AIRPORT NOISE 

GRANTS

FAA Needs to Better 

Ensure Project 

Eligibility and 

Improve Strategic 

Goal and Performance 

Measures

Report to the Committee on Commerce, 

Science, and Transportation, 

U.S. Senate

September 2012

GAO-12-890

United States Government Accountability Office

GAO
United States Government Accountability Office

Highlights of GAO-12-890, a report to

Committee on Commerce, Science, and 

Transportation, U.S. Senate

September 2012

AIRPORT NOISE GRANTS

FAA Needs to Better Ensure Project Eligibility and 

Improve Strategic Goal and Performance Measures

Why GAO Did This Study

The Federal Aviation Administration 

(FAA) predicts that air traffic in the 

United States will increase 20 percent 

by 2024. If not mitigated, the noise

associated with these flights could

significantly diminish the quality of life 

for communities surrounding airports

and constrain an airport’s ability to 

expand. Over the last 30 years, 

Congress has provided billions of 

dollars in grants under the Airport 

Improvement Program to airports to 

reduce and mitigate significant noise 

exposure. FAA’s overall strategic noise

goal is to reduce the population 

exposed to significant noise to fewer

than 300,000 people nationwide. 

At your request, GAO (1) described 

how airport noise exposure has 

changed, (2) evaluated noise grant 

results, and (3) assessed potential 

future demand for these grants. GAO

analyzed FAA data on noise grants, 

planned projects, and population 

exposure and reviewed relevant 

literature. GAO also conducted 

interviews with relevant airport and 

FAA officials and industry 

representatives, as well as visited

seven airports that have used noise 

grants, judgmentally selected based on 

size, location, and other factors. 

What GAO Recommends

GAO recommends that the Department 

of Transportation align its strategic 

goal for noise reduction with the results 

of the noise grant program and

establish corresponding performance 

measures. The department provided 

technical comments and agreed to 

consider the recommendations.

What GAO Found

The number of people in the United States exposed to significant airport noise

has steadily declined from roughly 7 million people in 1975 to about 309,000 

today. This change reflects large decreases in the size of areas that are exposed 

to significant airport noise and is primarily due to improvements in aircraft 

technology. 

Since 1982, FAA has provided $5.8 billion in Airport Improvement Program noise 

grants to 481 airports for residential and public building noise insulation and land 

acquisition, among other project types. The majority of grants went to airports 

that voluntarily undertook Noise Compatibility Programs (NCP). While these 

funds benefitted thousands of people, GAO identified two areas of concern 

regarding FAA’s enforcement of project eligibility criteria that creates a risk that 

some undetermined amount of grant funds may have gone to projects that do not 

meet FAA’s project eligibility criteria. First, FAA does not always require airports

to maintain updated and accurate noise exposure maps to define eligible project 

areas. For example, half of the noise exposure maps—which show the areas 

around an airport that are exposed to significant airport noise and are a key 

element in determining project eligibility—are from the 1990s or earlier. For an 

airport to receive a noise grant, program criteria generally require that such maps 

are updated every 5 years, but nine airports received $87.6 million in grants in 

fiscal years 2010 to 2011 based on maps that predate 2000. Second, FAA has 

inconsistently implemented requirements that limit residential noise insulation

projects to homes with interior noise levels above an established threshold. In the 

absence of FAA enforcement, airports have little incentive to update maps and 

limit residential treatment because doing so might eliminate planned projects 

expected by the public. Concurrent to GAO’s review, FAA issued new guidance 

that should substantially address this risk if effectively implemented. Further, the 

results of noise grants are not linked to FAA’s strategic noise reduction goal and 

measurement approach. For example, the goal does not include the results of 

noise insulation of homes and schools. As a result, there is insufficient 

performance information about the effects of noise grants and the extent to which 

noise exposure remains a constraint on airport growth.

There has been an increase in the estimated cost of planned noise mitigation 

projects in FAA’s 2011 National Plan of Integrated Airport Systems report to 

Congress, but a number of indicators point to a future decline in demand for 

grants for noise projects. Specifically, the 2011 report, compared to prior reports,

includes a smaller portion of projects in the most significantly noise-impacted 

areas. Further, since the 2001 report, the number of airports planning eligible 

noise projects is down 16 percent, with about half the number of planned 

projects. Additionally, fewer airports are developing new noise compatibility

programs and many of the 234 airports with such programs may be completed. 

For example, 102 of 137 airports with an NCP more than 10 years old received 

no noise grants since 2007, an indication that those airports may have completed 

all eligible projects in those plans. Finally, about a third of the people living in 

significantly noise-impacted areas reside near airports that have not completed, 

and may never complete, an NCP, a necessary step before an airport can use 

noise grants for residential noise insulation. This population, therefore, may 

never be reached by FAA’s grant program. 

View GAO-12-890. For more information, 

contact Dr. Gerald L. Dillingham at (202) 512-

2834 or dillinghamg@gao.gov.
Page i GAO-12-890 Airport Noise Grants

Letter 1 

Background 3

Populations Exposed to Significant Airport Noise Have Declined 

Because of Improvements in Aircraft Technology 9

FAA Is Taking Steps to Ensure that Projects Meet Eligibility 

Criteria, and FAA’s Strategic Noise Goal Is Not Linked to the 

Noise Grant Program 13

Airports Continue to Plan Noise Mitigation Projects, but of a 

Changing Nature 27

Conclusions 35

Recommendation for Executive Action 37

Agency Comments and Our Evaluation 37

Appendix I Objectives, Scope, and Methodology 39

Appendix II GAO Contact and Staff Acknowledgments 41

Table

Table 1: Planned Airport Noise Projects Identified in the National 

Plan of Integrated Airport Systems since 2001 28

Figures

Figure 1: Selected Tools Available to Address Airport Noise 8

Figure 2: Estimated Population Exposed to Various Airport Noise 

Levels, 1975 to 2010 10

Figure 3: Examples of Decrease in Size of Areas Exposed to 

Significant Airport Noise (DNL 65 dB) 12

Figure 4: Airport Improvement Program Projects by Funding 

Category, Fiscal Years 2000 through 2011 15

Figure 5: FAA Noise Grants by DNL Range, since Fiscal Year 1982 17

Figure 6: FAA Noise Grant Beneficiary Goals, Results and Costs, 

Fiscal Years 2005 through 2011 19

Contents
Page ii GAO-12-890 Airport Noise Grants

Figure 7: Planned Noise Project Estimates by Noise Contour as 

Reported in the National Plan of Integrated Airport 

Systems, 2001 through 2011 30

Figure 8: FAA Approval of Noise Compatibility Programs, 1983 to 

2011 32

Abbreviations

ACIP Airports Capital Improvement Plan 

ADO Airports District Offices 

AEDT Aviation Environmental Design Tool 

AIP Airport Improvement Program

CNEL Community Noise Equivalent Level

dB decibel(s) 

DNL Day-Night Average Sound Level 

FAA Federal Aviation Administration

FICAN Federal Interagency Committee on Airport Noise 

GIS Geographic Information System 

INM Integrated Noise Model 

MAGENTA Model for Assessing Global Exposure from Noise of 

 Transport Airplanes

NCP Noise Compatibility Programs 

NEPA National Environmental Policy Act of 1969 

NPIAS National Plan of Integrated Airport Systems 

NextGen Next Generation Air Transportation System

PFC Passenger Facility Charge 

SOAR System of Airport Reporting 

VALE Voluntary Airport Low Emission

This is a work of the U.S. government and is not subject to copyright protection in the 

United States. The published product may be reproduced and distributed in its entirety 

without further permission from GAO. However, because this work may contain 

copyrighted images or other material, permission from the copyright holder may be 

necessary if you wish to reproduce this material separately.
Page 1 GAO-12-890 Airport Noise Grants

United States Government Accountability Office

Washington, DC 20548

September 12, 2012

The Honorable John D. Rockefeller IV

Chairman

The Honorable Kay Bailey Hutchinson

Ranking Member

Committee on Commerce, Science, and Transportation

United States Senate

The number of commercial and general aviation flights in the United 

States is estimated to increase 20 percent by 2024, according to the 

Federal Aviation Administration (FAA). While airports provide access to 

transportation for millions of people each day, airport noise—by, for 

example, interfering with speech, sleep, and student learning—can 

severely diminish quality of life in communities around airports and spur 

community objections to airport operations and continued growth. Since 

1982, to address and mitigate the problems associated with airport noise, 

Congress has provided a dedicated source of funding within the Airport 

Improvement Program (AIP) for noise mitigation projects.1 FAA 

administers the AIP, which has provided nearly $5.8 billion in grants since 

fiscal year 1982 to sound insulate homes and other buildings near 

airports as well as acquire land in, and relocate residents away from, 

significantly noise impacted areas, among other noise mitigation 

activities.2

FAA has an ongoing responsibility to balance the growing demand for 

aviation capacity against the environmental concerns and effects on 

communities caused by airport noise. Aircraft technology, the number of 

aircraft operations, and noise levels have changed markedly since FAA 

first began providing AIP noise grants. Moreover, the implementation of 

FAA’s 2018 strategic goal for noise is to reduce the residential 

population exposed to significant airport noise in the United States to less 

than 300,000 people. AIP-funded noise mitigation projects, administered 

by airports, are FAA’s primary tool to achieve this goal.

 

1

Tax Equity and Fiscal Responsibility Act of 1982, Pub. L. No. 97-248, § 508 (d) (2), 96 

Stat. 324. 

2

FAA defines significant airport noise as at or above a Day-Night Average Sound Level 

(DNL) of 65 decibels (dB). DNL is a generally accepted measure of noise exposure. 

 
 

Page 2 GAO-12-890 Airport Noise Grants

the Next Generation Air Transportation System (NextGen)3

1. How has overall airport noise exposure changed since AIP noise 

grants were first funded?

and the 

growth in aircraft operations that NextGen investments could spur may 

lead to new demand for airport noise mitigation or new noise challenges. 

As a result, it is not clear how well the AIP noise grant program will be 

able to provide an appropriate and effective tool for addressing changes 

in future airport noise exposure. In light of these concerns, you requested 

that we examine FAA’s AIP noise grants. Our report addresses the 

following questions:

2. How have AIP noise grants been used by airports to mitigate noise 

and what have these grants achieved?

3. What is the likely future demand for AIP noise grants?

To describe how airport noise exposure has changed over time, we 

reviewed available literature; assessed the use of FAA noise models; 

interviewed industry, FAA, and airport officials; and, for illustrative 

purposes, performed Geographic Information System (GIS) analysis of 

changes in the areas exposed to airport noise near several large airports. 

To assess how AIP grants have been used by airports for noise mitigation 

projects and planning, we analyzed FAA data in the System of Airport 

Reporting (SOAR). This database includes detailed information about AIP 

grantees, Passenger Facility Charge (PFC) approvals, project types, and 

other information. We performed a data reliability assessment of SOAR 

that included electronic testing, review of FAA documentation, and 

interviews with relevant FAA officials. We found the data to be sufficiently 

reliable for our purposes. To assess the likely future demand for AIP 

noise grants we compiled and analyzed a range of data from different 

sources. Sources included planned projects in the National Plan of 

Integrated Airport Systems (NPIAS),4

 

3

NextGen refers to the transformation of the air transportation system by 2025 from the 

current radar-based system, to a more automated aircraft-centered, satellite-based 

system. 

FAA’s main planning tool for 

identifying future airport capital projects; data on airports’ Noise 

Compatibility Programs (NCPs) and noise exposure maps, both key 

4

The NPIAS may not capture all planned noise mitigation projects that are included in 

other airport planning documents, such as environmental approvals. 
 

Page 3 GAO-12-890 Airport Noise Grants

documents for many AIP noise grants; and FAA’s estimates of the 

population exposed to significant airport noise.5 FAA calculates these 

estimates with models that are broadly used and generally considered 

accurate for the purposes intended. We did not independently assess 

FAA’s models. To illustrate the results of our analysis and better 

understand the real world implementation and future of airport noise 

programs, we reviewed noise programs at seven judgmentally selected 

airports. These airports were selected to represent a range of sizes, 

geographical locations, and use of noise grants. Information gathered 

from these reviews is not generalizable to all airports. We conducted this 

performance audit from October 2011 to September 2012 in accordance 

with generally accepted government auditing standards. Those standards 

require that we plan and perform the audit to obtain sufficient, appropriate 

evidence to provide a reasonable basis for our findings and conclusions 

based on our audit objectives. We believe that the evidence obtained 

provides a reasonable basis for our findings and conclusions based on 

our audit objectives.

Since the late 1950s, noise from aircraft and other airport operations has 

generated controversy within many surrounding communities and can be 

a constraint on airport development and aircraft operations. As we have 

previously reported, noise is one of the top environmental concerns at 

airports.6

 

5

For the purposes of this report, we used the currently accepted definition of significant 

airport noise (e.g., DNL 65+ dB). The results of our analysis of future demand for noise 

grants would change if the definition of significant airport noise changes in the future. 

Most airports are owned and operated by public authorities, 

such as cities, counties, or port authorities, which have primary 

responsibility for addressing community concerns about noise. The 

federal government has a long history of helping airports address noise 

concerns by, for example, defining how airport noise is measured; 

providing a framework for assessing the impact of noise and for airports 

to plan noise mitigation projects; and funding eligible noise mitigation 

projects. Within this context, airports may undertake a range of noise 

mitigation projects. The federal government has also required the use of 

6

GAO, Aviation and the Environment: Impact of Aviation Noise on Communities Presents 

Challenges for Airport Operations and Future Growth of the National Airspace System, 

GAO-08-216T (Washington, D.C.: October 2007); GAO, Aviation and the Environment: 

Systematically Addressing Environmental Impacts and Community Concerns Can Help 

Airports Reduce Project Delay, GAO-10-50 (Washington, D.C.: September 2010). 

Background 
 

Page 4 GAO-12-890 Airport Noise Grants

quieter aircraft technologies. The Aviation Noise and Capacity Act of 1990 

required that all commercial jets at civilian airports switch to Stage-3 

aircraft by the year 2000.7

FAA is charged with implementing and enforcing noise regulations for 

airports’ noise mitigation efforts, including setting the eligibility standards 

to receive federal funding. In 1979, the Aviation Safety and Noise 

Abatement Act charged FAA with establishing regulations for noise 

compatibility planning.

 Airlines phased out the loudest aircraft over 

time, and by 2000, the U.S. commercial fleet was composed of quieter 

aircraft than in the 1990s.

8 In 1984, FAA promulgated regulations, commonly 

referred to as the “Part 150” program, that guide airports’ Noise 

Compatibility Programs (NCP).9 Under these Part 150 regulations, FAA 

has adopted Day-Night Average Sound Level (DNL) as the measure used 

for assessing noise.10 Generally FAA applies DNL 65 dB as the minimum 

level for residential properties to be eligible for federally funded noise 

mitigation.11

 

7

Pub. L. No. 101-508, §9308, 104 Stat. 1388-382 (1990). Federal noise regulations define 

aircraft according to 4 classes: Stage-1, Stage-2, Stage-3, and Stage 4. Stage 1 are the 

loudest, and Stage 4 are the quietest. All Stage 1 aircraft have been phased out of 

commercial operation, and all unmodified Stage 2 aircraft over 75,000 pounds were 

phased out at the end of 1999. The FAA Modernization and Reform Act of 2012 (Pub. L. 

No. 112-95, §506(a), 126 Stat. 11, 105 (2012)) requires the phase out of Stage 2 aircraft 

under 75,000 pounds (general aviation aircraft) by the end of 2015. 

Airport operators must submit noise exposure maps to the 

FAA for review and acceptance before submitting an NCP. These maps 

show, among other things, the airport property, runway location(s), flight 

paths, DNL noise contours at the 65, 70, and 75 dB levels (and the 

8

Pub. L. No. 96-193, §104, 94 Stat. 51 (1980).

9

14 C.F.R. Part 150. 49 Fed. Reg. 49269, December 18, 1984.

10In 1972, the Environmental Protection Agency (EPA) was required to study exposure to 

airport noise (.49 U.S.C. § 44715(a)(2)). EPA’s study identified Day-Night Average Sound 

Level (DNL) as the appropriate measure for assessing cumulative noise in the airport 

environment. DNL is a cumulative sound level in decibels (dB), for the period from 

midnight to midnight, obtained after the addition of ten decibels to sound levels for the 

periods between 10:00 p.m. and 7:00 a.m.

11According to FAA, a lower local standard (e.g., DNL 60 dB) may be used if the standard 

is formally adopted by the local jurisdiction for land-use compatibility and the airport 

sponsor has incorporated it. See, 49 U.S.C. §47504(c)(2)(B)). Where a compatible land 

use plan is adopted outside of the Part 150 process, the land use compatibility plan must 

be developed cooperatively by the airport sponsor and local jurisdiction. 49 U.S.C. §

47141. 
 

Page 5 GAO-12-890 Airport Noise Grants

incompatible land uses and estimates of the population residing within 

those contours), and the location of noise sensitive public buildings, such 

as schools, as defined by FAA regulations.12 For example, residential 

development within the DNL 65+ dB contour is deemed incompatible, 

whereas commercial and manufacturing development is not because of 

the different impacts of noise on people. The NCP documents the noise 

mitigation projects the airport proposes to implement and is submitted to 

FAA for review and approval. The airport may offer mitigation measures 

within incompatible land use areas that meet other eligibility criteria. For 

example, a residence located within a DNL 65+ dB area that also has 

interior noise levels above DNL 45 dB may receive noise insulation. 

Airport participation in the Part 150 process is voluntary. The typical level 

of noise in a suburban residential neighborhood that is not near an airport 

is about DNL 50 dB and an urban residential area is about DNL 60 dB.13

FAA administers two programs that fund airports’ capital development 

projects, including noise-related projects. With the creation of the AIP in 

1982, FAA had a source of funds to provide grants to airports for noise 

mitigation projects. Congress reserved a set-aside specifically for noise 

projects that is currently funded at no more than $300 million per year, but 

has also expanded over time to include other types of environmental 

projects including water projects at airports undertaken as a result of an 

environmental record of decision for an airport development project and 

 

12Noise Exposure Maps show noise contours surrounding an airport that depict specified 

levels of noise and look similar to a land elevation map. The number of operations, runway 

orientation and use, the type of aircraft, and time of day (because night operations have a 

higher multiple/weight in calculating DNL) are the fundamental drivers of the size and 

shape of an airport’s noise contour. 

13DNL is a noise descriptor or metric that takes into account the magnitude of the sound 

levels of all individual events that occur during a 24-hour period, the number of events, 

and an increased sensitivity to noise during typical sleeping hours (between 10:00 p.m. 

and 7:00 a.m.) Although FAA requires the use of DNL for airport analyses, it also 

promotes the use of supplemental metrics, which according to the Federal Interagency 

Committee on Aviation Noise, are also useful in addressing various public noise concerns 

and helping the public to further understand airport-related noise impacts.
 

Page 6 GAO-12-890 Airport Noise Grants

certain types of air quality projects.14 Capital projects in approved NCPs 

that meet AIP criteria are eligible for AIP grants. Further, airports can be 

awarded AIP noise grants for some types of noise mitigation projects 

without an NCP. First, in 2003, AIP noise grant eligibility was temporarily 

expanded by permitting FAA to provide grants to state and local 

governments for land use compatibility planning and noise mitigation 

projects around large and medium hub airports if the airport had not 

submitted a Part 150 study or had not updated its NCP for more than 10 

years.

15

 

14Pub. L. No. 97-248, §505, 96 Stat. 676 (1982). The AIP is funded by congressional 

appropriation from the Airport and Airway Trust Fund which is principally funded by a 

variety of excise taxes paid by users of the national airspace system. Under FAA’s current 

authorization, 35 percent of the annual AIP discretionary budget, up to $300 million, is 

reserved for airport noise mitigation projects, including noise compatibility planning and 

implementation of noise compatibility programs, and other approved environmental 

projects. The upper limit is a new statutory provision enacted as part of the FAA 

Modernization and Reform Act of 2012 49 U.S.C. § 47117(e)(1)(A). Airports that accept 

AIP grants for airport development commit to several assurances, include taking steps, to 

the extent practicable, to restrict use of land adjacent to airports to activities and purposes 

compatible with normal airport operations. 49 U.S.C. 47107.

Second, the National Environmental Policy Act of 1969 (NEPA), 

as amended, requires federal agencies to examine the potential impacts 

associated with a proposed federal action, including potential noise 

impacts. As a result, airport development proposals, such as adding new 

runways or otherwise expanding capacity, must be reviewed for the 

potential environmental effects as fully as technical, economic and other 

considerations. Likewise, operational changes, such as changes in flight 

paths, may trigger a similar review process, depending on the extent of 

the likely noise impact. These reviews may require airports to prepare an 

environmental assessment or may require the FAA to prepare an 

environmental impact statement which could, in turn, lead to a noise 

mitigation project that is eligible for AIP funding. Airports must match AIP 

15In such cases, the airport sponsor must agree and provide necessary documentation. 

Vision 100: Century of Aviation Reauthorization Act, Pub. L. No. 108-176, § 160(a), 117 

Stat. 2511 (2003). This provision was later extended by the FAA Modernization and 

Reform Act of 2012 to September 30, 2015. Pub. L. No. 112-95, § 153. 
 

Page 7 GAO-12-890 Airport Noise Grants

grants to varying degrees, depending on an airport’s size.16 The second 

FAA funding program for noise mitigation projects is the Passenger 

Facility Charge (PFC) program.17

There are a variety of projects and actions to mitigate and reduce airport 

noise that airports may use, some of which are eligible for AIP grants. 

See figure 1.

This program allows publicly operated 

airports to charge passengers a fee and retain these fees for their use on 

FAA-approved projects, including those that reduce noise. Project 

eligibility criteria for the PFC and AIP programs are largely the same, 

although an NCP is not required to use PFC funds for noise mitigation 

projects. PFC funds can be used to match AIP grants.

 

16FAA’s authorizing statute categorizes the nation’s primary airports into four main groups 

based on the number of passenger enplanements—large hubs, medium hubs, small hubs, 

and nonhubs. The categories are based on the number of passengers boarding an aircraft 

(enplaned) within the United States. A large hub enplanes at least 1 percent of all 

systemwide passengers, a medium hub at least 0.25 but less than 1 percent, a small hub 

at least 0.05, but less than 0.25, and a nonhub less than 0.05 percent. See 49 U.S.C. § 

47102 (10), (12), and (23) respectively. Historically, noise mitigation projects were eligible 

for 80 percent funding under AIP for large- and medium-hub airports, and 90 percent 

funding at small, non-hub, general aviation, and reliever airports 49 U.S.C. § 47109. 

Between 2004 and 2011, the federal share for smaller airports was temporarily increased 

to 95 percent under Vision 100-Century of Aviation Reauthorization Act (Pub.L. No. 108-

176), but that increased level expired with the passage of the FAA Modernization and 

Reform Act of 2012. 

1749 U.S.C. §40117.
 

Page 8 GAO-12-890 Airport Noise Grants

Figure 1: Selected Tools Available to Address Airport Noise

a

Beginning October 1, 1998, FAA only approves noise mitigation measures for incompatible 

development existing as of that date.

b

FAA Modernization and Reform Act of 2012 allows FAA to provide noise grants for airports to 

complete environmental reviews and assessment activities for proposals to implement flight 

procedures as part of an airport noise compatibility program (Pub. L. No. 112-95, § 504).
 

Page 9 GAO-12-890 Airport Noise Grants

The number of people exposed to airport noise has been steadily 

declining for several decades, according to FAA. FAA uses a model, 

called Model for Assessing Global Exposure from Noise of Transport 

Airplanes (MAGENTA), to calculate a high-level national estimate of the 

population exposed to different levels of airport noise. MAGENTA uses, 

among other factors, airport-level information about the number of aircraft 

operations, types of aircraft, flight paths, and census data for communities 

near airports (see sidebar). Individual airports may have, through Part 

150 studies or through studies undertaken for NEPA compliance, for 

example, more precise estimates. FAA estimates that approximately 7 

million people lived in areas exposed to significant airport noise—DNL 65 

dB or higher—in 1975. Through the 1980s and 1990s, this exposure 

declined to less than a million by the year 2000. FAA estimates that about 

309,000 people currently live in areas at or above DNL 65 dB. FAA 

estimates also show declines in the populations exposed to nonsignificant airport noise (i.e., below DNL 65 dB). For example, FAA 

estimates that between 2000 and 2010 the number of people residing in 

areas with DNL 60 to 65 dB decreased from about 3 million to 1.5 million 

(see fig. 2). The downward trend in noise exposure has held relatively 

steady despite overall increases in air traffic. For example, total U.S. 

operations—including arrivals and departures—went up from 

approximately 17.4 million in 2000 to 20.8 million in 2011, though some 

locations have seen declines.

Populations Exposed 

to Significant Airport 

Noise Have Declined 

Because of 

Improvements in 

Aircraft Technology
 

Page 10 GAO-12-890 Airport Noise Grants

Figure 2: Estimated Population Exposed to Various Airport Noise Levels, 1975 to 2010

Note: Population exposure estimates include residents that have and have not received noise 

insulation treatment. Data on DNL 55 dB+ and DNL 60 dB+ were not available for years prior to 2000.

FAA’s model is intended to determine the population living within 

geographic areas exposed to airport noise, regardless of whether the 

houses or apartments have been sound insulated using AIP, PFC, or 

other funds. Consequently, some percentage of the population that FAA 

estimates is exposed to DNL 65 dB or higher lives in structures that have 

benefited from noise insulation. There are no readily available data to 

determine this percentage. Thus, FAA’s model cannot be used to 

specifically assess the results of AIP grants.

As with the shrinkage in the populations living in noise-exposed areas, 

the geographic areas exposed to significant noise around airports have 
 

Page 11 GAO-12-890 Airport Noise Grants

also generally been shrinking based on multiple recent assessments of 

DNL 65 dB noise contours that we, FAA officials, and others have 

conducted.18 Likewise, FAA and airport officials, as well as industry 

representatives with whom we spoke generally agreed that the DNL 65 

dB noise contours around airports have been shrinking. We did not 

perform an overall assessment of the extent of this change because noise 

exposure maps are updated at different times at the discretion of 

individual airports. At all seven of the airports we examined—including 

two airports that have recently added runways—noise contours have 

shrunk overall, according to airport officials or our assessments of noise 

exposure maps for these airports.19

 

18GAO, Aviation and the Environment: Impact of Aviation Noise on Communities Presents 

Challenges for Airport Operations and Future Growth of the National Airspace System, 

For example, at Atlanta-Hartsfield 

airport, the DNL 65 dB contour has become smaller since the 1980s 

despite a tripling of airport operations. Likewise, at Seattle-Tacoma 

International airport, noise contours are substantially smaller today than in 

the past. Specifically, the DNL 65 dB contour decreased in area almost 

60 percent, from approximately 14 to 6 square miles, from 1998 to 2009. 

However, while noise exposed areas have generally become smaller 

overall, the shapes of some contours may have changed or shifted over 

time, decreasing significant noise exposure in some areas, but also 

exposing new areas to significant noise. For example, while the DNL 65 

dB area around Los Angeles International airport decreased from 

approximately 13 to 11 square miles in total area from 1987 to 2011, the 

shape of the contour changed and now includes different communities 

(see fig. 3).

GAO-08-216T (Washington, D.C.: October 2007). Airport Cooperative Research Program, 

Aircraft Noise: A Toolkit for Managing Community Expectations, ACRP Report 15 

(Washington, D.C.: 2009). 

19We examined Atlanta-Hartsfield (ATL), Birmingham-Shuttlesworth (BHM), Burbank 

(BUR), King County International – Boeing Field (BFI), Los Angeles International (LAX), 

Ontario International (ONT), and Seattle-Tacoma International (SEA). To some extent, 

comparing noise contour maps over time is a judgmental process because the methods 

and assumptions used in producing maps at different points in time change. For example, 

newer maps maybe generated, in part, with data from noise monitors that were not in 

place when older maps were made. However, to illustrate a broad trend, we compared the 

DNL 65 dB (Community Noise Equivalent Level, or CNEL, in California) contours of 

available maps, using Geographic Information System (GIS) analysis when possible. 

CNEL, like DNL, is used to characterize average noise levels, but uses a somewhat 

different methodology.
 

Page 12 GAO-12-890 Airport Noise Grants

Figure 3: Examples of Decrease in Size of Areas Exposed to Significant Airport Noise (DNL 65 dB)

Improvements in aircraft technology, spurred by federal mandates and 

industry actions to reduce aircraft noise levels, have been the largest 

contributor to the shrinkage in airport-noise-exposed populations and 
 

Page 13 GAO-12-890 Airport Noise Grants

noise contours.20 FAA and airport officials we spoke with generally agreed 

that the phase out of the loudest aircraft—specifically, stage 1 and stage 

2 aircraft weighing over 75,000 pounds—by 2000 and improved aircraft 

and engine technology are the most significant factors causing noise 

contours to shrink. For example, reduced air velocity moving through 

improved engines has reduced engine noise. Likewise, acoustical liners 

and improved air flap designs have reduced airframe noise.21 Other 

factors that may have contributed to decreased airport noise exposure 

include the implementation of flight procedures that can, for example, 

direct air traffic over less populated areas during arrivals and departures.

AIP noise grants have been widely used by airports and have provided 

noise mitigation to thousands of people. However, in recent years, the 

program has benefited fewer people and FAA has not met its program 

goals. In light of the shrinking airport noise contours discussed above, 

FAA’s enforcement of grant eligibility criteria—related to noise exposure 

maps and the assessment of interior residential noise—creates a risk that 

some noise grants may not have met eligibility criteria, especially in the 

edges of the noise contour where noise may be below DNL 65 dB. FAA 

has recently issued guidance to address these areas of grant eligibility 

criteria, which if followed should reduce the risk of making ineligible 

grants. In addition, FAA’s overall strategic goal for its noise-related 

activities is not linked to the results of noise grant investments.

Since fiscal year 1982, FAA has provided about $5.8 billion in AIP noise 

grants to 481 commercial and general aviation airports, reflecting broad 

participation in the program by airports through the program’s history. 

Specifically, most primary airports have been awarded at least one noise 

grant. General aviation airports have received $75 million in grants since 

fiscal year 1982. Airports that have completed voluntary Part 150 studies 

and have had an NCP approved by FAA have received the majority of 

 

2049 U.S.C. § 47528. The importance of technological advancement in reducing airport 

noise exposure has been comprehensively addressed by the National Academies of 

Sciences. National Research Council, For Greener Skies: Reducing Environmental 

Impacts of Aviation (Washington, D.C.: 2002). 

21FAA seeks to achieve source noise reduction through programs such as the Continuous 

Lower Energy, Emissions and Noise (CLEEN) program as well as through operational and 

procedure changes. 

FAA Is Taking Steps 

to Ensure that 

Projects Meet 

Eligibility Criteria, 

and FAA’s Strategic 

Noise Goal Is Not

Linked to the Noise 

Grant Program

Grants Are Widely Used 

for Noise Insulation 

Projects and Land 

Acquisition
 

Page 14 GAO-12-890 Airport Noise Grants

AIP noise grant funding.22 As of May 2012, 234 airports had an approved 

NCP and received grants totaling about $5 billion.23 Primary commercial 

airports account for 168 of the 234 approved plans. Of the remaining 66, 

62 are larger general aviation or reliever airports.24 Additionally, grants 

have been awarded to airports and communities outside the Part 150 

framework following statutory changes in 2003 that allow for such 

grants.25

AIP noise grants have funded a range of different types of projects, 

reflecting FAA and airport priorities, with noise insulation and land 

acquisitions receiving the most support. From fiscal year 2000 through 

2011, out of approximately $3.2 billion total, residential and public building 

noise insulation projects received approximately $1.7 billion and $456 

million, respectively; property acquisition projects received $780 million 

(see fig. 4). In addition, since fiscal year 2000, FAA has approved PFC 

applications from 73 airports to collect nearly $2 billion for noise mitigation 

projects.

During fiscal years 2005 through 2011, grants totaling $336 

million have been awarded to 24 airports or communities that do not have 

NCPs. These grants went to some of the largest airports in the country. 

For example, the Port Authority of New York and New Jersey secured 

$134 million in grants for noise insulation of public buildings—mostly 

schools—near Teterboro, Newark, LaGuardia, and Kennedy airports.

 

22As previously discussed, noise grants can be awarded following FAA approval of a Part 

150 NCP, agreements that are made pursuant to certain environmental review studies, or 

via other statutory provisions that allow certain projects to be funded without Part 150 

approvals. FAA’s Office of Airport’s System of Airports Reporting (SOAR), a central data 

system, does not track the underlying justification for each grant and airports may have 

performed both Part 150 and environmental reviews. 

23101 airports have been awarded AIP noise grants for planning purposes, but have not 

subsequently been awarded grants for capital projects, such as noise insulation or land

acquisition. 

24A primary airport is a commercial airport with more than 10,000 passenger boardings 

each year. 49 U.S.C. § 47102(15). A reliever airport is an airport designated by the 

Secretary of Transportation to relieve congestion at a commercial airport and provide 

general aviation access to the overall community. 49 U.S.C. § 47102(22). A reliever 

airport may be publicly or privately-owned. 

25Vision 100: Century of Aviation Reauthorization Act, Pub. L. No. 108-176, § 160(a), 117 

Stat. 2511 (2003) 
 

Page 15 GAO-12-890 Airport Noise Grants

Figure 4: Airport Improvement Program Projects by Funding Category, Fiscal Years 

2000 through 2011

Note: Other includes various project categories listed above, but FAA data do not specify project-type 

funding levels.

The distribution of funds reflects airport priorities and FAA’s project 

assessments based on AIP grant-scoring formulas as well as judgmental 

considerations. FAA’s grant scoring formula ranks proposed projects in 

higher DNL areas above lower DNL areas and at larger airports above 

smaller airports. For example, a proposed residential noise insulation 

project in the DNL 70-74 dB range would score higher than a project in 

the DNL 65-69 dB range, regardless of airport hub size. In addition to 

formula scores, FAA made grant award decisions based on judgmental 

factors such as input from regional FAA officials—such as FAA’s Airports 

division regional offices or Airports District Offices (ADO)—about an 

individual airport’s capacity to execute its proposals and consideration of 

FAA regional priorities, as well as to meet national priorities. In recent 

years, FAA has also considered information on the number of expected 

beneficiaries—whether residents, students, or other groups—and 

attempted to fund a mix of grants that will meet an annual beneficiary 

goal. These beneficiary goals, discussed later in this report, are 

measured in the number of people expected to benefit from awarded 

grants. The fiscal year 2012 goal was 15,000 people.
 

Page 16 GAO-12-890 Airport Noise Grants

In the first decades of the program, noise grants largely went to projects 

in areas most significantly impacted by airport noise—generally areas 

closest to airports—while grants in more recent years have gone to 

projects in areas that are less significantly impacted, but still deemed to 

be exposed to DNL 65 dB or higher noise levels (see fig. 5). For example, 

based on FAA data, all 385 acquisition and noise insulation grants from 

fiscal year 1982 through 1991 went to projects in DNL 75 dB or higher 

areas. In the last 12 years, as areas of higher noise exposure were 

increasingly already addressed, a large majority of grants went to projects 

in DNL 65-69 dB areas, the lowest significant noise-level eligible for 

grants under the program.26

 

26The DNL of these projects refers to the noise level stipulated for the project by the 

airport sponsor based on, for example, the noise exposure map and additional 

documentation required closer to the date of the grant award.

Also, most of the grants for planning activities 

were awarded in the first half of the program’s history. Specifically, 

through fiscal year 2000, FAA awarded 332 planning grants for 

approximately $50.3 million. As of 2000, 195 airports had approved 

NCPs. Since fiscal year 2000, FAA has awarded 117 grants totaling 

approximately $45.5 million for planning. Since 2001, thirty-nine airports 

had new NCPs approved by FAA. In some cases, instead of conducting a 

Part 150 noise study, airports completed environmental impact 

statements for major proposed development that included developing 

noise exposure maps that could be used to identify mitigation projects 

eligible for AIP noise grants.
 

Page 17 GAO-12-890 Airport Noise Grants

Figure 5: FAA Noise Grants by DNL Range, since Fiscal Year 1982

Note: 124 grants totaling $124.6 million did not specify the DNL level of the projects (“noise mitigation 

measures”) and are excluded from this analysis.

Consistent with the grant trends discussed above, according to FAA and 

airport officials with whom we spoke, planned projects within individual 

airport noise programs were prioritized to first address the most noise 

impacted areas or specific project types. At all of the seven airports we 

visited, officials indicated that they began mitigation efforts with properties 

in the noisiest areas that are typically closest to the airport or with 

schools. For example, Burbank (Bob Hope) Airport in California first 

insulated most of the schools inside the DNL 65 dB contour before 

beginning residential noise insulation. At Boeing Field in Seattle, 

residences in areas above DNL 70 dB were generally insulated first. 

However, airport officials also noted that project selection can also 

depend on practical program considerations, not simply noise exposure. 

For example, before starting a residential insulation project, the airport 

sponsor must identify and sign up homeowners and complete other 
 

Page 18 GAO-12-890 Airport Noise Grants

planning steps—all of which take time—and could lead to noise insulation 

of homes in areas with lower noise before homes in higher noise areas 

simply because they cleared these steps more quickly.

As part of managing the grant program, FAA sets beneficiary goals for 

AIP noise grants and tracks progress towards those goals. Beneficiary 

data, assessed annually, are used as part of FAA’s annual budget 

justification to Congress. These data aggregate the number of people 

who have been—or are expected to be—relocated following acquisitions, 

as well as residential and student population soundproofing beneficiaries 

as a result of the grants awarded that year. Based on this information, 

noise grants have helped reduce or mitigate airport noise exposure for 

thousands of people.27

 

27FAA does not collect information on the results of noise mitigation projects that are 

funded exclusively with PFC or other local sources of funds. The results FAA reports for 

AIP grants include accomplishments that came, in part, because of local matching funds, 

such as PFCs. 

However, as shown in figure 6, in recent years, 

fewer beneficiaries have been reached by these grants, FAA has fallen 

short of its beneficiary goals, and results have come at a higher per 

beneficiary cost. For example, in fiscal year 2011, the awarded noise 

grants benefited 10,913 people, short of the goal of 15,000, at nearly 40 

percent higher per beneficiary costs than in fiscal year 2005. FAA officials 

explained that these trends are partly attributable to increasing 

construction costs due to inflation and more projects in higher cost areas, 

such as San Diego and Los Angeles. Finally, as discussed more below, 

these results are not reflected in FAA’s overall reporting on the population 

exposed to significant airport noise.
 

Page 19 GAO-12-890 Airport Noise Grants

Figure 6: FAA Noise Grant Beneficiary Goals, Results and Costs, Fiscal Years 2005 

through 2011

Note: Beneficiaries include both residential and student populations that received noise insulation, 

relocation, or other benefits. Total Airport Improvement Program noise grants excludes Voluntary 

Airport Low Emissions grants that do not provide noise beneficiaries.

AIP noise grants have been the most important source of funding for 

noise mitigation projects, but other funding sources have also been used. 

Officials representing all seven of the airports we reviewed agreed that 

AIP funds were of great importance to their noise mitigation programs and 

most stated that, in the absence of these funds, much less, if anything, 

would likely have been spent on such projects. For example, Boeing Field 

does not collect PFCs, and according to airport officials, its noise 

mitigation program is highly dependent on AIP funds. However, many 

airports do have other funding sources—primarily PFC funds—that can 

be used for noise mitigation projects. According to FAA and airport 

officials, PFC funds are most commonly used to provide the local 

matching funds required of AIP grantees. For example, officials at five of 

the six airports that we reviewed that collect PFCs indicated that PFCs 

were used for noise mitigation projects as a match to AIP grants. PFCs 

also have been used to supplement AIP funds. FAA officials indicated 

that PFC funds may be used to speed up the completion of planned noise 
 

Page 20 GAO-12-890 Airport Noise Grants

mitigation projects in light of limited availability of AIP grants. However, 

most officials agreed that projects essential to the continued operations of 

the airport, such as runway rehabilitation and maintenance, were typically 

a higher priority for PFCs than noise mitigation projects. FAA’s existing 

data system does not distinguish between projects that are fully funded 

using PFCs from those where PFCs are used to match AIP grants or 

provide supplemental funding.

We found that many of the FAA-accepted maps used to determine project 

eligibility for noise grants are outdated and could overstate the actual size 

of the DNL 65+ dB areas around airports, putting some federal grant 

investments at risk of funding projects that do not meet the eligibility 

criteria. Following the passage of the Vision 100 Act in 2003,28 airports 

have been required to update noise exposure maps when a change in 

airport operations would indicate that the maps on file with FAA no longer 

accurately show the size or shape of the airport’s DNL 65 dB noise 

contours and relationship to land uses. Federal regulation defines a 

significant change as a 1.5 decibel increase or decrease in the DNL for a 

substantial land area exposed to airport noise. Additionally, if the maps on 

file with FAA are older than 5 years, then the airport must certify that the 

maps continue to accurately reflect current conditions.29

• Most maps that could be used for noise grant eligibility are more than 

5 years old. According to FAA data, of the 252 airports that have 

developed noise exposure maps accepted by FAA, 189 maps are 

FAA officials 

explained that maps over 5 years old should be periodically reviewed for 

potential inaccuracies or changed conditions. In light of the general 

shrinkage in DNL 65 dB contours, some of the FAA-accepted maps are 

outdated and therefore could be inaccurate:

 

28Previously airports had been required to update maps only when there was an increase 

in the contours that would create a substantial new incompatible land use. 

29Prior to 2003, program criteria indicated that maps should accurately reflect conditions 

and be revised when changes occurred, but did not require a revised map when changes 

resulted in decreases in noise exposure. Part 150 requires preparation of “current” and 

“forecast” condition maps. The current condition map reflects conditions—operations, 

fleets, etc.—at the time of the study while the forecast condition map uses estimates of 

conditions at least 5 years in the future. Either map can be used for AIP grant eligibility 

provided it accurately reflects conditions.

Outdated Noise Exposure 

Maps and Inconsistent 

Application of Interior 

Noise Standards Increase

Risks for Noise Grant 

Funds 
 

Page 21 GAO-12-890 Airport Noise Grants

more than 5 years old.30

• Many airports with old maps continue to be awarded noise grants for 

residential noise insulation in DNL 65-69 dB designated areas—the 

area that would first drop out of grant eligibility because of shrinking 

noise contours. Of the 28 airports that were awarded noise grants for 

this purpose in 2010 or 2011, 10 have maps from 2000 to 2005. In 

addition, nine of the 126 airports with maps from 1999 or before 

received a total of $87.6 million in grants in fiscal years 2010 and 

2011 for residential insulation projects in the DNL 65-69 dB area of 

the official map.

Further, we found 126 airports with maps 

from 1999 or before, predating the phase-out of stage 2 commercial 

aircraft by the year 2000. To the extent that the contours depicted by 

these maps reflect conditions from when these louder aircraft 

operated, the actual noise exposed area today is likely smaller.

• Some airports have produced separate noise maps for reasons 

unrelated to Part 150 noise compatibility planning, such as to meet 

state requirements or for environmental reviews.31 In some cases, 

these maps indicate that noise-exposed areas have decreased, but 

FAA has not required the airport to update the map used for AIP 

eligibility. For example, Ontario International’s noise mitigation 

program area is currently defined by a map from 1990, but to meet 

state noise requirements, the airport produces quarterly noise 

exposure maps. While the technical details of the FAA-accepted map 

and these quarterly maps differ, preventing exact comparisons, the 

area exposed to significant noise in the more recent maps covers very 

little residential land across a much smaller area than in the 1990 

map.32

 

3018 of the airports that developed noise exposure maps have not developed an NCP, 

and as will be discussed later in this report, an airport that no longer intends to request 

noise grants may not update its NCP and therefore, its noise maps.

The program has received $25.8 million in grants since fiscal 

year 2007 and has identified $58.4 million in planned AIP-funded 

noise mitigation projects for fiscal years 2013 through 2017.

31Noise exposure maps developed as part of environmental reviews can be used for AIP 

grant eligibility.

32While the methodologies used to develop noise maps for California’s requirement and 

for FAA grant eligibility may differ, both types of maps were developed using FAA’s 

Integrated Noise Model. Therefore, each methodology may produce somewhat different 

noise contours , but the overall trend in the size of the contour should be similar. 
 

Page 22 GAO-12-890 Airport Noise Grants

These indicators suggest that some risk of funding projects that do not 

meet eligibility criteria exists. Without current and accurate noise maps, or 

documentation of an alternative project justification, such as 

environmental agreements, there is no readily available way to determine 

how many, if any, FAA-funded projects did not meet the requirement of 

being inside the DNL 65 dB contour at the time of funding, though FAA 

officials believe that few, if any, grants have funded projects to date that 

do not meet the eligibility criteria.

33

Because an airport has little incentive to update a map that might 

overstate noise exposure, as it might disqualify projects planned by the 

airport from future grants, it is important that FAA enforce the requirement 

that airports maintain appropriately updated or certified noise exposure 

maps. As illustrated by the examples above, FAA has not always done 

so. For oversight purposes, FAA’s 24 regional and district airports offices 

are primarily responsible for assessing the continued accuracy of noise 

exposure maps. In our site visits, we found that FAA district officials were 

generally informed about noise conditions at airports, potentially obviating 

the risk of funding ineligible projects, although we also found examples of 

lax enforcement as well.34

 

33The annual data FAA collects on beneficiaries includes DNL designations for the areas 

in which individuals reside and, to the extent that some grants went to projects that did not 

meet eligibility criteria as discussed previously, beneficiary results would be overstated. 

Some local FAA officials we met with said they 

had reviewed additional information, such as other noise maps from 

environmental reviews, and determined that the requested grants 

targeted projects that remained in significantly noise affected areas. 

Officials explained during our site visits that these assessments are 

partially a judgmental process based on their knowledge of an airport’s 

unique circumstances. For example, district officials determined that 

Seattle-Tacoma airport did not need to update its noise exposure map 

until after the addition of a third runway, a project that involved a 

comprehensive environmental review that included developing noise 

exposure maps. In this case, as in others we identified during our site 

visits, the maps developed as part of this review were used to meet AIP 

grant eligibility requirements. However, in our site visits, we found that 

each district office made different judgments about when to require an 

updated map. In one case, a district office allowed noise maps that were 

34We did not assess the extent that FAA officials in other districts consulted additional 

information in similar circumstances nor did we evaluate FAA’s review of individual grant 

requests.
 

Page 23 GAO-12-890 Airport Noise Grants

known to be inaccurate to be used in an effort to continue funding an 

existing airport’s noise mitigation program. Several airport officials 

acknowledged that the maps used in their AIP funded noise program 

could overstate current exposure. Some airport officials we spoke with 

explained that they were reluctant to update maps when doing so could 

limit AIP eligibility for planned projects that the airport has already 

promised residents. Airport and FAA officials explained that planned 

project areas, as reflected in noise maps, need to be somewhat stable. 

They emphasized that while noise exposure is constantly evolving, it 

takes time to define a program, receive a grant, enroll people, and then 

design and execute projects. According to these officials, planned 

projects represent promises to communities, making program stability 

important. Changing or canceling planned projects because of decreasing 

noise can create public relations problems for airports, especially since 

gradual decreases in DNL may be difficult for residents to perceive. In 

light of these considerations, airport sponsors are unlikely to limit projects 

to only those that clearly meet program criteria without FAA’s insistence. 

FAA, however, is responsible as the steward of the program for insuring 

that AIP noise mitigation funds only support projects that meet the 

program’s eligibility criteria. Because the program has limited funding, 

paying for noise mitigation that is no longer needed takes money away 

from eligible projects that did not receive funding or from other aviation 

priorities.

Furthermore, program criteria—including regulations and FAA guidance—

require that only homes located in DNL 65 dB areas with interior noise 

levels above DNL 45 dB can be approved for noise treatment, with limited 

exceptions, such as neighborhood equity. For example, FAA’s principal 

guidance on AIP implementation explains that the design goal of 

residential noise insulation should be to achieve a noise level of 45 

decibels in all habitable rooms; homes with interior noise levels already 

below this level should not generally receive noise insulation.35

 

35Homes that are below DNL 45 dB can be treated with some insulation to assure 

conformity of improvements and perceived equity of application in the project 

neighborhood. Additionally, within the airport industry, there is some disagreement and 

confusion about whether the 45 DNL noise level is a design goal or a grant eligibility 

requirement.

This 

guidance does not explain the method by which a project sponsor needs 

to assess interior noise levels. FAA district officials told us that the only 

practical way to determine interior noise levels is with testing. FAA 
 

Page 24 GAO-12-890 Airport Noise Grants

officials indicated that airport sponsors generally conduct interior noise 

testing on a sample of homes to determine eligibility based on the 45 dB 

criterion and to assist in designing acoustical treatments, but 

acknowledged that not all airports and consultants were consistently 

applying these rules. We found that interior noise assessments to 

determine project eligibility had been conducted at only three of the six 

airports we visited with residential noise insulation programs. Two of the 

three airports tested samples of homes, and officials at one of these 

airports noted that, to date, no homes have been excluded based on 

testing results because all had tested above DNL 45 dB. The third 

airport’s program included interior noise assessment for all homes in the 

DNL 65-69 dB contour to determine eligibility prior to including a home in 

the insulation program. In that program’s current phase—focused on 

homes in the DNL 65-69 dB contour in the airport’s noise exposure 

map—less than half of the homes qualified for insulation following testing. 

We also found that testing protocols differed at these three airports. For 

example, some tests used artificial noise to simulate aircraft noise while 

other test procedures relied on actual flyovers. The other three airports 

we visited did not conduct interior noise assessments for eligibility, but did 

do some testing for project design purposes. However, without 

information on testing practices at all airports performing residential noise 

insulation, we cannot determine the extent of the risk to federal

investments or how much, if any, AIP noise grant funding has gone to 

projects that did not meet the eligibility criteria. 

Residential noise insulation projects may not have been limited to 

residences that have interior noise levels above DNL 45 dB because FAA 

has not consistently and routinely implemented criteria on interior noise 

level assessment. These criteria do not delineate requirements and 

protocols in detail. FAA officials explained that implementation has been 

inconsistent because airport officials, airport consultants, and FAA district 

officials have different interpretations of existing program criteria. FAA 

guidance did not, for example, specify testing protocols fully. Further, as 

with updating noise maps, there are disincentives for airports to rigorously 

implement existing criteria. For example, as a result of assessments 

some residents may not receive expected benefits, such as acoustical 

doors, windows, and ventilation systems. Airport officials often have to 

deal with community discontent when they explain why some residents 

are eligible for noise insulation and others are not.

At the time of our review, FAA, recognizing concerns about the age of 

noise exposure maps and the inconsistent implementation of interior 

testing criteria, issued program guidance in August 2012 to clarify existing 
 

Page 25 GAO-12-890 Airport Noise Grants

requirements regarding noise mitigation.36 According to FAA officials, the 

guidance reinforces existing criteria on grant eligibility regarding the age 

and accuracy of noise exposure maps and clarifies the DNL 45 dB interior 

noise eligibility criteria. The guidance also addresses how interior noise 

should be measured and will provide for a 3-year transition period that will 

allow airports to continue with promised noise mitigation projects while 

better aligning projects slated for 2014 and beyond with the eligibility 

criteria. It is unclear whether FAA will fund projects during the transition 

period that do not demonstrably meet program eligibility criteria. FAA 

previously identified similar concerns about fund use and issued clarifying 

guidance. Namely, the problems we found regarding potentially 

inaccurate and old noise exposure maps were also identified in a 2002 

internal FAA study.37 Specifically, the study found that in fiscal years 2000 

and 2001, grants were provided to airports based on potentially 

inaccurate maps from the 1980s and early 1990s that pre-dated the 

stage-2 aircraft phase-out. The study indicated that, because of shrinking 

contours, some grants may have funded projects in moderately noise 

impacted areas (DNL 55 to 64 dB) that should not have been funded. To 

address this issue, in 2003, and again in 2005, FAA issued program 

guidance requiring that all grant decisions be based on noise exposure 

maps that are less than 5 years old or otherwise certified as a reasonable 

representation of conditions at the airport. Therefore, it will be important 

that FAA enforce and its district offices adhere to the new guidance to 

ensure that noise grants are both eligible and targeted to the highest 

needs.

FAA has established an overall agency goal for addressing airport 

noise—which covers all noise-related agency efforts, not just the AIP 

noise grant program—to reduce the population living in significantly noise 

impacted areas to below 300,000 people nationwide by 2018.38

 

36Program Guidance Letter 12-09, AIP Eligibility and Justification Requirements for Noise 

Insulation Projects (Aug. 17, 2012)

This goal 

37Federal Aviation Administration, “Evaluation of Noise Set Aside Portion of the Airport 

Improvement Program,” (Oct. 1, 2002).

38This agency goal is defined as residential populations living in DNL 65+ dB areas. As 

discussed earlier, the declining trend in the population exposed to significant airport noise 

are largely attributable to quieter aircraft that result in smaller noise exposure contours. 

Current exposure is estimated at about 309,000.

FAA’s Strategic Goal for 

Noise Reduction Is Not

Linked to Noise Grant 

Program
 

Page 26 GAO-12-890 Airport Noise Grants

is articulated in the Department of Transportation’s fiscal year 2013 

performance plan, FAA’s long-range strategic plan—Destination 2025—

and other FAA performance documentation. The intended outcome of 

reaching this goal is to ameliorate community noise concerns such that 

they are not a constraint on airport growth. To achieve this goal and 

outcome, the department and FAA have indicated that people still 

exposed to significant airport noise levels shall be addressed by AIP 

noise grants, FAA’s largest program to address airport noise, primarily 

though airport-specific Noise Compatibility Programs.

However, the overall strategic goal is not linked to the results of the AIP 

noise grants. We have previously reported that linking program 

performance to overall goals can provide a clear, direct understanding of 

how program results will lead to the achievement of goals. We have also 

reported that to determine whether goals are met, an agency should 

establish performance measures that gauge progress toward desired 

outcomes and can be used as a basis for decision making.39 However, 

with the exception of AIP-funded land acquisition and relocation projects, 

the types of projects funded by AIP noise grants are not intended to lower 

the number of people living in significantly noise-impacted areas, but 

rather mitigate the negative impacts of airport noise exposure.40

 

39GAO, Executive Guide: Effectively Implementing the Government Performance and 

Results Act, 

In other 

words, noise grant results will not help the agency achieve its goal, as 

articulated. Further, by articulating its goal strictly in terms of the 

residential population exposed to significant airport noise, FAA has 

established a strategic goal that does not account for the results of its 

largest noise program. Specifically, neither the goal nor FAA’s use of the 

MAGENTA tool to measure progress toward that goal by estimating the 

population exposed to different levels of airport noise reflects AIP noise 

grant results:

GAO/GGD-96-118 (Washington, D.C.: June 1996). 

40Through 2005, FAA monitoring of progress towards its strategic goal—namely, annual 

estimates of the population exposed to significant airport noise using the MAGENTA 

model—did include population decreases because of noise grant funded acquisition and 

relocation projects, but these results have not been included in estimates since 2005 

because of an administrative error. FAA is currently taking steps to account for relocated 

populations into estimates again, but expects doing so will lower the overall population 

estimate only slightly. 
 

Page 27 GAO-12-890 Airport Noise Grants

• The residential population goal and associated annual estimates of 

population exposure do not take into account the number of residents 

benefiting from AIP-funded acoustically treated homes. While these 

residents continue to live in a noise impacted area, they do so in a 

quieter home that has benefited from AIP-funded mitigation.

• The goal and measure also do not account for student or other 

populations using public buildings that may be affected by airport 

noise and could benefit from the AIP grant program in the future.

As a result of establishing a strategic goal and a corresponding measure 

of progress that do not account for AIP noise grants results, there is 

insufficient performance information about the nature and extent of 

remaining airport noise exposure and the contribution of noise grants in 

mitigating the impact of that exposure. Specifically, FAA does not know 

how many residences, schools, or other public buildings are in 

significantly noise exposed areas or which of those have yet to benefit 

from noise insulation projects. Without this information, Congress and 

FAA program managers cannot make fully informed decisions about what 

the noise grant program can reasonably be expected to address in the 

future and the extent to which noise exposure remains a constraint on 

growth. FAA officials acknowledged that the current approach could 

cause confusion and that there may be some benefit to better 

distinguishing between the agency’s overall noise goal and the purpose of 

noise grants.

The 2011 National Plan of Integrated Airport Systems (NPIAS) report, 

which includes airport projects from fiscal years 2011 through 2015, 

shows continued plans for noise mitigation projects, but a drop in the 

number of projects and the number of airports planning them. 

Additionally, since the 2001 NPIAS report, the nature of included projects 

has changed, reflecting airports’ progress in implementing their noise 

compatibility programs, and a corresponding drop in the residential 

population living in areas around airports deemed significantly affected by 

noise. The change in the nature and extent of noise mitigation projects in

the NPIAS combined with other indicators—such as the age of NCPs, 

shrinking noise contours, and other factors—points to the possibility of a 

future decline in the demand for noise project funding. Concurrently, the 

scope of projects eligible for the set-aside has expanded to include water 

and emissions projects, whose cost may grow in the future.

Airports Continue to 

Plan Noise Mitigation 

Projects, but of a

Changing Nature
 

Page 28 GAO-12-890 Airport Noise Grants

The NPIAS, which inventories airport projects planned over the next 5 

years, is one indicator of future noise grant demand.41 The most recent 

NPIAS, issued in 2011, illustrates that, as compared to previous years, 

fewer airports are planning fewer noise mitigation projects, albeit at a 

higher total cost. The 2011 NPIAS report to Congress includes planned 

AIP-eligible projects. The number of airports with planned AIP noise 

mitigation projects has declined 16 percent since the 2001 report, which 

covered fiscal years 2001 through 2005, and the number of planned noise 

projects included in the 2011 NPIAS is nearly half what it was in 2001 

NPIAS.42 Despite the decreased number of planned projects, the 

anticipated costs for those projects rose to $2.1 billion, or roughly $425 

million per year.43

Table 1: Planned Airport Noise Projects Identified in the National Plan of Integrated 

Airport Systems since 2001

Table 1 shows the number and estimated costs of 

planned projects at airports as reported through the NPIAS since 2001.

NPIAS report

Airports with (and number 

of) noise projects

Planned noise projects 

estimated cost (in millions)

2001-2005 104 (369) $ 1,400

2005-2009 88 (283) 1,426

2007-2011 91 (178) 1,581

2009-2013 93 (187) 2,007

2011-2015 87 (188) 2,124

Source: GAO analysis of FAA data.

The nature of the projects in the most recent NPIAS has changed to focus 

more on projects designated to be in DNL 65-69 dB contours; the total 

 

41As a planning document, the NPIAS does not reflect the agency’s investment priorities. 

FAA prioritizes projects through its Airports Capital Improvement Plan (ACIP) which is 

compiled based on information prepared by regional offices. The project priority ranking 

included in the ACIP incorporates an airport’s size, the purpose of a project (such as 

insulating homes) and the specific types of efforts (such as insulating homes in the DNL 

65 dB contour).

42Since the 2007 NPIAS report, individual projects have been grouped together as part of 

a bigger multi-phased project that had previously been counted individually. The change 

may have contributed to apparent decreases in the number of projects. 

43These cost estimates are obtained from airport master plans and state system plans, 

and includes only AIP-eligible projects to be undertaken by airport sponsors. Cost 

estimates also don’t include contingency costs or normal price escalation.

Planned Noise Mitigation 

Project Demand
 

Page 29 GAO-12-890 Airport Noise Grants

estimated planned costs for mitigation inside DNL 70-74 dB contours has 

dropped, and there are no projects for land acquisition or noise insulation 

inside the DNL 75 dB contour. As discussed earlier, airports generally 

began with projects in the loudest contour, and the changes reflected in 

the NPIAS suggest that some airports have completed projects in those 

contours and are now focusing on projects in areas further away from the 

airport. In fact, the vast majority of noise-related projects identified in the 

2011 plan are focused on the further away DNL 65-69 dB contour—the 

contour with the lowest noise exposure that is considered significant 

under federal guidelines and still meets eligibility criteria.44

 

44Future demand for noise grants would change if the definition of significant airport noise 

were to change in the future. FAA, in collaboration with the Federal Interagency 

Committee on Airport Noise (FICAN) is currently researching whether DNL 65 dB remains 

the most appropriate measure for assessing airport noise exposure and, as a result of this 

research, may adopt a different definition of significant airport noise. If this criterion were 

lowered, then the number of projects eligible for AIP noise grants would likely increase. 

Our analysis did not assess possible future demand scenarios should this definition 

change. 

This shift of 

focus may partly explain why the most recent NPIAS has a higher total 

cost because contours further away from an airport tend to cover larger 

geographic areas and more homes, though increases in construction 

costs and other factors likely contribute as well. Figure 7 below shows the 

change in planned noise mitigation projects as reflected in the NPIAS.
 

Page 30 GAO-12-890 Airport Noise Grants

Figure 7: Planned Noise Project Estimates by Noise Contour as Reported in the 

National Plan of Integrated Airport Systems, 2001 through 2011

a

No NPIAS was prepared for 2003-2007 because of delays associated with September 11th terrorist 

attacks and other factors. FAA continued to make AIP noise grants during these years as usual.

The status of projects in existing NCPs is also an indicator of future noise 

grant demand and shows potentially lower future demand. Our analysis 

determined that 102 of 137 airports with NCPs more than 10 years old 

received no noise grants since fiscal year 2007 and that only 22 of these 

137 airports have noise mitigation projects in the 2011 NPIAS, an 

indication that some of these airports may have completed all of their AIP 

eligible noise mitigation projects. For several reasons, we could not fully 

assess the number of outstanding noise mitigation projects that are 

included in airports’ NCPs and that airports intend to seek noise grants for 

Noise Compatibility 

Programs
 

Page 31 GAO-12-890 Airport Noise Grants

in the future.45

Furthermore, airports have developed fewer new or updated NCPs in 

recent years, suggesting that future demand for noise grants may be 

waning as existing programs mature. As noted previously, since AIP 

noise grants were established in the early 1980s, FAA has approved 

NCPs for 234 airports and inclusion in an NCP is a prerequisite for AIP 

funding, with limited exceptions. About 85 percent (198 of 234) of the 

airports’ NCPs were approved more than a decade ago, and since 2007, 

only 14 new ones have been approved (see fig. 8).

However, some airports are nearing the end of their 

programs. For example, we were told by officials at 4 of the 7 airports that 

we reviewed that they anticipate completing their noise compatibility 

programs within about 3 years. At those airports without NCPs, some 

anticipate completing their public building insulation efforts in the near 

future. For example, officials from the Port Authority of New York and 

New Jersey indicated that they expect to complete the school insulation 

program around their airports within about 3 years.

 

45Although the NCP sets forth an airport’s plan to address noise, FAA does not centrally 

track the funding or completion status of those projects. In addition, because of the 

program’s voluntary nature, airports are not compelled to complete all projects listed in its 

NCP. An airport’s needs or priorities, for example, may change, which could result in 

some items being excluded from or added to its noise program. And even if an airport still 

intends to seek noise grants to fund listed projects, FAA is not obligated to fund projects 

via AIP. 
 

Page 32 GAO-12-890 Airport Noise Grants

Figure 8: FAA Approval of Noise Compatibility Programs, 1983 to 2011

Some communities around airports that are exposed to significant airport 

noise are not likely to receive residential noise insulation. Airports are free 

to choose not to perform residential noise insulation projects because 

developing an NCP—a necessary step for the airport to take to receive 

AIP funds for such projects—is voluntary. According to FAA and as would 

be expected, 30 years into a voluntary program, airports that are likely to 

pursue AIP-funded residential noise insulation programs have likely 

already at least begun to do so. Some of the busiest airports in highly 

populated areas have chosen not to complete an NCP. For example, 

officials from the Port Authority of New York and New Jersey indicated 

that they have not conducted Part 150 studies for any of the five airports 

under their jurisdiction because a residential noise insulation program 

would not alleviate noise exposure when people are outside their 

homes—they noted that noise complaints peak in the summer—and AIP’s 

grant-matching requirements would be financially prohibitive. To the 

extent that airports without NCPs continue not to participate in the Part 

150 program, the people living in areas significantly impacted by airport 
 

Page 33 GAO-12-890 Airport Noise Grants

noise may never receive the benefits of noise mitigation.46

Given the shrinkage of noise contours previously discussed, it is possible 

that if airports updated older NCPs and noise exposure maps, some 

noise projects in the current NPIAS—which reflects projects in NCPs—

would no longer meet grant eligibility criteria. These smaller noise 

contours would also reflect that the residential population within areas 

significantly impacted by noise has fallen dramatically. While there is no 

way to determine how many planned projects—and the costs of those 

projects—would no longer meet the grant eligibility criteria, the 2011 

NPIAS includes planned projects in areas designated as DNL 65-69 dB at 

61 airports. Eighteen of these 61 airports have over $770 million in 

projects even though their noise exposure maps are more than 10 years 

old; as noted previously, these maps are likely to overstate current noise 

exposure and funding to these projects could put federal investments at 

risk.

This population 

is about a third of the remaining population that FAA’s MAGENTA model 

estimated is exposed to significant airport noise. Specifically, in 2010, the 

model estimated 113,000 people (out of 323,000) lived near airports that 

had not developed an NCP, though this population is not monitored as 

part of FAA’s strategic goal and measurement approach discussed 

above.

47 Together, smaller contours and fewer noise impacted populations, 

if sustained, suggest that projects approved under updated NCPs could 

tend to be smaller in scale and scope.

Future changes in aircraft noise and the ongoing implementation of 

NextGen, could factor into future demand levels for AIP noise grants. FAA 

and the aviation industry expect aircraft noise levels to continue to fall 

with ongoing technological and operational advancements. Manufacturers 

continue to work to provide quieter engines for aircraft and to address 

noise produced by airframes. In addition, as NextGen is implemented, 

FAA is making an effort to incorporate changes that will not only improve 

the efficiency of the system, but also provide for quieter operations. FAA 

 

46FAA can provide grants directly to communities around medium and large hub airports 

where airports have not established an NCP, or where an NCP has not been updated in 

10 years. 49 USC § 47141. 

47Some of these 18 airports may have other noise exposure maps that are more recent 

because of, for example, an environmental assessment. FAA data would not include these 

maps. 

Technology and NextGen
 

Page 34 GAO-12-890 Airport Noise Grants

anticipates that there will be noise exposure reduction benefits resulting 

from the implementation of some operational changes, such as flight 

procedures. For example, new arrival procedures will involve less engine 

thrust, and thus result in quieter approaches. But even with these 

benefits, changes in flight paths will affect populations that had previously 

been subjected to less aircraft noise or less concentrated flight paths. 

This impact, however, would generally remain outside the DNL 65 dB 

contour and, unless the minimum eligible DNL were lowered, would not 

affect grant demand. FAA has not yet determined the extent of the impact 

of such operational changes on airport noise, and whether or how they 

might change noise contours or lower noise exposure around an airport. 

In contrast, the increases in air traffic predicted in the next decade, 

particularly at airports near large, densely populated urban areas, could 

result in recently contracted noise contours growing larger, which could 

offset, to some unknown degree, advancements in technology and 

operations. However, if noise contours reverse course and begin to 

expand, some of that expansion could be into areas that already have 

been remediated through previous noise mitigation efforts. In such cases, 

newly eligible noise mitigation projects would not result. Conversely, new 

incompatible land uses created by subsequent airport development or 

operational changes may be eligible for funding consideration.

In the future, more types of environmental projects will be competing for 

the same amount of AIP noise grant funds. The amount of funding 

available for noise grants is established by Congress. Recently, Congress 

has expanded the eligibility for noise set-aside funding to projects not 

directly related to noise, a change that has effectively decreased the 

funding available for noise programs in recent years. In addition, the 

Voluntary Airport Low Emission (VALE) program, which was designed to 

reduce ground sources of emissions at commercial service airports 

located in areas failing to meet or maintain EPA ambient air quality 

standards, became eligible for noise grant funding in fiscal year 2005.48

 

48GAO, Aviation and the Environment: Initial Voluntary Airport Low Emissions Program 

Projects Reduce Emissions and FAA Plans to Assess the Program’s Overall Performance 

as Participation Increases, 

Under the VALE program, FAA made 51 grants during fiscal years 2005 

to 2011 totaling $108.5 million at 30 airports. The 2011 NPIAS identifies 

plans for $87.9 million in VALE projects at 11 airports through fiscal year 

2015 (about 4 percent of the estimated cost of all AIP eligible noise 

GAO-09-37 (Washington, D.C.: Nov. 7, 2008).

Noise Mitigation Projects 

Will Compete with Other 

Projects for Noise Grants
 

Page 35 GAO-12-890 Airport Noise Grants

mitigation projects listed in the report). FAA airport district office officials, 

as well as airport officials we interviewed, indicated that VALE projects 

will continue to be pursued in the future. In addition to VALE, the 2012 

FAA reauthorization expanded eligibility for certain water projects at 

airports undertaken as a result of an environmental record of decision for 

an airport development project, such as a runway extension.49 FAA has 

not estimated future demand for VALE. And because the water project 

eligibility is new, no such projects appeared in the 2011 NPIAS report and 

FAA has yet to determine how these projects would be ranked against 

VALE and noise mitigation projects. Therefore, it is not clear how 

expanded eligibility for these other kinds of projects for AIP noise setaside grant funds may affect FAA’s ability to meet future noise grant 

demand.

Today, the number of people in the United States who are exposed to 

significant airport noise is considerably reduced from when FAA began 

providing AIP noise grants in the early 1980s. Overall, the program has 

benefited thousands of people over the years by mitigating airport noise—

one of the top environmental concern of airports. However, in the 

decades since the AIP noise grant program began, airports have 

completed numerous noise mitigation projects and technology has 

produced quieter aircraft and better operating procedures. Our review 

shows that, now and going forward, the need for noise grants may be 

lower than it was in the past. It is up to FAA to ensure that

• future noise grants are directed to the remaining projects that meet 

the grant eligibility criteria,

• the agency’s goal for addressing airport noise aligns with the current 

airport noise problem, and

• the measures used to assess progress accurately reflect FAA’s 

programmatic results.

As implemented, there is a risk that some federal investments in noise 

mitigation went to projects that may not have met existing eligibility 

criteria, and if not effectively addressed, this risk will continue in the 

 

49Pub. L. No. 112-95, §145, 126 Stat. 11, 30 (2012).

Conclusions 
 

Page 36 GAO-12-890 Airport Noise Grants

future. FAA has not uniformly enforced the accuracy of noise exposure 

maps and has inconsistently applied program criteria for interior noise 

assessments. This diminishes Congress’s and the public’s assurance that 

federal funding has been or will be spent appropriately and, to the extent 

that some misapplication of AIP grants to projects has occurred, creates 

the risk that more meritorious projects at other airports may not have 

been funded. It is encouraging that FAA issued guidance to more clearly 

articulate the program’s eligibility criteria and has called upon airports to 

review their noise programs to better ensure the eligibility of planned 

projects. If properly implemented and followed, this guidance should 

reduce the risk of federal investment in ineligible projects. However, since 

some of these problems have persisted despite previous FAA guidance, it 

is too soon to tell if FAA’s current actions will be successful.

Currently, FAA’s overall goal for its noise efforts is to reduce the 

population exposed to airport noise above DNL 65 dB to less than 

300,000 people by 2018 and FAA measures progress by estimating the 

residential population exposed to this noise level. However, there are 

shortcomings to this approach. First, FAA’s overall goal is disconnected 

from FAA’s primary tool to address noise—the AIP noise grants—

because it does not reflect the results of these grants. Beneficiaries of

noise insulation projects continue to reside or attend school in DNL 65 dB 

or louder areas even though the noise exposure has been mitigated for 

them. Second, approximately one-third of the estimated remaining 

population exposed to significant airport noise resides near airports that 

have yet to and may never establish an NCP. After 30 years, it appears 

unlikely that this population will ever be reached by the current program. 

FAA’s strategic goal and measures do not account for this population. To 

more effectively manage the program and target federal funds, goals and 

metrics should align with the nature and extent of the remaining airport 

noise problem. At present, however, the nature and extent of the 

remaining airport noise problem are ill-defined. Key steps to effectively 

address airport noise include

• understanding the nature and extent of the current problem,

• determining appropriate goals to address the problem,

• establishing metrics to measure progress, and

• using this information for decision making.
 

Page 37 GAO-12-890 Airport Noise Grants

Effective program management should increase the effectiveness of the 

current grant program and provide a more complete picture of noise grant 

results. Though a number of airports continue to have planned noise 

mitigation projects, after 30 years of funding noise grants, it is reasonable 

to question whether the program may remain relevant for only a limited 

period in the future or need to be reformed to better target emerging 

needs. Increased knowledge about the problem and the use of noise 

grants as a solution should help Congress and FAA chart the most 

appropriate course for the future of the AIP noise program.

To better ensure that federal investments effectively address the 

remaining airport noise problem and to more fully demonstrate the results 

of AIP noise grants, the Secretary of Transportation should direct FAA to 

take the following two actions:

• Establish a strategic noise reduction goal that aligns with the nature 

and extent of airport noise and targets the agency’s noise grant 

program.

• Establish performance measures to assess progress toward this goal 

that better demonstrate the results of the program and provide 

Congress and FAA’s program managers with information to gauge 

progress and make programmatic decisions.

We provided a draft of this report to the Department of Transportation 

(DOT) for its review and comment. DOT and FAA officials provided 

technical comments that we incorporated as appropriate. In addition, in 

emailed comments to us, DOT offered several observations on our report. 

First, DOT highlighted that the noise grant program is not the only means 

by which airport noise has been reduced, noting that other FAA initiatives 

and industry actions, especially those that led to improvements in aircraft 

engine technology are primarily responsible for airport noise reductions. 

We concur with this position but, as indicated in the report, the noise 

grant program is the largest FAA expenditure to address noise. Second, 

DOT officials stated their belief that noise grants only go to projects that 

meet eligibility criteria unless otherwise justified. However, as noted in our 

report, in light of the overall decline in airport noise, the age and potential 

inaccuracy of some noise exposure maps, and FAA’s inconsistent 

implementation of eligibility standards, we believe there is an increased 

risk for noise grants and have noted the limited circumstances under 

Recommendation for 

Executive Action

Agency Comments 

and Our Evaluation
 

Page 38 GAO-12-890 Airport Noise Grants

which grants can be made to projects that don’t meet these criteria. FAA’s 

recent issuance of guidance clarifying eligibility criteria is commendable 

and needed because, if properly implemented, it will address this risk. 

Finally, DOT noted that FAA sets annual beneficiary targets for noise 

grants, tracks progress toward these targets, and reports these results to 

Congress. We acknowledged these actions in our report, but these 

targets, results, and reporting are not linked to FAA’s strategic noise goal 

and measurement approach nor are they included in FAA’s reporting on 

progress toward that strategic goal. Without a linkage between the results 

of FAA’s most costly program to address noise and FAA’s strategic goal 

for addressing noise, Congress, FAA, and the taxpayers do not have 

sufficient information on the value of these continued investments.

FAA reviewed our recommendations and agreed to consider them for 

action.

We are sending copies of this report to the Secretary of the Department 

of Transportation, the Administrator of the Federal Aviation 

Administration, and appropriate congressional committees. This report is 

also available at no charge on the GAO website at http://www.gao.gov.

If you or your staff have any questions about this report, please contact 

me at (202) 512-2834 or dillinghamg@gao.gov. Contact points for our 

Offices of Congressional Relations and Public Affairs may be found on 

the last page of this report. GAO staff who made major contributions to 

this report are listed in appendix II.

Gerald L. Dillingham, Ph.D.

Director, Physical Infrastructure Issues
Appendix I: Objectives, Scope, and 

Methodology

Page 39 GAO-12-890 Airport Noise Grants

This report addresses the following objectives: (1) how airports’ noise 

exposure has changed since federal noise grants were first funded, (2) 

how Airport Improvement Program (AIP) grants have been used by 

airports to mitigate noise and what have these grants achieved, and (3) 

the likely future demand for AIP noise set-aside grants. 

To describe how airport noise exposure has changed over time, we 

reviewed available literature and met with industry organizations. For the 

purposes of this report, we used the currently accepted definition of 

significant airport noise (e.g., DNL 65+ dB). We interviewed officials from 

the Federal Aviation Administration’s (FAA) Office of Airports and the 

Office of Policy, International Affairs and Environment at FAA 

Headquarters, and at 4 Airport District Offices in 3 of 7 FAA regions. We 

also performed a Geographic Information Systems (GIS) analysis of noise 

contours at selected airports to illustrate the changes to areas exposed to 

airport noise over time. To assess how the population exposed to noise 

has changed over time, we obtained information from FAA’s MAGENTA 

noise model. We did not independently assess the MAGENTA model 

itself. FAA uses this model to estimate the population exposed to 

significant airport noise. The MAGENTA estimates for noise exposure are 

broadly used and generally considered accurate for the purposes 

intended.

To assess how AIP grants have been used for noise project planning and 

implementation, we obtained and analyzed data in FAA’s System of 

Airport Reporting (SOAR). This database includes detailed information 

about AIP grants, Passenger Facility Change (PFC) approvals, project 

types, and other airport information. We assessed the reliability of SOAR 

data by (1) performing electronic testing of required data elements, (2) 

reviewing existing information about the data and the systems that 

produced them, and (3) interviewing agency officials knowledgeable 

about the data. We determined that the data were sufficiently reliable for 

the purposes of this report. We met with sponsors of 7 airports in three 

regions to discuss the development and implementation of their noise 

compatibility programs. These airports were judgmentally selected to 

provide information from airports of different sizes, different parts of the 

country, and at different points in implementing their noise projects. 

Information obtained from these airports is for illustrative purposes only, 

and cannot be generalized for all airports. To understand how the results 

of AIP noise grants have contributed to FAA’s progress towards achieving 

Appendix I: Objectives, Scope, and 

Methodology 
Appendix I: Objectives, Scope, and 

Methodology

Page 40 GAO-12-890 Airport Noise Grants

its strategic noise goal, we assessed FAA’s use of its MAGENTA noise 

model compared to GAO criteria.1

To assess future demand for AIP noise grants, we reviewed planned 

projects in the National Plan for Integrated Airport Systems (NPIAS), 

FAA’s primary tool for identifying potential airport capital projects. The 

NPIAS data is part of FAA’s SOAR reporting system. We also obtained 

information about the dates of airports’ Noise Compatibility Programs 

(NCPs) and noise exposure maps from the Office of Airports at FAA 

Headquarters. For the purposes of this report, we used the currently 

accepted definition of significant airport noise (e.g., DNL 65+ dB)—as 

does the NPIAS—to identify potential future noise projects. The results of 

our analysis of future demand for noise grants would change if the 

definition of significant airport noise changes in the future. To understand 

the implementation and future of airport noise programs, we reviewed 

noise programs at the 7 airports indicated above and discussed them with 

the 4 Airports District Offices which oversee those airports.

We conducted this performance audit from October 2011 through 

September 2012 in accordance with generally accepted government 

auditing standards. Those standards require that we plan and perform the 

audit to obtain sufficient, appropriate evidence to provide a reasonable 

basis for our findings and conclusions based on our audit objectives. We 

believe that the evidence obtained provides a reasonable basis for our 

findings and conclusions based on our audit objectives.

 

1

GAO, Executive Guide: Effectively Implementing the Government Performance and 

Results Act, GAO/GGD-96-118 (Washington, D.C.: June 1996). 
Appendix II: GAO Contact and Staff 

Acknowledgments

Page 41 GAO-12-890 Airport Noise Grants

Gerald L. Dillingham, Ph.D. (202) 512-2834 or dillinghamg@gao.gov

In addition to the individual named above Paul Aussendorf (Assistant 

Director), Amy Abramowitz, Hiwotte Amare, Elizabeth Curda, Jeff Heit, 

Dave Hooper, Christopher Jones, Delwen Jones, John Mingus, SaraAnn 

Moessbauer, Josh Ormond, and John Stambaugh made significant 

contributions to this report.

Appendix II: GAO Contact and Staff 

Acknowledgments 

GAO Contact

Staff 

Acknowledgments 

540229
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