Fuel is the airline industry's second largest expense, exceeded only by labor. The major U.S. airlines spend more than $10 billion a year on fuel, which is approximately 10 percent of total operating expenses. As a result, increased fuel efficiency has been a top industry priority for many years, and the industry has made giant strides in that regard. Since deregulation, U.S. airlines have increased fuel efficiency nearly 65 percent by:
- investing in new, environmentally efficient aircraft and engines;
- lowering cruising speeds;
- using computers to determine optimum fuel loads and to select altitudes and routes that minimize fuel burn;
using flight simulators rather than real aircraft for pilot training;
- holding aircraft at gates, with engines shut down, when weather or other problems delay takeoff, when appropriate;
- using only one engine to taxi;
- keeping aircraft exteriors clean to minimize aerodynamic drag.
Most important, the airlines have invested, and continue to invest, billions of dollars in new aircraft and engines that are far more efficient than the models they replace. The Airbus A320 and Boeing 737-300, for example, transport twice as many revenue passenger miles per gallon of fuel than the DC-9 and earlier versions of the 737. In addition, they emit smaller amounts of the gases of concern to scientists studying global warming and other environmental issues.