Aviation and the Environment

Since the introduction of turbojet aircraft in the late 1950s for commercial passenger service, airport noise has affected many surrounding communities and has become a constraint to airport development. Airport noise is produced primarily when planes take off and land, but engine maintenance and the taxiing of aircraft on runways also contribute to the problem. New technology has been making aircraft quieter, and since 1969 the Federal Aviation Administration (FAA) has been limiting the noise that 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, the expected growth in air traffic may yield 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. This report determines (1) the type of projects that are eligible for federally authorized funding to reduce airport noise, (2) the differences in the current methods for measuring the impact of airport noise, (3) FAA's current noise standards for civil subsonic turbojets and the reasons some of those aircraft are not required to comply with these or earlier standards, and (4) the status of FAA's land use planning initiative and the major issues that the initiative has raised about how best to address airport noise.

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