TABLE 3-4 Average Monthly Number of Delays by Cause: July 2003-January 2004

TABLE 3-4 Average Monthly Number of Delays by Cause: July 2003-January 2004

Number, except as noted

Excel | CSV | Graphic Version

  July August September October November December January 7-month average
Air carrier delay 28,040 27,897 17,194 19,293 21,240 30,155 32,476 25,185
Aircraft arriving late 30,588 29,814 16,764 18,177 24,978 35,104 33,466 26,984
Security delay 324 376 109 259 185 467 424 306
National Airspace System delay 10,114 10,588 7,757 7,499 11,598 12,685 13,491 10,533
Extreme weather 5,170 5,887 2,292 1,667 3,381 4,201 7,907 4,358
Total 74,236 74,562 44,116 46,895 61,382 82,612 87,764 67,367
Delays as a percentage of scheduled flights 13.3 13.4 8.4 8.5 11.6 14.9 15.0 U

KEY: U = data are unavailable (i.e., not calculated).

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). 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). National Airspace System are delays and cancellations attributable to the national aviation system that refer to a broad set of conditions (e.g., non-extreme weather conditions, airport operations, heavy traffic volume, and air traffic control). Aircraft ariving 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. A security delay is a delay or cancellation caused by evacuation of a terminal or concourse, re-boarding of the aircraft because of a security breach, inoperative screening equipment, and/or long lines in excess of 29 minutes at screening areas.

The airlines required to report in 2003 were: Alaska Airlines, America West Airlines, American Airlines, American Eagle Airlines, ATA Airline (formerly doing business as American Trans Air), Atlantic Coast Airlines, Atlantic Southeast Airlines, 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, Bureau of Transportation Statistics, "Causes of Flight Delays," available at, as of March 2004.