Aviation and the Environment: FAA's Role in Major Airport Noise Programs
Published: 2000-04-28T00:00:00

Fast Facts:

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

section_title: Letter
paragraphs: In response to your request, this report discusses issues related to airport noise, describing, in  particular, (1) the eligibility of noise reduction and mitigation projects for federally authorized  funding, (2) methods for measuring airport noise, (3) aircraft noise standards for civil subsonic  turbojets, and (4) the Federal Aviation Administration’s Land Use Planing Initiative, which was  designed to facilitate state and local land use planning for areas near airports.
As agreed with your offices, unless you publicly announce its contents earlier, we plan no further  distribution of this report until 14 days after the date of this letter. At that time, we will send copies to  the appropriate congressional committees; the Honorable Rodney E. Slater, Secretary of  Transportation; and the Honorable Jane F. Garvey, Administrator, Federal Aviation Administration. We  will also make copies available to other interested parties upon request.
If you or your staff have any questions about this report, please contact me or Belva Martin, Assistant  Director, at (202) 512-2834. Major contributors to this report are listed in appendix X.
subsections: section_title: Introduction
paragraphs: Since the introduction of turbojet aircraft in the late 1950s for commercial  passenger service, airport-related noise has generated controversy with  many surrounding communities and emerged as a constraint on airport  development. Airport-related noise emanates primarily from the takeoff  and landing of aircraft, but engine maintenance and the taxiing of aircraft  on runways are some of the other activities that also contribute to airport- related noise. New technology has been making aircraft quieter, and since  1969 the Federal Aviation Administration (FAA) has been limiting the noise  that various aircraft are allowed to make. As a result, FAA estimates that  the population exposed to very high noise levels will have declined from  7 million in 1975 to an estimated 600,000 in 2000. But in spite of the recent  transition to quieter aircraft, expected growth in air traffic may result in  little or no net reduction in overall noise levels generated by individual  airports. Furthermore, concerns about airport-related noise may impede  the development of any needed additional capacity in the national network  of airports.
The Congress has recognized the importance of developing a safe and  efficient national airport system that meets the nation’s present and future  aviation needs. As a result, federally authorized investment in a national  airport system, including noise reduction projects, has totaled about  $3 billion a year in recent years. FAA has primary responsibility for  implementing federal programs addressing noise issues associated with  civilian airports.
subsections: section_title: The Federal Role in Addressing Airport- Related Noise
paragraphs: In order to facilitate the development of a safe and efficient national airport  system, FAA undertakes several activities that help airports and  communities reduce airport-related noise or mitigate its effects. FAA must  consult with the Environmental Protection Agency regarding some of its  responsibilities. FAA’s activities focus on three areas: (1) reducing aircraft- generated noise at its source—the aircraft; (2) changing an airport’s use of  its runways and/or implementing different flight operations; and  (3) mitigating the effects of existing noise levels on surrounding  communities.
subsections: section_title: Reducing Airport-Related Noise at Its Source
paragraphs: Airport-related noise can be lowered by reducing the noise that aircraft  emit when they take off from and land at airports. New technology allows  aircraft manufacturers to design and construct quieter aircraft. For aircraft  already in service, noise levels can be reduced by (1) installing quieter  engines, (2) installing equipment that reduces the noise of existing engines,  and (3) modifying aircraft use and operations in ways that reduce aircraft- generated noise.
FAA has actively engaged in efforts to reduce aircraft noise since the 1960s.  The agency sets the noise standards aircraft must meet to be certified as  airworthy and establishes the regulations that govern the operation of  those aircraft at U.S. airports. The Federal Aviation Act of 1958, as  amended in 1968, gave FAA the authority to regulate aircraft design and  equipment in order to reduce noise. Pursuant to that act, FAA issued  regulations in 1969 that established noise standards for new designs of civil  subsonic turbojet aircraft. According to an aircraft design expert, the  purpose of those noise standards was to ensure that the best available  noise reduction technology was used in new aircraft designs.
Initially, these regulations prescribed noise standards that applied only to  new types or designs of turbojet aircraft (as well as certain propeller  aircraft). In 1973, FAA amended its regulations to apply the noise standards  to all newly manufactured aircraft, whether or not the aircraft design was  new. In 1977, additional amendments established lower noise standards for  all new aircraft, as well as the concept of noise “stages.” Aircraft meeting  the original 1969 standards were categorized as “stage 2” aircraft; those  meeting the more stringent 1977 standards were categorized as “stage 3”  aircraft; and aircraft meeting neither standard were categorized as “stage 1”  aircraft.
In addition to establishing noise standards, FAA controls aircraft noise by  regulating aircraft operations. In 1976, FAA amended its regulations to  prohibit all certificated stage 1 subsonic turbojet aircraft weighing more  than 75,000 pounds from flying into or out of U.S. airports after January 1,  1985, unless their engines had been modified or replaced to enable them to  meet the stage 2 or stage 3 noise standards. However, the Aviation Safety  and Noise Abatement Act of 1979 directed FAA to grant exemptions from  compliance until January 1, 1988, to turbojet aircraft with two engines and  fewer than 100 passenger seats.
In 1990, the Airport Noise and Capacity Act required civil subsonic turbojet  aircraft weighing more than 75,000 pounds to comply with stage 3 noise  standards by December 31, 1999, or be retired from service. To meet this  requirement, the engines on stage 2 aircraft could be modified or replaced.
In addition to regulating aircraft-generated noise, FAA supports aviation  research related to noise. In particular, FAA is working with the National  Aeronautics and Space Administration to develop new technology to  reduce aircraft noise.
section_title: Changing an Airport’s Use or Operations
paragraphs: By changing use and/or operations, airports can reduce airport-related  noise or mitigate its effects. For example, an airport can restrict noisy  aircraft maintenance activities to areas where noise barriers can muffle the  sound. Aircraft arrival and departure flight paths, as well as runway use,  can be changed to minimize flights over densely populated areas. Airports  can also mitigate noise impacts by seeking FAA approval to restrict certain  aircraft to takeoffs and landings during the day, when their impact on  nearby communities is considered less than during the night.
FAA is involved in many of these activities. For example, FAA must  approve any restriction on an aircraft’s access to an airport or on allowable  noise levels if the restriction involves stage 3 aircraft or is beyond those  imposed by federal regulations. Thus, if an airport wants to restrict any  stage 3 aircraft to daytime operations, it must obtain FAA’s approval. FAA  must also approve and implement changes in flight paths. Furthermore,  FAA administers airport development funding programs, which can finance  the construction of runways and taxiways that enable aircraft to use  different takeoff and landing routes to minimize flights traveling over  densely populated areas.
section_title: Mitigating the Effects of Airport-Related Noise
paragraphs: Mitigation activities can reduce the impact of airport-related noise on the  communities surrounding an airport. For example, buildings in nearby  communities can be soundproofed and building codes can be changed to  require improved sound suppression construction; noise barriers can be  constructed; and airports can acquire land to prevent uses that are  incompatible with the prevailing noise exposure levels. Communities can  also exercise their authority over land use planning to help prevent the  future development of land for activities that are noise-sensitive—such as  those occurring in residences, schools, churches, and hospitals—in areas  exposed to high noise levels.
FAA supports mitigation efforts through two programs that provide  federally authorized funds for airport projects that mitigate the effects of  noise, and one program that encourages airports to identify and address  the noise impacts of their airports on nearby communities.
subsections: section_title: FAA Administers Two Programs That Fund Noise Mitigation Projects
paragraphs: The Airport Improvement Program (AIP) and the Passenger Facility Charge  (PFC) program provide federally authorized funding that, among other  purposes, can be used to help mitigate the effects of airport-related noise.  The AIP, established by the Airport and Airway Improvement Act of 1982,  provides federal grants—funded by congressional appropriations from the  Airport and Airway Trust Fund—for developing airport infrastructure,  including projects that reduce airport-related noise or mitigate its effects.  Airports must provide a “matching share” for AIP-funded projects, ranging  from 10 percent to 25 percent of a project’s total cost, depending on the  type of project and the size of the airport.
Two categories of AIP grants are available—apportionment and  discretionary. Apportionment funds are distributed by a statutory formula  to commercial service airports according to the number of passengers  served and the volume of cargo moved, and to the states according to a  percentage of the total amount of the appropriated funds. Discretionary  funds—for the most part, those amounts remaining after apportionment  funds are allotted and certain other amounts are “set aside” for special  categories, including noise-related projects—can generally be awarded for  eligible projects at any eligible airport, including general aviation airports,  which do not receive apportionment funds.
Only airports included in FAA’s National Plan of Integrated Airport Systems  are eligible for AIP grants. The National Plan of Integrated Airport Systems  identifies those U.S. airports that constitute the national airport system,  which is designed to ensure that every part of the country has an effective  aviation infrastructure. There are 529 commercial service airports—those  that receive apportionment funds—and 2,815 general aviation airports (for  a total of 3,344 airports) in the current national plan. Furthermore, all  projects funded with AIP funds—whether apportionment or  discretionary—must be approved by FAA. However, FAA will not approve  any grant for any kind of project without written assurances that the  airport will take appropriate action, to the extent possible, to restrict the  use of land near the airport to uses compatible with airport operations.
The AIP funds noise mitigation projects in two ways. First, a specified  portion of AIP appropriations is “set aside” by statute specifically for  projects that address airport-related noise levels and their effects. Only  projects relating to noise may be funded from this set-aside. Table 1  identifies the portions of AIP funds that have historically been set aside for  noise. In addition to being eligible for these set-aside funds, projects  addressing airport-related noise may compete with other airport  development projects for other AIP grants.
The second program providing federally authorized funds for mitigating  airport-related noise—the PFC program—is a voluntary program that  enables airports to impose fees on boarding passengers—known as  passenger facility charges—and retain the money for airport infrastructure  projects, including noise reduction. Under this program, authorized by the  Aviation Safety and Capacity Expansion Act of 1990, commercial service  airports may charge boarding passengers a $1, $2, or $3 fee. Airports are  not required to impose the fee, but airports wishing to participate in the  program must seek FAA’s approval both to levy the fee and to use the  revenues for particular development projects. Airlines collect the fees from  passengers and transmit them directly to the appropriate airports. FAA  officials told us that as long as a project is eligible, meets one of the  statutory objectives, and is adequately justified, they do not have the  authority to reject an airport’s proposal for the collection or use of  passenger facility charges.
section_title: FAA Defines Land Use Compatibility and Administers an Airport Noise Compatibility Planning Program to Facilitate Noise Mitigation
paragraphs: Although the federal government has no jurisdiction over land use  decisions (that authority lies with state and local governments), FAA can  facilitate compatible land use planning at the state and local level. The  Aviation Safety and Noise Abatement Act of 1979 directed FAA to define  land uses that it considers compatible or incompatible with the various  noise levels that nearby communities are exposed to. The act also directed  FAA to administer a new program that encourages airports to develop  maps identifying areas in nearby communities where land uses are  considered to be incompatible. The program also encourages airports to  develop individual airport noise compatibility programs that include those  maps and the projects that have been implemented, or planned, to reduce  any existing or potential incompatible land uses identified. The act also  requires FAA to approve an airport’s noise compatibility program as long  as the program does not place an unreasonable burden on interstate or foreign is reasonably consistent with achieving the goal of reducing  incompatible land uses and preventing the introduction of new  incompatible land uses, and authorizes needed revisions to the program’s planned projects when  noise exposure maps are updated.
Programs, except as they relate to flight procedures, are automatically  approved if FAA has not acted within 180 days after receipt of the proposed  program. Once an airport’s program is approved, the airport can apply for  AIP grants to fund the types of projects included in the program that are  eligible for federal grants. Through fiscal year 1999, 195 airports had FAA- approved noise compatibility programs, while 212 had approved noise  exposure maps. Appendix I describes the process for obtaining FAA  approval of the maps and airports’ noise compatibility programs.
section_title: Objectives, Scope, and Methodology
paragraphs: The Subcommittee on Aviation, House Committee on Transportation and  Infrastructure, and several Members of the House of Representatives asked  us to address four sets of questions about federal programs for airport  development and the alleviation of airport-related noise:
What kinds of projects that reduce airport-related noise or mitigate its  effects are eligible for federally authorized funding, how do FAA’s  selection criteria affect which projects are funded, and to what types of  projects have the funds been historically distributed?
How do major methods for measuring the impact of airport-related  noise compare with each other, and what method has FAA selected?
What aircraft noise standards apply to civil subsonic turbojets, and why  are some civil subsonic jets not required to comply with these and  earlier noise standards?
What actions has FAA announced under its Land Use Planning Initiative,  what is the status of their implementation, and what issues has the  Initiative raised?
To address the first set of questions—on the eligibility of noise-related  projects for federally authorized funding—we (1) reviewed the statutory  provisions and FAA’s regulations, policies, and procedures for funding  projects under the AIP and the PFC program to identify project eligibility;  (2) reviewed the statutory requirements for airport-related noise  compatibility programs, as well as FAA’s regulations and processes for  implementing those requirements; (3) obtained FAA’s data on federal grants  awarded for noise-related projects and passenger facility charges approved  for noise-related projects to identify the types of projects and the total  project funding by fiscal year for each type of noise-related project. We also  interviewed officials from FAA headquarters in Washington, D.C.; the  Airports Council International-North America; the Air Transport  Association; and the National Association of State Aviation Officials; as  well as other experts on these issues. In 1999, we independently validated  the PFC project database and found it to be very reliable (a 0.3-percent  error rate). We did not independently review the validity of the grant  program database, but it is the only database for that information, and we  have used data from it extensively during the conduct of several reviews  that have looked at various aspects of the grant program.
To address the second set of questions—on comparing methods that  measure airport-related noise—we (1) discussed noise measurement  methods with FAA, airport officials, the Airports Council International- North America, the Air Transport Association, the National Association of  State Aviation Officials, and the Federal Interagency Committee on Noise,  as well as other aviation experts, to identify the kinds of methods being  used to measure noise levels and the strengths and weaknesses of these  methods; (2) reviewed the major noise measurement methods, as well as  written descriptions and analyses of them, to determine how each method  measured airport-related noise; and (3) identified the statutory  requirements for FAA to select a method for environmental impact and  land use analyses and the method that FAA chose. To compare and  illustrate the kinds of information produced by each method, we designed a  model airport and test scenarios; FAA then conducted noise measurements  for us for the test scenarios using its Integrated Noise Model, its  computerized program for applying noise measurement methods. The  methods that were compared are the Maximum Sound Level and the Sound  Exposure Levels methods used to measure the noise of a single event, and  the Equivalent Sound Level, the Day-Night Sound Level, the Community  Noise Equivalent Level, and the Time-Above methods used to measure the  levels of noise that nearby communities are exposed to. We discussed the  reliability of the Integrated Noise Model with FAA officials and found that  they had used appropriate methods—including an independent  assessment—to ensure the model’s reliability for measuring noise  experienced at certain distances from the source.
To address the third set of questions—on aircraft noise standards—we  reviewed the statutes, policies, and regulations governing noise levels for  civil subsonic jets, and we discussed these statutes, policies, and  regulations with FAA officials, representatives of the General Aviation  Manufacturers Association, the National Business Aviation Association,  and the Regional Aviation Association, and other experts. Through  interviews and document review, we identified activities under way in the  United States, Europe, and the International Civil Aviation Organization to  address the issue of a new level of more stringent aircraft noise  standards—commonly referred to as “stage 4” noise standards. To  determine the number of aircraft weighing less than 75,000 pounds that  were not required to meet FAA’s most recent aircraft noise standards, we  determined, from FAA’s list of aircraft in the United States that it has  certified as airworthy, the number of civil subsonic jets weighing  75,000 pounds or less. To identify the noise standard that those aircraft met,  we reviewed FAA documentation identifying noise stages for certain  aircraft, Jane’s All The World’s Aircraft, and aircraft manufacturers’  specifications for aircraft types. While we did not test the validity of FAA’s  aircraft database, it is the only source for the information we sought.
Finally, to address the fourth set of questions—on FAA’s Land Use Planning  Initiative—we identified the overall objective of the Initiative, the initial  short-term actions that FAA announced in May 1999, and the status of FAA’s  implementation of those actions. To determine if any issues were raised by  the Initiative, we reviewed and analyzed the public comments submitted in  response to FAA’s request for comments and suggestions on its land use  planning effort under the Initiative, as well as published comments  analyzing the Initiative. We also interviewed officials at FAA, the Airports  Council International-North America, the National Association of State  Aviation Officials, and airport and community officials for Dulles  International Airport (a large hub without a completed noise compatibility  program) and Manassas Regional Airport (a general aviation airport with  an approved noise compatibility program), both in Virginia, and other  aviation experts to obtain their views.
A panel of five experts reviewed the design and methodology for our work.  These experts were selected because of their knowledge about aviation  and airport-related noise issues and FAA’s noise programs. A list of the  panel members appears in appendix IX.
We conducted our review from July 1999 through April 2000 in accordance  with generally accepted government auditing standards.
section_title: Project Eligibility for Federally Authorized Funding Is Broad, but Other Factors Affect Project Selection
paragraphs: Most types of projects to reduce airport-related noise or mitigate its effects  on nearby communities are eligible for federally authorized funding  through the Airport Improvement Program (AIP) and the Passenger  Facility Charge (PFC) program.  Under the AIP, however, statutes require  that, with a few exceptions, projects be part of an airport’s noise  compatibility program.  Once an airport applies for AIP funding, FAA sets  priorities for projects using two types of project selection criteria before  awarding the grants.  The PFC program is a more flexible funding source  than the AIP, in part because projects do not have to be part of an approved  noise compatibility program and because airports set their own priorities,  subject to FAA approval.  Since the programs began, the majority of funds  have been used to acquire land and soundproof buildings.
subsections: section_title: Most Types of Projects Are Eligible for AIP, but They Generally Must Be Part of an FAA- Approved Airport Noise Compatibility Program
paragraphs: The types of noise-related projects eligible for AIP funding include such  efforts as developing information to prepare planning and noise  compatibility program documents, acquiring land, acquiring air rights or  other easements, purchasing noise-monitoring equipment, constructing  noise barriers, and soundproofing buildings.  The construction or  expansion of runways and taxiways, which can reduce noise levels  affecting some communities by enabling flights to avoid densely populated  areas, is also eligible for AIP funding.
There are some statutory restrictions on eligibility.  AIP grants may not be  approved for land purchases unless the airport provides written assurance  that the following conditions will be met: the land will be sold at fair market value as soon as possible once it is no  longer needed to help mitigate the effects of noise; an airport will retain a legal interest in the land when it is sold in order  to ensure that its use remains compatible; and the government’s share of the cost of purchasing the land will be  reimbursed when the land is sold.
In addition, federal appropriations law prohibits the use of AIP funds for  studies, maps, or environmental impact analyses needed to implement  flight procedure changes made to reduce noise.  These costs are paid for by  other appropriated funds for air traffic control.
In addition to these statutory restrictions, FAA policy prohibits using AIP  funds for remedial noise mitigation—such as soundproofing buildings—for  buildings that were known to be  incompatible with prevailing noise  exposure levels before they were built.
To qualify for AIP funds that are set aside for noise-related projects, an  airport must have an FAA-approved noise compatibility program that  includes the projects the airport wants funded, except that projects to  insulate public buildings used primarily for educational or medical  purposes can be funded even though an airport does not have such a  program.  Nevertheless, FAA approval of an airport’s program does not  guarantee that the projects in it will receive AIP noise set-aside funding  because an airport must apply for AIP funding separately once its program  is approved.
In addition, AIP funds may pay for projects that mitigate the noise impact  of other airport development projects—such as the construction of a new  runway—even if the noise-related projects are not included in an approved  noise compatibility program.  The airport, however, would have to use its  AIP apportionment funds for those projects or the projects would have to  compete with other airport development projects for AIP discretionary  funds.
section_title: Selection Criteria Influence Which Eligible Projects Receive AIP Funding
paragraphs: In deciding which eligible projects to fund, FAA sets priorities using (1) its  guidance on land use compatibility and (2) a national priority system that  comparatively ranks all projects eligible for AIP funding.  When awarding  AIP funds for projects included in an airport’s noise compatibility program,  FAA gives priority to projects located in areas where noise exposure levels  are 65 decibels or higher (when measured under a method that assigns  greater weight to flights occurring between 10 p.m. and 7 a.m.).  Projects  are eligible for funding in areas with lower noise exposure levels.  However,  according to FAA officials, nearly all of the AIP funds set aside for noise- related projects in the past have been awarded for projects where  incompatible land uses occur in areas exposed to noise levels of  65 decibels or higher under FAA’s chosen method for measuring community  exposure to airport-related noise.
FAA also sets priorities for AIP-eligible projects through a national priority  system that comparatively ranks all projects, including noise-related  projects, in order to identify those projects that most warrant funding.   First, FAA applies a formula that assigns projects a numerical score from  0 to 100—the higher the score, the higher the priority.  The formula ranks  projects by assigning points for each of four factors: the project’s purpose (for example, safety, security, capacity, planning,  reconstruction), with, safety and security projects, for example,  receiving more points—higher priority—than projects to develop  airport capacity; the size of the airport (for example, large, medium, or small commercial  service airports), with projects at larger airports receiving more points  than projects at smaller airports; the project’s component (for example, apron, equipment, building,  financing), with runway projects, for example, receiving more points  than projects for equipment or taxiways; and the project type (for example, noise, by noise exposure level; airport  access; construction; de-icing facility; aircraft rescue; or fire-fighting  vehicle), with noise-related projects in areas exposed to high noise  levels, for example, receiving more points than noise-related projects in  areas with lower noise exposure levels.
FAA officials then consider other factors—such as benefit-cost analysis,  risk assessment, environmental issues, regional priorities, state and  metropolitan system plans, airport growth, and market forces—in  determining the final ranking of a project.  FAA officials have discretion  over the relative importance of the formula and other factors in deciding  the final ranking of projects.
According to an FAA official, projects competing for AIP funds set aside for  noise-related projects are ranked on the basis of project type and airport  size because the values of the other two factors in the formula are the same  for all noise-related projects.  As a result, projects in areas with higher  noise exposure levels and for larger airports will score higher under the  formula than projects in areas with lower noise exposure levels and for  smaller airports.  When noise-related projects compete for other AIP  discretionary funds, however, all four factors in the formula contribute to  determining the project’s comparative ranking.
Even if an airport’s project ranks relatively high, however, it may not be  funded in a given year.  According to an FAA official, for the past few years  FAA has applied an administrative cap that limits the amount of AIP  funding awarded to any single airport in one year for noise-related projects.   The limit is $5 million for projects included in an airport’s noise  compatibility program and $3 million for insulating public buildings used  primarily for educational or medical purposes (whether or not the airport  participates in the noise compatibility program).  According to the FAA  official, FAA imposes the limits when the demand for AIP funds set aside  specifically for noise-related projects exceeds the amount of AIP funds  available.  The limits are intended to ensure that all airports that need  funding for noise-related projects have access to AIP funds.  The FAA  official explained that the agency has exceeded the limit for an airport  when sufficient funds were available to meet all demand and the airport  was able to document its ability to spend more in that year.  The official  also said that each year FAA reevaluates whether the limits are needed; if  the total cost of the noise projects submitted for funding substantially  exceed the money available, the limits will generally remain in effect.
section_title: The PFC Program Can Fund Some Project Costs Ineligible for AIP Grants
paragraphs: The statutes define eligible types of noise-related projects under the PFC  program as anything eligible for AIP funding.  Unlike most projects funded  with AIP grants set aside for noise-related projects, however, PFC projects  do not have to be part of an FAA-approved noise compatibility program.   Nevertheless, according to FAA officials, FAA requires airports to  demonstrate that the projects will provide noise reduction or mitigation  and would qualify for inclusion in a noise compatibility program.  In  addition, unlike AIP funds, PFC funds may be used to pay the financing  costs for an approved project and the nonfederal share of projects funded  with AIP grants.  Airports can set their own priorities, subject to FAA  approval, regarding which noise-related projects to fund through the PFC  program.
section_title: Land Acquisition and Soundproofing Projects Receive the Majority of AIP and PFC Noise-Related Funding
paragraphs: More than 75 percent of all AIP funds and over 50 percent of all PFC funds  spent on noise reduction or mitigation have been used to acquire land and  to soundproof buildings.  This is generally true for both large and small  airports.  In this report, “large” airports are those airports categorized in  FAA’s National Plan for Integrated Airport Systems—those airports eligible  for AIP grants—as large and medium hub airports.  “Small” airports are  those categorized as small hub, nonhub, other commercial service, and  general aviation airports.
subsections: section_title: AIP Projects
paragraphs: Of the nearly $24 billion in AIP grants awarded for fiscal years 1982  through 1999, over $2.7 billion, or 11.5 percent, were for noise-related  projects.  Of this amount, $1.4 billion (over 50 percent) was used to acquire  land for noise mitigation purposes, and $673 million (nearly 25 percent)  was used to soundproof buildings.  Figure 2 shows the distribution of total  AIP funds for noise-related projects by project type for fiscal years 1982  through 1999.  Appendix III provides AIP funding data for noise-related  projects for each fiscal year, from 1982 through 1999, by project type.
About $2.1 billion of the $2.7 billion in AIP noise-related grants went to  large airports and about $582 million went to small airports for noise- related projects.  As figure 3 shows, both large and small airports targeted  their AIP grants for land acquisition and soundproofing buildings.
section_title: PFC Projects
paragraphs: For fiscal years 1992 through 1999, FAA approved the collection of nearly  $24 billion in passenger facility charges, with over $1.6 billion, or  6.9 percent, approved for noise-related projects.  About $755 million  (46 percent) of this funding has been approved for projects that will require  multiple phases to complete.  These projects consist of one or more  different types of projects that are approved together—usually  combinations of soundproofing and land acquisition, according to an FAA  official.  About $481 million (just over 29 percent) has been approved for  projects to soundproof buildings, while $378 million (23 percent) has been  approved for projects to acquire land.  Figure 4 shows the distribution of  noise-related projects approved for fiscal years 1992 through 1999, by  project type.  Appendix IV provides data on the amount of PFC funds  approved in each fiscal year, from 1992 through 1999, by project type.
Of the $1.6 billion in PFC funds approved for noise-related projects, nearly  all was approved for large airports, while about $46 million was approved  for small airports.  FAA has approved about the same portion of multiple- phase projects for large and small airports at 46 percent ($735 million) and  45 percent ($21 million) respectively.  However, large and small airports  differ in their use of PFC funds for other types of projects.  For example,  large airports had a much larger portion of their funds approved for  soundproofing buildings.  Figure 5 illustrates the funding pattern by project  type for large and small airports.
section_title: Noise Measurement Methods Provide Different Kinds of Information
paragraphs: Methods for measuring airport-related noise assess noise either from a  single takeoff or landing or from the cumulative average noise that nearby  communities are exposed to over time.  Required by law to select a single  method for measuring the impact of airport-related noise on communities,  FAA chose a method that measures community exposure levels and that  gives greater weight to the impact of flights occurring during the nighttime.   While subsequent studies have confirmed that this method best meets the  statutory requirement that FAA establish a single system for determining  the exposure of people to airport-related noise, a federal interagency  committee addressing airport-related noise issues found that supplemental  information, such as measures of noise from a single aircraft takeoff or  landing, is also useful in explaining the noise that people are likely to hear.   In addition, experts and community groups believe FAA’s chosen method  provides insufficient information because it does not effectively convey to  people what they can actually expect to hear in any given area.
subsections: section_title: Measuring Sound and Its Effects
paragraphs: To understand the methods used to measure noise, it is necessary to have  some understanding of how sound is measured and how it affects humans.   Some basic concepts include (1) sound waves and their measurement in  decibels, (2) human ability to hear the entire range of sounds made, and  (3) noise as a source of interference in people’s activities.
First, sound radiates in “waves” from its source and decreases in loudness  the further the listener is from the source.  As sound radiates from its  source, it forms a sphere of sound energy.  Sound waves exert sound  pressure, commonly called a “sound level” or “noise level,” that is  measured in decibels. The higher the number of decibels, the louder the  sound appears to someone hearing it.  But because decibel levels are  measured logarithmically, an increase of only 10 decibels—for example,  from 50 decibels to 60 decibels—doubles the loudness that people believe  they hear.  Continuing the increase from 60 to 70 decibels would again  double the perceived loudness of the sound.  Which sounds are considered  to be noise, however, is subjective.
In terms of aircraft noise, sound levels generated by takeoffs or landings  vary depending on several factors, particularly the aircraft’s weight and the  number of engines.  While airport-related noise levels decrease quickly  with distance from an airport, the accuracy of noise measurement also  decreases because it is more difficult to distinguish between airport-related  noise and other noise in the environment.
Second, while the human ear can hear a broad range of sounds, it cannot  hear all sounds.  Sounds with very low pitches (low frequencies) and  sounds with extremely high pitches (high frequencies) are generally  outside the hearing range of humans.  Because of this, environmental noise  is usually measured in “A-weighted” decibels.  The A-weighted decibel unit  focuses on those sounds the human ear hears most clearly and  deemphasizes those sounds that humans generally do not hear as clearly.   Table 2 illustrates the typical sound levels of some common events.
Dishwasher on rinse cycle at 10 feet Bird calls (outdoors)
Finally, the impact of noise on communities is usually analyzed or  described in terms of the extent to which it annoys people.  Annoyance  refers to the degree to which noise interferes with activities such as sleep,  relaxation, speech, television, school, and business operations.  While it is  difficult to predict how an individual might respond to, or be affected by,  various sounds or noises, some studies indicate that it is possible to  estimate what proportion of a population group will be “highly annoyed” by  various sound levels created by transportation activities.  The findings of a  1978 study that related transportation noise exposure to annoyance in  communities has become the generally accepted model for assessing the  effects of long-term noise exposure on communities.  According to this  study, when sound exposure levels are measured by a method that assigns  additional weight to sounds occurring between 10 p.m. and 7 a.m., and  those sound levels exceed 65 decibels, individuals report a noticeable  increase in annoyance.
section_title: Measures of Noise Identify Noise Levels of Single Aircraft Operations and Community Exposure
paragraphs: Methods for measuring airport-related noise provide different kinds of  information.  First, airport-related noise can be measured from single  events—such as an individual aircraft’s takeoff or landing—or as the  cumulative average level of noise that communities near airports are  exposed to over time.  Principal methods for measuring cumulative average  noise levels identify geographic areas exposed to the same noise levels but  apply different weights to flights occurring during different times of the  day.
subsections: section_title: Single Event Measures Provide Short-term Information
paragraphs: The noise from a single takeoff or landing usually starts when the sound  can be heard above the background noise; it reaches a maximum sound  level and then recedes until the sound is hidden below the background  noise level.  One of two measures of the noise from a single takeoff or  landing is commonly used:  (1) the Maximum Sound Level method, which  identifies the maximum sound level produced by the event, and (2) the  Sound Exposure Level method, which measures the total sound energy that  a listener is exposed to during a single event.
The Maximum Sound Level method is usually expressed in A-weighted  decibels when measuring aircraft events.  It does not provide any  information, however, about the duration of the event or the amount of  sound energy produced.
In contrast, the Sound Exposure Level method measures all of the sound  energy from the duration of a takeoff or landing to produce the sound level  that a person is exposed to from that event.  Thus, this method reflects both  the intensity and the duration of the sound that the takeoff or landing  produces.  For aircraft events, this method also usually uses A-weighted  decibels.  Because this method measures the cumulative sound energy  averaged over a single second of time, the sound exposure level for an  event that lasts longer than one second will be higher than the maximum  sound level for that same event.  Also, two events can have the same  maximum sound level but different sound exposure levels.  The event that  lasts the longest will have a higher decibel measure than the shorter event,  even though both may have the same maximum sound level.
To compare the different kinds of information these methods provide, FAA  calculated maximum sound levels and sound exposure levels for single  aircraft takeoffs and landings using an airport model that we designed.   The results illustrate the different concepts embodied in the two measures  of single events.  Figure 6 illustrates the measures produced by both  methods at one-half mile from the runway and at 1-mile intervals from the  runway, for both approach and takeoff operations, for the Boeing 747 and  C140 aircraft included in our model.  Similar figures for the four other  aircraft in our model appear in appendix VI.
Measuring the noise from a single takeoff or landing does not reflect or  measure the impact of the noise from several takeoffs or landings in  comparison with the impact of just one aircraft operation.  According to  FAA officials, although some research correlates the health and welfare  effects of noise generated by certain kinds of single events, the Federal  Interagency Committee on Noise pointed out in 1992 that there is no  accepted methodology for aggregating the information on the noise levels  of single events in a way that would explain the cumulative impact of those  events on people in the communities surrounding airports.  Thus, by  themselves, methods to measure the noise from single events are not  considered to describe the overall noise environment.
section_title: Noise in Communities Is Measured in Terms of Overall Exposure
paragraphs: The level of noise from airports that nearby communities are exposed to  depends on several factors, including the types of aircraft using the airport,  the overall number of takeoffs and landings, the time of day those aircraft  operations occur, the runways that are used, weather conditions, and  airport-specific flight procedures that affect the noise produced by a  takeoff or landing.  There are two approaches to measuring community  exposure to noise:  (1) identifying geographic areas on a map that are  exposed to the same noise levels or (2) determining the length of time that  a specific geographic area is exposed to particular noise levels.
subsections: section_title: Key Measurement Methods Use Contour Maps to Identify Geographic Areas Exposed to Noise Levels
paragraphs: The three main methods for measuring airport-related noise levels that  nearby communities are exposed to include (1) the Equivalent Sound Level  method; (2) the Day-Night Sound Level method; and (3) the Community  Noise Equivalent Level method.  These methods provide long-term, or  cumulative, measures of exposure to noise.  For each method, the key  factors that determine the noise exposure level affecting a community are  the types of aircraft using the airport, the number and type of engines on an  aircraft, the number of takeoffs and landings that occur during an average  day, and the time of day during which those aircraft operations occur.  The  measures are generally presented in the form of “noise contours” on  maps—lines around an airport that connect all the areas exposed to the  same average sound level.  A series of contours are drawn, usually at  5-decibel decrements from the airport, to produce a map that looks similar  to a land elevation map.  All three methods incorporate both the intensity  of sounds produced by single events and the average frequency of those  events.
The first method—the Equivalent Sound Level—measures the average  noise level over a specified time using A-weighted decibels.  Because the  method is based on a logarithmic average, it gives greater weight to higher  noise levels than to lower ones.  For example, if sound is measured at  50 decibels for a half hour and 100 decibels for a half hour, the Equivalent  Sound Level measure for the entire hour is 97 decibels, not the 75 that  would result from simple averaging.  Any time period can be used, with  typical time periods being 1 hour, or 1 day (24 hours).  Under this method,  all flights are weighted equally regardless of when they occur during the  day.
The second method—the Day-Night Sound Level—is the same as the  Equivalent Sound Level method for a 24-hour period, but it gives greater  weight to flights occurring during the nighttime—between 10 p.m. and 7 a.m. Additional weight is given to nighttime flights because they are more  likely to interrupt sleep, relaxation, or other activities and because the  background noise level during those hours is lower.  To reflect that greater  impact, the Day-Night Sound Level method equates 1 nighttime aircraft  operation to 10 equivalent daytime operations.  This effectively adds 10 decibels to the noise produced by each takeoff or landing that occurs  during those nighttime hours.  That is, the noise impact of each single  nighttime takeoff or landing is reflected in the noise exposure level as if it  were 10 daytime takeoffs or landings.  For example, if eight takeoffs and  eight landings occur between 7 a.m. and 10 p.m., they are reflected in the  noise exposure level as 16 aircraft operations.  If those same eight takeoffs  and eight landings all occur between 10 p.m. and 7 a.m., they are reflected  in the noise exposure levels as the equivalent of 160 aircraft operations.
Finally, the Community Noise Equivalent Level modifies the Day-Night  Sound Level method by adding additional weight to flights occurring  between the evening hours of 7 p.m. and 10 p.m. to account for an  assumption that greater interference with activities may be occurring  during the early evening than during the daytime.  The second and third  methods are considered to have only small differences.
Under each of the three methods, several different combinations of flights  can produce the same noise exposure level because factors such as the  total number of flights and the type of aircraft affect the noise exposure  levels.  For example, each of the following three scenarios will produce the  same 65 decibel noise exposure level under the Day-Night Sound Level  method:
500 aircraft operations with an average sound exposure level of
100 aircraft operations with an average sound exposure level of
50 aircraft operations with an average sound exposure level of  97.4 decibels.
Because different combinations of flights can produce the same noise  exposure level, and because these methods use additional weighting for  evening and/or nighttime flights, FAA does not consider these methods to  be good estimators of the noise level produced by a single event.
We compared the noise contours produced by these three methods at  various decibel levels using our airport model.  As figure 7 illustrates, the  Equivalent Sound Level method, which does not add weighting to evening  or nighttime flights, produced not only the smallest areas exposed to  various noise levels but also markedly smaller areas than the other two  methods, which include the effects of additional weighting.  The noise  contours produced by the Day-Night Sound Level method identified areas  that ranged from about 2-½ times as large to 3-½  times as large as the areas  exposed to the same noise levels under the Equivalent Sound Level  method.  On the other hand, the size of the areas exposed to the same noise  levels were almost identical under the Day-Night Sound Level method and  the Community Noise Equivalent Level method.  The latter produced a  5 percent or less increase in the size of those areas.
At our request, FAA also used our airport model to examine the results  from the different measurement methods when (1) flights were shifted by  time of day and (2) more aircraft operations were added.
In the first scenario, our model illustrated the effect of assigning additional  weight to flights occurring during different times of the day.  In this  scenario, FAA calculated the noise exposure levels for seven different flight  schedules.  All three methods produced the exact same contours when all  flights occurred during the day because no method applies additional  weighting to daytime flights.  However, when all flights occurred during the  nighttime, both the Day-Night Sound Level and the Community Noise  Equivalent Level produced contours that quadrupled the size of the areas  exposed to the different noise levels.  Table  3 illustrates the impact of  changing flight schedules.
In the second scenario, to understand how the number of aircraft  operations at an airport can affect the noise contours, we looked at the  results under each of the three methods, for seven cases in which the total  number of takeoffs and landings were increased at various increments.   The results showed that increasing the number of operations produced a  consistent increase in the size of the exposure area at each noise level  under each method.  That is, the greater the number of operations, the  further out each exposure level contour extended from the airport under  each method.  Consistent with the results illustrated in figure 7, the total  area affected by the Equivalent Sound Level method under each scenario  was noticeably smaller than that of the other two methods.  Also, the size of  the areas exposed to each noise level under the Community Noise  Equivalent Level method, for each level of operations tested, was less than  5 percent greater than the area affected by the Day-Night Sound Level  method.
section_title: Some Measurement Methods Provide Other Kinds of Noise Level Information
paragraphs: Two other measurement methods can provide additional kinds of  information about the noise exposure of a community.  The Time-Above  method can identify how much time during a designated time period—such  as a day—the noise exposure levels will exceed a specified decibel level.   The sound level must be specified—for example, 60 decibels.  This method  can then determine the length of time during a 24-hour period that noise  levels will exceed 60 decibels.
To illustrate the Time-Above method, our model produced data on how  many minutes in a 24-hour day the noise levels would be above 60 and  80 decibels at points one-half mile from each end of the runway and at  1-mile increments from the runway for both approach and takeoff  operations.  Table 4 illustrates the measures.
Another variation of this kind of information is the Lpercent method, which  identifies the noise level exceeded for a portion of a time period.  The  portion must be specified—for example, only 15 percent of a day.  This  approach might determine, then, that for 15 percent of the day, the noise  level exceeded 60 decibels—that is, for the rest of the day the noise level  was at or below 60 decibels.  FAA’s Integrated Noise Model does not  produce measures using this method.  Neither the Time-Above method nor  this method identifies the time of day the higher noise levels will occur.
section_title: FAA Selected the Day- Night Sound Level Method for Measuring Noise Exposure
paragraphs: The Aviation Safety and Noise Abatement Act of 1979 required the  Department of Transportation—after consultation with the Environmental  Protection Agency—to establish, by regulation, a single system for  measuring noise from airports and surrounding areas.  The act also  required the Secretary to establish a single method for measuring the  exposure of individuals to noise resulting from airport operations; that  method had to consider noise intensity, duration, frequency, and the time of  occurrence.  According to a Senate committee report, the act was intended  to establish a uniform approach for measuring airport-related noise in  order to facilitate the administration of a federal noise abatement program  that could, in turn, lead to a uniform approach for dealing with noise  problems in general.  Pursuant to that directive, in 1981, FAA selected the  A-weighted decibel and the Day-Night Sound Level method for measuring  airport-related noise.
In 1992, the Federal Interagency Committee on Noise noted that the Day- Night Sound Level method was practical and widely accepted.  After a  comprehensive review of measurement approaches, the interagency  committee determined that this method best met the statutory  requirements.  The committee concluded that there were no other  measurement methods of sufficient scientific standing to replace this  method as the primary cumulative noise exposure measurement method  and that the method correlates well with analyses of community annoyance  at various noise exposure levels.   The committee also noted that there  were no new data to justify a change in the use of extra weighting for  nighttime operations.  These conclusions are still valid, according to the  chairman of the Federal Interagency Committee on Aviation Noise (the  successor to the Federal Interagency Committee on Noise), which focuses  on aviation research related to noise.
A frequent criticism levied against the Day-Night Sound Level method is  that it does not effectively convey to people what they can actually expect  to hear in any given area, primarily because it does not identify the noise  levels generated by single aircraft takeoffs or landings.  The noise level  produced by the Day-Night Sound Level method is not the noise level that  people actually hear on an event by event basis—it is an average of the  cumulative sound levels over time.
To address this concern, the 1992 interagency committee report noted that  supplemental information—particularly information on noise generated by  individual takeoffs and landings—has been, and could continue to be,  useful, especially in characterizing specific events and in conveying a  clearer understanding of the potential effects of noise on people living and  working in the area.  The interagency committee recommended that federal  agencies continue to be allowed to use supplemental information at their  discretion when dealing with environmental impact analyses and  requirements.  An official of the interagency committee noted, however,  that while single event information is useful as a supplement, there is no  methodology for aggregating the effects of a single event into cumulative  impact analysis, as is the case with the Day-Night Sound Level method.
Because the interagency committee reiterated the usefulness of the Day- Night Sound Level method, all federal agencies have adopted it for  analyzing airport-related noise in their environmental assessments and  impact statements.  Some agencies, however, such as the Department of  Defense, use supplemental noise information, such as single event noise  measures, to provide a fuller picture of noise conditions and their potential  effects.  A proposed revision to FAA’s requirements for environmental  analyses states that FAA will also use supplemental information where  warranted.   The revision adds new guidance on the kinds of supplemental  information available and their use.
section_title: Aircraft Noise Standards Vary By Aircraft Design and Do Not Apply to Some Lighter Aircraft
paragraphs: FAA establishes the standards limiting the noise that civil subsonic turbojet  aircraft are permitted to generate.   Those standards are generally based  on an aircraft’s weight and the number of engines and generally allow  heavier aircraft to generate more noise than lighter aircraft.  The statutory  deadline of December 31,1999, for compliance with “stage 3” standards did  not apply to aircraft weighing 75,000 pounds or less that were already in  operation.  As of October 1, 1999, more than 2,750 aircraft were not subject  to the stage 3 compliance deadline.
subsections: section_title: Noise Standards Generally Permit Heavier Aircraft to Generate More Noise Than Lighter Aircraft
paragraphs: FAA regulations establish the maximum noise levels that civil subsonic  turbojet aircraft are allowed to generate for takeoff, landing, and “sideline”  measurements.  The standards for each of these kinds of measurements are  different, but, in general, these standards vary with the weight of the  aircraft.  The standards allow heavier aircraft to be noisier than lighter  aircraft because, according to FAA, the noise generated by an aircraft is  generally determined by the thrust powering the aircraft; the amount of  thrust an aircraft needs is proportional to the weight of the plane—that is,  the heavier the aircraft, the more thrust it needs.  According to an aircraft  noise expert, lower noise standards for lighter aircraft is one of the reasons  that a stage 2 aircraft weighing 75,000 pounds or less may make less noise  than a heavier aircraft that meets the more stringent stage 3 standards.  For  takeoff, stage 3 noise standards also vary on the basis of the number of  engines; generally, the more engines an aircraft design has, the higher the  permitted takeoff noise levels.  Stage 3 standards for takeoff, sideline, and  approach are shown in appendix VII.
The United States is a member of the International Civil Aviation  Organization—the international authority on civil aviation standards—and  as such participates in that organization’s activities regarding aircraft noise  standards.  Members of the organization—are considering more stringent  noise standards.  The organization’s Committee on Aviation Environmental  Protection is reviewing several options, identified by its Noise Scenarios  Group in a November 1999 report, including: (1) taking no action on more  stringent standards, (2) adopting a standard only for new aircraft designs,  or (3) adopting more stringent standards with various schedules for the  phaseout of noisier aircraft. Guidance governing the Committee’s work  directs it to consider such factors as technical feasibility, economic  reasonableness, and the environmental benefit to be achieved.  The  organization is expected to adopt a resolution when it meets in September  2001 on a more stringent standard and the phaseout of stage 3 aircraft.   Implementation of the new standard, and phaseout of the noisier aircraft,  would be up to the member nations.
The European Union has banned, after May 1, 2000, stage 2 aircraft that  were modified to meet stage 3 noise standards, unless the aircraft were  already operating or registered in a member country before that date.  The  European Union also adopted restrictions on operating modified aircraft  after April 1, 2002.  The United States filed a formal complaint with the  International Civil Aviation Organization on March 14, 2000, alleging that  the European Union’s ban discriminates against U.S. aircraft in violation of  the agreement establishing the organization.
section_title: Existing Aircraft Weighing 75,000 Pounds or Less Have Been Exempt From Operating Restrictions
paragraphs: Both stage 1 and stage 2 aircraft that did not meet more stringent noise  standards by specified dates have been prohibited from operating after  those deadlines, but that prohibition does not apply to aircraft in service  that weigh 75,000 pounds or less.  FAA did not require the retirement of the  lighter stage 1 aircraft that did not meet stage 2 standards because FAA  concluded it was not technologically practicable or economically  reasonable to modify these aircraft.  The statute prohibiting the operation  of stage 2 aircraft that did not meet stage 3 standards by a certain date does  not apply to aircraft weighing 75,000 pounds or less.
subsections: section_title: Exemption From the Stage 1 Operating Deadline Was for Technological and Economic Reasons
paragraphs: When FAA amends regulations controlling aircraft noise, it must consider  several factors, including whether the proposed regulations are  technologically practicable, economically reasonable, and appropriate for  the types of aircraft, aircraft engines, or aircraft certifications that the  regulations apply to.  FAA must also consider the extent to which any  proposed amendments protect the public health and welfare.
In 1976, FAA considered amending its regulations to require stage 1 aircraft  already in service to meet stage 2 noise standards or be prohibited from  operating at U.S. airports.  At that time, the Environmental Protection  Agency recommended that the deadline for compliance be applied to all  civil subsonic turbojet aircraft regardless of weight.  That agency  contended that all of those aircraft were capable of meeting stage 2  standards by using various engine modifications or replacement options.  It  determined that because all newly produced aircraft weighing  75,000 pounds or less had to comply with stage 2 noise standards after  January 1, 1975, there seemed to be no valid justification for permitting  stage 1 aircraft to operate indefinitely.  While some who commented on  FAA’s proposed amendment supported the Environmental Protection  Agency’s conclusion, others challenged it, contending, for example, that  (1) the technology was not available to enable lighter aircraft to meet the  stage 2 noise standards or (2) other sources, such as heavier aircraft or  traffic from regularly scheduled passenger service flights, were the primary  causes of the noise problems.
FAA chose not to apply the operating deadline for stage 1 aircraft to aircraft  weighing 75,000 pounds or less.  FAA concluded that it could not impose  operating noise limits on the lighter aircraft at that time in a manner that  was fully consistent with its obligations under the law for two reasons.   First, FAA determined that the cost-effectiveness of implementing the  kinds of modifications needed to retrofit an existing aircraft was  questionable and, therefore, not technologically practicable.   It concluded  that noise reduction modifications to the lighter aircraft could be applied  during the original design and manufacture of an aircraft, but such  modifications involved substantial redesign efforts that, while reasonable  when spread over the production process, were of doubtful cost- effectiveness if accomplished by retrofitting.  FAA considered only  retrofitting options—engine modification or replacement—as acceptable  for meeting noise standards; flight operation noise abatement procedures  were not an acceptable means for complying with the noise standards.
Second, FAA determined that available information was not sufficient to  assess the economic impact on owners of an across-the-board requirement  to retrofit the lighter aircraft.  Available information was limited because  the aircraft were so varied in their use and mission and were frequently the  only—or one of a few—aircraft owned by the owner.  In addition, FAA  determined that the availability of supplies for small engine manufacturers  needed further study before FAA could assess the overall economic impact  of specific compliance dates on aircraft owners.
In December 1997, however, the National Business Aviation Association, a  membership organization of companies that operate aircraft, passed a  resolution calling for the group’s 5,200 members to refrain from adding new  stage 1 aircraft to their fleets beginning in January 2000 and to end the  operation of stage 1 aircraft by 2005.
section_title: Statutory Deadline for Stage 2 Retirement Did Not Apply to the Lighter Aircraft
paragraphs: The Airport Noise and Capacity Act of 1990 established December 31, 1999,  as the deadline for phasing out stage 2 aircraft that were not modified to  meet stage 3 noise standards.  The statute, however, specifically applied the  phaseout only to aircraft weighing more than 75,000 pounds.  The  legislative history of the act provides no discussion on why the statutory  phaseout was not applied to the lighter aircraft. As of October 1, 1999, just  over 9,000 civil subsonic turbojet aircraft that weighed 75,000 pounds or  less were certified by FAA as airworthy.  About 31 percent of those, or just  over 2,770, are stage 1 or stage 2 aircraft that may still operate at U.S.  airports after December 31, 1999.
The 1990 act, however, also established federal review requirements when  an airport wants to control noise by imposing more stringent limitations on  aircrafts’ use of the airport than federal regulations provide.  The act  directed the Secretary of Transportation to establish a national program for  reviewing airport restrictions on the operation of stage 2 and stage 3  aircraft.  It also required the Secretary to study whether federal review  should be applied to restrictions on stage 2 aircraft weighing less than  75,000 pounds.  The study recommended that the same procedures should  apply to all stage 2 aircraft, regardless of weight.  FAA adopted that  recommendation.  Thus, an airport may impose a noise or access  restriction on stage 2 aircraft, whatever its weight, if the airport operator  publishes the proposed restriction and prepares and makes certain  analyses available for public comment at least 180 days before the effective  date of the restriction.  Unlike noise or access restrictions proposed for  stage 3 aircraft, FAA approval is not required.
section_title: FAA’s Land Use Planning Initiative Focuses First on Improving Access to Information
paragraphs: Land use planning is one way that communities can alleviate the impact of  airport-related noise in areas near airports.  While the federal government  has no decision-making authority in land use planning, FAA does have  some responsibility to address land use issues in connection with its  administration of airport-related noise programs.  For example, as required  by law, FAA has identified the kinds of land uses that are compatible with  various noise levels communities may be exposed to because of a nearby  airport.  Looking to the future, FAA has announced five short-term actions  under its Land Use Planning Initiative, which it launched to help prevent  incompatible land uses.  Reviewing the comments provided by the aviation  sector and the general public, we identified four principal areas of concern  associated with the initiative.
subsections: section_title: FAA Facilitates State and Local Land Use Planning Efforts
paragraphs: Through land use planning, communities determine what kinds of  development—for example, residential or industrial—will occur within  their jurisdictions.   Communities can use such land use planning to reduce  or alleviate the impact of airport-related noise.  For example, communities  may prohibit the construction of schools within a certain distance from an  airport so that airport-related noise will not interrupt classes.  While the  federal government has no direct decision-making authority over land use  planning, FAA can nevertheless help communities consider the impact of  nearby airports as they develop their plans.  For example, the Aviation  Safety and Noise Abatement Act of 1979 requires FAA to identify land uses  that would not be compatible with noise generated by the operation of a  nearby airport.  As a result, FAA identified some land uses, such as homes  and schools, as being incompatible with noise exposure levels of  65 decibels or higher (using the Day-Night Sound Level method) that occur  very close to an airport, while other land uses, such as industrial and  commercial uses, could successfully be located close to an airport without  interfering with activity.  Although FAA can provide land use planning  guidance, it is up to the state and to local communities to apply this  guidance.
The recent transition to quieter aircraft can lower noise exposure levels in  some communities, but FAA has been concerned that noise levels may rise  again around some airports if the number of flights increase to meet the  expected growth in passenger levels.  According to an FAA official, even  where noise levels do not rise, maintaining a buffer zone between the  airport and certain land uses, such as homes and schools, serves a general  interest in maintaining a quieter environment.  Because of its concerns,  FAA embarked on a Land Use Planning Initiative to help state and local  governments achieve and maintain compatible land uses around airports.   Under this Initiative, in January 1995, FAA sponsored a Study Group on  Compatible Land Use, which was composed of community, airport, and  aviation representatives.  This group recommended federal actions that  could promote compatible land use planning around airports.  In May 1998,  FAA issued a request in the Federal Register for additional suggestions to  help state and local governments’ planning efforts.  After reviewing the  submissions, FAA announced in May 1999 that it would implement five  short-term actions while it continued its review of other suggestions.  FAA  expects to announce additional actions in the future on training, education,  satellite navigation, research and development, and proposed legislation.
section_title: Short-Term Actions Aim at Improving the Communication of Information
paragraphs: The five short-term actions that FAA announced in May 1999 focus  primarily on improving the communication of its noise policies and noise  compatibility information in order to help communities and airports work  together to minimize the noise impacts of airports.  Table 5 provides an  overview of each action, the FAA office responsible for implementation,  and the implementation status of each action.
The implementation goal for these short-term actions was originally  September 30, 1999.  FAA has completed implementation of two of these  actions.  To establish the information clearinghouse, FAA created an  Internet website.  To provide a clearer understanding of its actions  addressing certain noise exposure situations, FAA issued revisions in June  1999 to its order that provides guidance on conducting environmental  impact analyses for airports.  The November implementation goal for the  remaining three actions was delayed until March 31, 2000, primarily  because FAA was reorganizing its Office of Environment and Energy, which  is responsible for the Land Use Planning Initiative.  As of April 26, 2000, an  FAA official expected the remaining actions to be implemented by  May 2000.
The clearinghouse that FAA established on land use information can be  accessed at www.faa.gov/arp/app600/5054a/landuse.htm.  According to  FAA officials, this website will become the primary means for distributing  information made available by some of these short-term actions—including  the information packages—and any additional actions approved in the  future.  The website has links to information on Washington State’s website  for its land use planning program and will eventually link to other states  that have similar websites.  It also incorporates links to websites for land  use planning associations, periodicals, and legal planning specialists.  FAA  plans to add information and/or links as warranted.
FAA stated that the objectives of its fifth action include (1) providing  greater focus on the use of flight procedures to mitigate the effects of noise  over certain areas and (2) emphasizing consultations with airports and  communities.  FAA’s overall goal is to clarify the actions it might take to  address rising noise exposure levels.  FAA’s revised guidance, however,  does not appear to achieve its objective of providing greater focus on the  use of flight procedures because the revisions contain no explicit  discussion of the use of flight procedures to mitigate the effects of noise  over certain areas.  Furthermore, this lack of discussion contrasts with the  detailed description FAA provides to incorporate other changes to that  same order, including changes pending that pertain to the use of  supplemental information in environmental impact analyses.
subsections: section_title: Initiative Raises Key Issues in Noise Mitigation Efforts
paragraphs: In reviewing the public comments on the Initiative and from our  discussions with aviation officials and other experts, we identified four  principal areas of concern associated with the Initiative.  These areas  involve determining (1) what is the most effective use of the agency’s  limited resources when addressing airport-related noise, (2) whether the  65 decibel level defining incompatible land uses should be lowered,  (3) whether additional information, such as single event noise levels,  should be required when analyzing noise impacts, and (4) what is the best  use of federally authorized investment in the growth of airport capacity in  view of the noise and physical expansion constraints affecting many  airports.   Table 6 summarizes the context and scope of these issues.
section_title: Observations
paragraphs: Through its responsibilities for aviation noise, FAA plays a critical role in  helping to reduce the noise that airports generate and to mitigate the  effects of that noise on surrounding communities.  While FAA has  accomplished much in fulfilling its statutory responsibilities, the issues  raised in connection with FAA’s Land Use Planning Initiative are not  necessarily new and show that more work remains to be done on resolving  controversies regarding airport-related noise.  Addressing these issues will  require balancing the needs of the different—and often conflicting— interests of airports, airlines, manufacturers, passengers, general aviation,  and the communities near the airports.  Resolution of these issues will also  need to take into account concerns about the environment, as well as  advances in technology.
section_title: Agency Comments
paragraphs: We provided the Department of Transportation, the National Association of  State Aviation Officials, an advisory panel of five experts, the Airports  Council International-North America, the General Aviation Manufacturers  Association, and the Air Transport Association of America, Inc. with copies  of the draft report for their  review and comment.
We met with officials from the Department of Transportation, including  FAA’s Manager, Community and Environmental Needs Division, and spoke  with FAA’s Manager, Noise Division.  These officials generally agreed with  the facts in the report and provided clarifying comments, which we  incorporated as appropriate.  The National Association of State Aviation  Officials and the advisory panel of experts generally agreed with the facts  in the report and provided us with technical and clarifying comments,  which we incorporated as appropriate.  The Airports Council International- North America provided no comments.
We spoke with the President of the General Aviation Manufacturers  Association, who stated that the report reflects a good effort to make a  difficult topic understandable.  However, he said the Association had three  concerns about the accuracy of the presentation.  The Association believes  the draft report (1) implied that aircraft not subject to phased compliance  with operating noise limits were not subject to any noise standards, when  in fact, all aircraft manufactured after December 31, 1974, must meet  stage 3 noise standards; (2) did not explain that the exception of lighter  aircraft from compliance with stage 3 operating noise limits was consistent  with international operating rules developed by the International Civil  Aviation Organization; and (3) overestimated how many aircraft weighing  75,000 pounds or less still operate in the United States.  The Association  further believed the general aviation aircraft selected for our airport model  were not representative of the operating fleet.
With regard to the Association’s first concern, we believe the draft report  accurately explained the progressive application of noise standards to  aircraft.  However, we revised it to clarify the distinction between noise  standards for the certification of aircraft as airworthy and the application  of those standards to operating aircraft.  Regarding the second concern,  this report focuses on FAA’s roles and responsibilities rather than on  international activities.  Nevertheless, we revised the draft report to clarify  that the United States is a member of the International Civil Aviation  Organization and as such participates in that organization’s activities  regarding aircraft noise standards.  Concerning the final issue, data in our  draft report on the number of aircraft weighing 75,000 pounds or less  include all such aircraft certificated by FAA as airworthy as of October 1,  1999.  In contrast, data provided by the Association include only the  operating business fleet, which is a subset of FAA’s list of certificated  aircraft.  With regard to our selection of aircraft for the model, we began  with the universe of certificated aircraft and selected two general aviation  aircraft from this list, as well as four others, to reflect both stage 2 and  stage 3 aircraft, and lighter and heavier aircraft.  We revised the draft report  to clarify that we selected aircraft from the list of certificated aircraft.
We met with officials from the Air Transport Association of America, Inc.,  who stated that the draft report was generally very good, but who  expressed five concerns.  They believe the draft report (1) did not fully  recognize, in its discussion of the potential impact of growth in air traffic,  the significant progress that the Congress, FAA, airports, and the airlines  have made in reducing the number of people exposed to noise from  aircraft, nor did it recognize that aircraft used to achieve additional growth  may be quieter; (2) did not fully reflect the role of international agreements  and obligations related to noise control; (3) was overly broad in its  discussion of  flight procedures for abating noise when explaining why FAA  did not require aircraft weighing 75,000 pounds or less to be retired if they  did not meet stage 2 standards; (4) included only two aircraft in the airport  model, one of which is no longer being produced, and did not address  current production aircraft; and (5) did not fully reflect the relationship and  potential trade-offs between noise stringency standards and aircraft  emissions.  The Association also provided technical and clarifying  comments, which we incorporated as appropriate.
With regard to the first concern, we agree that the aviation industry and the  federal government have made substantial progress in reducing noise  generated by airports.  However, forecast growth in aviation activity could  reduce or eliminate the benefits at individual airports.  If current aircraft  are replaced with quieter aircraft, the impact of the quieter aircraft on  airport-related noise will depend on several factors including the extent to  which aircraft operations increase and when operations occur.  We revised  the draft report to clarify these points.
With regard to the second issue, we agree that the international  administrative and regulatory framework for developing and implementing  aircraft noise standards is important for the aviation industry.  However,  this report focuses on FAA’s role in major noise-related programs rather  than on international activities.  Nevertheless, we revised the draft report  to clarify that the United States is a member of the International Civil  Aviation Organization and as such participates in that organization’s  activities regarding aircraft noise standards.
Regarding the third concern, our draft report provided FAA’s rationale for  not applying a retirement deadline to stage 1 aircraft weighing  75,000 pounds or less.  As noted in the report, FAA did not consider flight  operations to be an appropriate operational noise abatement procedure for  the purpose of meeting aircraft noise standards.  As also noted, however,  FAA did consider flight operations to be appropriate for further reducing  noise where circumstances warrant.  Accordingly, we did not revise this  discussion in our draft report.
With regard to the fourth concern, the Association incorrectly concluded  that the airport model included only two aircraft.  As appendix V of the  report explains, the model was designed to provide a reasonable facsimile  of an airport for use in comparing and illustrating the various noise  measurement methods.  Six aircraft were selected from FAA’s list of  certificated aircraft to represent categories of aircraft operations.  Aircraft  selection was not intended to include only those aircraft currently in  production because that would have eliminated stage 2 aircraft from the  model.
With regard to the final concern, we revised the draft report to  acknowledge that reducing aircraft noise may result in higher aircraft  emissions.