National Airspace System

Pursuant to a congressional request, GAO reviewed the American Airlines' study on air traffic congestion focusing on: (1) providing observations on its findings; and (2) reviewing other studies of air traffic congestion, assessing the limitations of these types of studies, and identifying the next steps in addressing the problem of air traffic congestion.

GAO noted that: (1) American Airlines' study focused on two scenarios of future air traffic congestion; (2) under the first scenario--most frequently cited by others--the study found that by 2005 airline flight delays would interfere with airline flight schedules and by 2014 these delays would have a crippling effect on scheduled flight operations; (3) this scenario assumed that air traffic would grow at a rate of 2.3 percent annually and that the current National Airspace System would not be modernized; (4) GAO found, as did American Airlines, that the do nothing scenario is unrealistic because it ignores various actions under way or planned by the Federal Aviation Administration and others to alleviate future air traffic congestion; (5) the second scenario also assumed that air traffic would grow by 2.3 percent annually, but in contrast to the first scenario, it factored in plans to modernize the National Airspace System; (6) under this scenario, American Airlines concluded that with the implementation of a new system of air traffic management known as free flight, delays through 2025 would be substantially shorter than the average delay of 1.5 minutes experienced in 1996; (7) officials from two consulting firms that also studied air traffic congestion--MITRE Corporation and the Logistics Management Institute (LMI)--told GAO the American Airlines study was important because it elevated a problem that had not received sufficient attention; (8) however, these officials also stated that the value of the study was limited because it did not discuss in detail: (a) air traffic congestion at lower altitudes, where MITRE and LMI consider the problem to be most severe; and (b) the methodologies and sources of data that were used to develop the study's results; and (9) in addition, GAO found that studies of future air traffic congestion are inherently limited by the difficulty of predicting factors such as air traffic growth and the impact of new technologies and procedures.