effects of emissions. Studies provide a wealth of information on the impact of emissions, although not on the specific consequences of aviation emissions.

One approach for dealing with the impact of aviation on local air quality would be to include aviation in economywide pollution trading programs. Allowing aviation operators and entities from other industries to trade pollution permits could significantly reduce the total cost of meeting local emissions goals (FESG, 2001). Costs would be reduced because not all polluters or industries have the same technological and economic opportunities to reduce emissions; where substantial differences in cost exist, the lower-cost alternatives should be selected. Pollution trading programs would allow operators and, ultimately, consumers to face the full cost of compliance. It would also provide a framework for operators to benefit from using equipment with lower-than-required levels of emissions, by allowing them to sell their permits to entities with higher levels of emissions.

The shortfall in capacity at many airports also directly affects the amount of emissions produced. While FAA flow control programs do a good job of holding aircraft at gates when air traffic delays are building up, in many cases aircraft auxiliary power units continue to operate.2 Also, when aircraft are released from a gate, they are often put into a long line for takeoff. Likewise, arriving aircraft can be sent to holding pens for long periods (with engines running) until gates are released. Automobile traffic can also build up during peak periods. Better matching of demand and capacity at airports would improve the local emissions picture.

Economic Costs of Emissions at Altitude

The economic consequences of climate change are potentially catastrophic in the long term. However, the contribution that aviation may be making to global warming and climate change is still uncertain. Because these are essentially global issues, they are best addressed through global institutions (i.e., ICAO), as discussed in Chapter 3.


Currently, there are essentially no financial incentives for industry to develop and deploy environmental technologies that go beyond regulatory requirements. In fact, spending resources to go beyond regulatory requirements can put airlines at a competitive disadvantage. As a result, NASA research may generate new technology that the private sector has little or no incentive to adopt. Even so, mitigating the environmental impact of a growing air transportation system will require enlightened application of technology—and environmental policies should be framed to encourage industry to develop advanced environmental technologies and use them in operational products as they become available.

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.


FESG (Forecasting and Economic Support Group). 2001. Report on Economic Analysis of Potential Market-Based Options for Reduction of CO2 Emissions from Aviation. 5th meeting of ICAO’s Committee on Aviation Environmental Protection (CAEP/5). January 2001. Montreal, Canada: ICAO.

Schipper, Y., P. Nijkamp, and P. Rietveld. 1998. Why do aircraft noise value estimates differ? A meta-analysis. Journal of Air Transport Management 4:117–124.


Auxiliary power units are small jet turbines that provide aircraft with electrical power when the main engines are shut down and ground power is not connected.

The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement