Airline On-Time Performance and Causes of Flight Delays
Which airlines report on on-time performance
and, since June 2003, on the causes of flight delays?
On-time numbers are reported each month to the Department of
Transportation's Bureau of Transportation Statistics (BTS) by the 18 U.S. air carriers that have at least
1 percent of total domestic scheduled-service passenger revenues,
plus other carriers that report voluntarily. The reports cover nonstop
scheduled-service flights between points within the United States
(including territories) as described in 14 CFR Part 234 of DOT's
regulations.
The airlines required to report (Hawaiian Airlines reporting
voluntarily) are:
- AirTran Airways (FL)
- Alaska Airlines (AS)
- America West Airlines (HP)
- American Airlines (AA)
- American Eagle (MQ)
- ATA Airlines (TZ)
- Atlantic Coast Airlines (DH)
- Atlantic Southeast Airlines (EV)
- Comair (OH)
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- Continental Airlines (CO)
- Delta Air Lines (DL)
- ExpressJet Airline (RU)
- JetBlue Airways (B6)
- Northwest Airlines (NW)
- SkyWest Airlines (OO)
- Southwest Airlines (WN)
- United Airlines (UA)
- US Airways (US)
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What types of flight
delays are reported to BTS by the airlines?
Airlines that report monthly numbers of flight delays to the
BTS began reporting information
on causes of delays in June 2003. The airlines report the causes
of delays in five broad categories:
- Air Carrier: The cause of the cancellation or delay was due
to circumstances within the airline's control (e.g. maintenance
or crew problems, aircraft cleaning, baggage loading, fueling,
etc.).
- Extreme Weather: Significant meteorological conditions (actual
or forecasted) that, in the judgment of the carrier, delays or
prevents the operation of a flight (e.g. tornado, blizzard, hurricane,
etc.).
- National Aviation System (NAS): Delays and cancellations attributable
to the national aviation system that refer to a broad set of conditions
— non-extreme weather conditions, airport operations, heavy traffic
volume, air traffic control, etc.
- Late-arriving aircraft: A previous flight with same aircraft
arrived late, causing the present flight to depart late.
- Security: Delays or cancellations caused by evacuation of a
terminal or concourse, re-boarding of aircraft because of security
breach, inoperative screening equipment and/or long lines in excess
of 29 minutes at screening areas.
How were the reporting categories determined?
The U.S. Department of Transportation issued a final rule on
reporting the causes of flight delays on November 25, 2002 . The
final rule followed two years of consideration.
DOT formed an Air Carrier On-Time Reporting Advisory Committee
in August 2000 to consider changes to the current on-time reporting
system so that the public would have clear information about the
nature and sources of airline delays and cancellations. This task
force recommended the creation of a reporting framework for collecting
information about the causes of airline delays and cancellations.
In 2001, BTS conducted a pilot program with four airlines to test
the monthly reporting of causation. BTS based the final rule on
the recommendations of the task force, the results of its pilot
project, its outreach efforts to the aviation community and comments
received after a proposed rule was published in December 2001.
To view a copy of the rule, go to the Docket Management System
website, http://dms.dot.gov/,
and follow the instructions for viewing the documents in Docket
No. OST 2000-8164.
How is “weather” defined?
There is a fine line between some delays coded as ``Weather''
(extreme weather) and others coded as ``National Aviation System'' (non-extreme weather).
The purpose of the two categories is to identify the party or organization
in the best position to take corrective action. Delays or cancellations
coded ``Weather'' (extreme weather) cannot be reduced by corrective
action. Delays or cancellations coded ``NAS'' are the type of weather
delays that could be reduced with corrective action by the airports
or the FAA. Therefore, delays attributed to deicing are coded as
``Weather'' delays.
The regulation requiring the reporting of causes of flight delays
defines “extreme weather” as delays or cancellations caused by weather
conditions (e.g., significant meteorological conditions), actual
or forecasted at the point of departure, en route, or point of arrival
that, in accordance with regulatory standards and/or in the judgment
of the air carrier, prevents operation of that flight and/or prevents
operations of subsequent flights due to the intended aircraft being
out of position as a result of a prior delay or cancellation attributable
to weather."
How many flights are delayed by weather?
Weather delays are spread throughout the reporting system. The
airlines report some weather delays in a category called “extreme
weather.” Other weather delays are included in the National Airspace
System category. Adding the two numbers together gives a truer picture
of the impact of weather on flight delays.
Also, the “late arriving aircraft” category also includes weather
delays. The airlines are not required to report the causes of late-arriving
aircraft but these weather delays could be in the same proportion
as the weather-caused delays in other categories. The true picture
of the impact of weather on airline flights would consist of the
“extreme weather” delays plus the weather portion of the National
Airspace System category plus the weather portion of the Late Arriving
Aircraft category.
What flights does the reporting cover?
The rule requires carriers to report on operations to and from
the 31 U.S. airports that account for at least 1 percent of the
nation's total domestic scheduled-service passenger enplanements.
However, all reporting airlines have voluntarily provided data for
their entire domestic systems.
What airports does the reporting cover?
The 31 reportable airports are:
- Atlanta: Hartsfield (ATL)
- Baltimore/Washington: International (BWI)
- Boston: Logan International (BOS)
- Charlotte: Douglas (CLT)
- Chicago: Midway (MDW)
- Chicago: O'Hare (ORD)
- Cincinnati: Greater Cincinnati (CVG)
- Dallas-Fort Worth: International (DFW)
- Denver: International (DEN)
- Detroit: Metro Wayne County (DTW)
- Ft. Lauderdale: International (FLL)
- Houston: George Bush (IAH)
- Las Vegas: McCarran International (LAS)
- Los Angeles: International (LAX)
- Miami: International (MIA)
- Minneapolis-St. Paul: International (MSP)
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- Newark: Liberty International (EWR)
- New York: JFK International (JFK)
- New York: LaGuardia (LGA)
- Orlando: International (MCO)
- Philadelphia: International (PHL)
- Phoenix: Sky Harbor International (PHX)
- Pittsburgh: Greater International (PIT)
- Portland: International (PDX)
- St. Louis: Lambert (STL)
- Salt Lake City: International (SLC)
- San Diego: Lindbergh Field (SAN)
- San Francisco: International (SFO)
- Seattle-Tacoma: International (SEA)
- Tampa: Tampa International (TPA)
- Washington: Reagan National (DCA)
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How are flight delays calculated?
A flight is counted as "on time" if it operated less
than 15 minutes after the scheduled time shown in the carriers'
Computerized Reservations Systems (CRS). Arrival performance is
based on arrival at the gate. Departure performance is based on
departure from the gate.
For how long have airlines reported
on-time performance?
Airlines have reported on-time performance to the U.S. Department
of Transportation since 1987. Reporting was modified in 1995 to
include reporting of mechanical delays, which had not been included
in the original rule. Monthly reports are released in the Air Travel
Consumer Report.
What types of data are published?
The U.S. Department of Transportation publishes a monthly summary
of airline on-time performance, including causes of delay, in the
Air Travel Consumer Report ( http://airconsumer.ost.dot.gov/reports/index.htm
)
The Bureau of Transportation Statistics publishes a variety of
on-time and flight delay information.
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