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

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

Number, except as noted

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  Air carrier delay Aircraft arriving late National Airspace System delay Security delay Extreme weather Total number of flights delayed Delays as a percentage of scheduled flights
January 32,476 33,466 53,963 424 7,907 128,236 29.3
February 26,755 31,689 49,883 342 5,848 114,517 26.7
March 25,760 30,557 43,941 280 3,494 104,031 21.3
April 23,687 26,704 39,974 260 3,129 93,754 19.4
May 27,719 34,400 52,073 237 6,591 121,019 26.2
June 35,700 45,783 57,483 422 9,339 148,726 34.6
July 36,633 42,829 49,519 407 6,610 135,999 29.2
August 32,262 39,299 45,378 371 6,574 123,884 25.4
September 21,722 20,462 29,337 384 3,242 75,147 15.3
October 27,532 32,084 43,257 321 5,146 108,341 21.9
November 29,385 33,891 44,134 391 5,895 113,696 24.6
December 43,945 49,258 52,199 809 7,831 154,041 35.5
12-month average number 30,298 35,035 46,762 387 5,967 118,449 NA
12-month average percent 25.6 29.6 39.5 0.3 5.0 NA NA

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.