TABLE 5-7 Flight Delays by Cause by Month: January-December 2004

Number, except as noted

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KEY: NA = not applicable.

NOTES: Air carrier delay is due to circumstances within the airline's control (e.g., maintenance or crew problems, aircraft cleaning, baggage loading, and fueling). Aircraft arriving late refers to the late arrival of the previous flight where the same aircraft is used for the present flight, causing the present flight to depart late. National Airspace System are delays and cancellations attributable to the national aviation system that refer to a broad set of conditions (e.g., nonextreme weather conditions, airport operations, heavy traffic volume, and air traffic control). A security delay is a delay or cancellation caused by evacuation of a terminal or concourse, reboarding of the aircraft because of a security breach, inoperative screening equipment, and/or long lines in excess of 29 minutes at screening areas. Extreme weather is significant meteorological conditions (actual or forecast) that, in the judgment of the carrier, delays or prevents the operation of a flight (e.g., tornado, blizzard, or hurricane).

The airlines required to report in 2004 were: Alaska Airlines, America West Airlines, American Airlines, American Eagle Airlines, ATA Airline (formerly doing business as American Trans Air), Atlantic Coast Airlines (became Independence Air in late 2004), Atlantic Southeast Airlines, Comair, Continental Airlines, Continental Express, Delta Airlines, ExpressJet Airlines, Northwest Airlines, Southwest Airlines, SkyWest Airlines, United Airlines, and US Airways. JetBlue Airways and Hawaiian Airlines reported voluntarily.

SOURCE: U.S. Department of Transportation, Research and Innovative Technology Administration, Bureau of Transportation Statistics, Airline Service Quality Performance data, March 2005.