal 

equipment

8 Improvement to existing infrastructure, lighting, runway safety area, 

sensors, state planning, safety zone, visual approach aid, weather reporting 

equipment

7 Noise projects in 70- to 74-decibel day-night sound level, 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
Page 77 GAO/RCED-00-98 Airport Noise Programs

Appendix III

Funding for Noise-Related Projects Through 

the Airport Improvement Program, Fiscal 

Years 1982 Through 1999 ApendxiI

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

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

Continued
Appendix III

Funding for Noise-Related Projects Through 

the Airport Improvement Program, Fiscal 

Years 1982 Through 1999

Page 78 GAO/RCED-00-98 Airport Noise Programs

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

Dollar in thousands

Project type and fiscal year Amount Percent

Continued from Previous Page
Appendix III

Funding for Noise-Related Projects Through 

the Airport Improvement Program, Fiscal 

Years 1982 Through 1999

Page 79 GAO/RCED-00-98 Airport Noise Programs

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

Dollar in thousands

Project type and fiscal year Amount Percent

Continued from Previous Page
Appendix III

Funding for Noise-Related Projects Through 

the Airport Improvement Program, Fiscal 

Years 1982 Through 1999

Page 80 GAO/RCED-00-98 Airport Noise Programs

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

Dollar in thousands

Project type and fiscal year Amount Percent

Continued from Previous Page
Appendix III

Funding for Noise-Related Projects Through 

the Airport Improvement Program, Fiscal 

Years 1982 Through 1999

Page 81 GAO/RCED-00-98 Airport Noise Programs

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

Dollar in thousands

Project type and fiscal year Amount Percent

Continued from Previous Page
Appendix III

Funding for Noise-Related Projects Through 

the Airport Improvement Program, Fiscal 

Years 1982 Through 1999

Page 82 GAO/RCED-00-98 Airport Noise Programs

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

Dollar in thousands

Project type and fiscal year Amount Percent

Continued from Previous Page
Appendix III

Funding for Noise-Related Projects Through 

the Airport Improvement Program, Fiscal 

Years 1982 Through 1999

Page 83 GAO/RCED-00-98 Airport Noise Programs

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

Dollar in thousands

Project type and fiscal year Amount Percent

Continued from Previous Page
Appendix III

Funding for Noise-Related Projects Through 

the Airport Improvement Program, Fiscal 

Years 1982 Through 1999

Page 84 GAO/RCED-00-98 Airport Noise Programs

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

Dollar in thousands

Project type and fiscal year Amount Percent

Continued from Previous Page
Appendix III

Funding for Noise-Related Projects Through 

the Airport Improvement Program, Fiscal 

Years 1982 Through 1999

Page 85 GAO/RCED-00-98 Airport Noise Programs

a

The percentage is less than 0.1 percent.

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

Dollar in thousands

Project type and fiscal year Amount Percent

Continued from Previous Page
Page 86 GAO/RCED-00-98 Airport Noise Programs

Appendix IV

Funding for Noise-Related Projects Through 

the Passenger Facility Charge Program, Fiscal 

Years 1992 Through 1999 ApendxiIV

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

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

Continued
Appendix IV

Funding for Noise-Related Projects Through 

the Passenger Facility Charge Program, 

Fiscal Years 1992 Through 1999

Page 87 GAO/RCED-00-98 Airport Noise Programs

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

Dollars in thousands

Project type and fiscal year Amount Percent

Continued from Previous Page
Appendix IV

Funding for Noise-Related Projects Through 

the Passenger Facility Charge Program, 

Fiscal Years 1992 Through 1999

Page 88 GAO/RCED-00-98 Airport Noise Programs

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.

a

The percentage is less than 0.1 percent.

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

Dollars in thousands

Project type and fiscal year Amount Percent

Continued from Previous Page
Page 89 GAO/RCED-00-98 Airport Noise Programs

Appendix V

Airport Model for Noise Measurement Method 

Comparisons ApendxiV

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.1

The Airport Model 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 

1

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.
Appendix V

Airport Model for Noise Measurement 

Method Comparisons

Page 90 GAO/RCED-00-98 Airport Noise Programs

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

a

This 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.

b

This 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.

Operations category Aircraft

Air carrier operations Boeing 747-200

4 engine

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

Air taxi/commuter CL-600

2 engine

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

General aviation Gulfstream Va

Stage 3

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
Page 91 GAO/RCED-00-98 Airport Noise Programs

Appendix VI

Comparisons of the Maximum Sound Levels 

and Sound Exposure Levels for Four Aircraft ApendxiVI

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

Miles from runway

Aircraft:

A-weighted decibel

0

20

40

60

80

100

120

FAL20 sound exposure level

CL600 sound exposure level

FAL20 maximum sound level

CL600 maximum sound level

Aircraft approach Aircraft takeoff

-35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35
Appendix VI

Comparisons of the Maximum Sound Levels 

and Sound Exposure Levels for Four Aircraft

Page 92 GAO/RCED-00-98 Airport Noise Programs

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

Miles from runway

Aircraft:

A-weighted decibel

20

40

60

80

100

120

MD83 sound exposure level MD83 maximum sound level

GIV sound exposure level GIV maximum sound level

Aircraft approach Aircraft takeoff

-35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35
Page 93 GAO/RCED-00-98 Airport Noise Programs

Appendix VII

Stage 3 Aircraft Noise Standards ApendxiVI

Figures 12 through 15 show the stage 3 noise standards and the increases in 

noise allowed as aircraft weight increases.1

 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.2

1

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.

2

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.)
Appendix VII

Stage 3 Aircraft Noise Standards

Page 94 GAO/RCED-00-98 Airport Noise Programs

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.

88

90

92

94

96

98

100

102

104

106

108

10,000

100,000

1,000,000

106,250

212,500

425,000

850,000

44,673

53,125

Aircraft weight in pounds

Noise measurement level
Appendix VII

Stage 3 Aircraft Noise Standards

Page 95 GAO/RCED-00-98 Airport Noise Programs

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.

88

90

92

94

96

98

100

102

104

106

10,000

100,000

1,000,000

106,250

212,500

425,000

850,000

63,177

Aircraft weight in pounds

Noise measurement level

3 engines - takeoff 2 engines or less - takeoff

X

Z
Appendix VII

Stage 3 Aircraft Noise Standards

Page 96 GAO/RCED-00-98 Airport Noise Programs

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.

10,000

100,000

1,000,000

110,250

220,500

441,000

882,000

77,200

Aircraft weight in pounds

Noise measurement level

88

90

92

94

96

98

100

102

104
Appendix VII

Stage 3 Aircraft Noise Standards

Page 97 GAO/RCED-00-98 Airport Noise Programs

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.

10,000

100,000

1,000,000

77,200

154,325

308,650

617,300

Aircraft weight in pounds

Noise measurement level

88

90

92

94

96

98

100

102

104

106
Page 98 GAO/RCED-00-98 Airport Noise Programs

Appendix VIII

FAA’s Compatible Land Use Guidance ApendxiVI

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.
Appendix VIII

FAA’s Compatible Land Use Guidance

Page 99 GAO/RCED-00-98 Airport Noise Programs

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

a

Where 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.

Yearly day-night average sound level in decibels

Land use Below 65 65-70 70-75 75-80 80-85 Over 85

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 

equipment

Yes Yes Yesb Yesc Yesd No

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
Appendix VIII

FAA’s Compatible Land Use Guidance

Page 100 GAO/RCED-00-98 Airport Noise Programs

b

Measures 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.

c

Measures 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.

d

Measures 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.

e

Residential buildings require reductions of 25 decibels.

f

Residential buildings require reductions of 30 decibels.

g

Residential buildings not permitted.

h

Land use compatible, provided special sound reinforcement systems are installed.
Page 101 GAO/RCED-00-98 Airport Noise Programs

Appendix IX

Advisory Panel Members ApendxiIX

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
Page 102 GAO/RCED-00-98 Airport Noise Programs

Appendix X

GAO Contacts and Staff Acknowledgments ApendxiX

GAO Contacts Gerald L. Dillingham (202) 512-2834

Belva Martin (202) 512-2834

Staff 

Acknowledgments

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.

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