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 2-3. 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 within their own organizations to implement a coordinated strategy for reducing aviation noise.

Finding 3-1. Gap Between Technology and Demand. Continuation of ongoing technology research will reduce fuel consumption per revenue-passenger-kilometer by about 1 percent per year over the next 15 to 20 years. During the same time, the demand for air transportation services is expected to increase by 3 to 5 percent per year. An aggressive, broad-based technology program that encompasses propulsion systems, the airframe, and operational systems and procedures could significantly close this gap. Existing allocations of research funding and funding trends within NASA and the FAA do not support such a program.

Finding 3-2. Gap Between NASA Goals and Programs. NASA funding to achieve its goals for reducing CO2 and NOx emissions is insufficient to reach the specified milestones on time. Little or no funding is available for research related to other emissions, such as hydrocarbons, particulates, and aerosols, which may also have significant effects on the atmosphere locally, regionally, or globally.

Recommendation 3-1. Research on Global, Regional, and Local Emissions. NASA should continue to take the lead in supporting federal research to investigate the relationships among aircraft emissions (CO2, water vapor, NOx, SOx, aerosols, particulates, unburned hydrocarbons, and other hazardous air pollutants) in the stratosphere, troposphere, and near the ground, and the resulting changes in cirrus clouds, ozone, climate, and air quality (globally, regionally, and locally, as appropriate). Other agencies interested in aircraft or the environment should also support basic research related to these programmatic goals.

Recommendation 3-2. Eliminating Uncertainties. NASA should support additional research on the environmental effects of aviation to ensure that technology goals are appropriate and to validate that regulatory standards will effectively limit potential environmental and public health effects of aircraft emissions, while eliminating uncertainties that could lead to unnecessarily strict regulations.

Finding 4-1. Environmental Impact. The environmental impact of any industry, including aviation, would be reduced if equipment manufacturers, service providers, and consumers directly faced the full costs of their activities, including environmental costs. For air transportation, this would require industry, consumers, and others who benefit from a robust air transportation system to face the full costs of operations.

Recommendation 4-1. Considering All Costs and Benefits. To support the formulation of environmental goals and air transportation policies, government and industry should invest in comprehensive interdisciplinary studies that quantify the marginal costs of environmental protection policies, the full economic benefits of providing transportation services while reducing the costs (in terms of noise, emissions, and congestion), and the potential of financial incentives to encourage the development and use of equipment that goes beyond regulatory standards.

Finding 5-1. Status of Environmental Research. Research seeking to mitigate the environmental impacts of aviation is important to national and global well-being, but present efforts are operating with ambitious goals, unrealistic time-tables for meeting them, and few and diminishing resources.

Recommendation 5-1. Taking Advantage of Experience. The following lessons, learned since the advent of jet-powered aircraft, should be used to formulate and evaluate strategies for reducing the environmental effects of aviation:

  • Success is not easy—it requires government support and federal leadership in research and development of new technology. Establishing a strong partnership involving federal, state, industry, and university programs is essential to progress.

  • Changes in the impact of aviation on the environment occur on the scale of decades as fleets evolve; technological success in reducing adverse impacts occurs on the same or longer scales.

  • The formulation of technological strategies to reduce the environmental impacts of aviation is hampered by significant uncertainties about (1) the long-term effects of aviation on the atmosphere, (2) economic factors associated with aircraft noise and emissions, and (3)

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