AIRCRAFT NOISE

Aviation noise reduces property values, contributes to delays in expanding airport facilities, and prompts operational restrictions on existing runways that increase congestion, leading to travel delays, high ticket prices, and high airline capital and operating costs. The situation would be much worse, however, if not for past investments in advanced technology. Over the past 30 years, the number of people in the United States affected by noise (i.e., the number of people who experience a day-night average sound level of 55 dB) has been reduced by a factor of 15, and the number of people affected by noise has been reduced by a factor of 100, as measured per unit of service provided (revenue-passenger-kilometer).

The most significant limitations to further reductions in the effect of aviation noise (or emissions) include growth in demand, long lead times for technology development and adoption, long lifetimes of aircraft in the fleet, high development and capital costs in aerospace, high residual value of the existing fleet, and low levels of research and development funding. While spending huge sums on local palliatives such as soundproofing buildings, the federal government reduced funding for the research that would quiet the entire fleet in the decades ahead. For example, the noise reduction element of NASA’s Advanced Subsonic Technology Program was an excellent model for government-industry collaborations involved in commercialization of advanced technology. This program has been terminated, however, and replaced with a new program with fewer resources and less industry involvement.

In 2001, the FAA expended about $500 million on noise abatement, while the FAA and NASA together expended less than $60 million on noise and emissions research. The need to place more emphasis on research was noted in the fiscal year 2002 appropriations for the Department of Transportation, which directed that $20 million from the Airport and Airway Trust Fund be used to accelerate the introduction of quieter aircraft technologies. These funds were provided to the FAA, with the expectation that it would “work directly with” NASA “to advance aircraft engine noise research,” and about $14 million is being used to augment NASA research funding in this area. Congress took this action because community opposition to aircraft noise is preventing the necessary expansion of some airports and because “aircraft noise results in millions of federal dollars being spent each year on mitigation measures, diverting funds which could be applied to capacity enhancement or safety projects” (Congress, 2001). The committee endorses this action as a first step in reducing the imbalance in the allocation of aircraft noise funding. Much more needs to be done.

Most federal research on noise reduction is performed or managed by NASA. NASA’s goals for noise reduction are to cut the perceived noise of future subsonic aircraft in half (i.e., by 10 dB) between 1997 and 2007 and to cut the noise in half again by 2022 (NASA, 2002). Achieving these goals will be very difficult—and will require a rate of technological advance that is greater than the historical record would predict (see Figure ES-1). Furthermore, even in the unlikely event that these aggressive goals are achieved, noise may continue to constrain the U.S. air transportation system, in large part because communities near airports are placing greater emphasis on a low-noise environment as part of their quality of life.

The Federal Interagency Committee for Aircraft Noise facilitates information sharing among federal agencies interested in aircraft noise. This committee could be strengthened and made more effective if agencies appointed personnel who have budgetary authority within their home organizations as members of the committee.

Recommendation—Balanced Allocation of Funds. Federal expenditures to reduce noise should be reallocated to shift some funds from local abatement, which provides near-term relief for affected communities, to research and technology that will ultimately reduce the total noise produced by aviation. Currently, much more funding is devoted to local abatement than to research and technology. Also, to avoid raising unrealistic expectations, the federal government should realign research goals with funding allocations either by relaxing the goals or, preferably, by reallocating some noise abatement funds to research and technology.

Recommendation—Technology Maturity and Scope. NASA and other agencies should sustain the most attractive noise reduction research to a technology readiness level high enough (i.e., technology readiness level 6, as defined by NASA) to reduce the technical risk and make it worthwhile for industry to complete development and deploy new technologies in commercial products, even if this occurs at the expense of stopping other research at lower technology readiness levels. NASA and the FAA, in collaboration with other stakeholders (e.g., manufacturers, airlines, airport authorities, local governments, and nongovernmental organizations), should also support research to accomplish the following:

  • Establish more clearly the connection between noise and capacity constraints.

  • Develop clear metrics for assessing the effectiveness of NASA and FAA noise-modeling efforts.

  • Implement a strategic plan for improving noise models based upon the metrics.

  • Harmonize U.S. noise reduction research with similar European research.

Recommendation—Interagency Coordination. Interagency coordination on aircraft noise research should be enhanced by ensuring that the members of the Federal Interagency Committee for Aircraft Noise have budget authority



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