MAJOR U.S. AIR CARRIER ON-TIME PERFORMANCE
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Major U.S. Air Carrier On-Time Performance (monthly data, not seasonally adjusted)
Flights Not Arriving On-Time (monthly data, with underlying trend)
The number of flights not departing or arriving on time, cancellations, and
diversions are measures of service quality. These indicators are strongly seasonal
and are affected by weather and heavy demand in winter and summer months, respectively.
| Number of scheduled flights |
514,448 |
448,322 |
| Scheduled flights percent change from same month previous year |
0.32 |
-12.85 |
| Percent of flights not arriving on time |
24.86 |
21.36 |
| Change of flights not arriving on time from same month previous year |
-9.46 |
-3.51 |
| Percent of flights not departing on time |
21.29 |
18.40 |
| Change of flight not departing on time from same month previous year |
-8.43 |
-2.89 |
| Percent of cancelled flights* |
2.98 |
1.71 |
| Change of cancelled flights from same month previous year |
-0.01 |
-1.27 |
| Percent of diverted flights** |
0.32 |
0.23 |
| Change of diverted flights from same month previous year |
-1.22 |
-0.09 |
* Also counted in flights not arriving or departing on time.
** Also counted in flights not arriving on time.
NOTES: The current value is compared to the value from the same period in the
previous year to account for seasonality. Data for American Eagle was included
starting in January 2000. Percent changes from January 1999 to January 2000 were
calculated based on data excluding American Eagle. Aloha Airlines, which reported
on-time statistics for October 2000 through November 2001, has been excluded to
retain comparability.
The data cover the 10 largest U.S. air carriers. A scheduled operation consists
of any nonstop segment of a flight. The term "late" is defined as 15 minutes after
the scheduled departure or arrival time. A cancelled flight is one that was not
operated but was listed in a carrier's computer reservation system within seven
calendar days of the scheduled departure. A diverted flight is one that left from
the scheduled departure airport but flew to a destination point other than the
scheduled destination point.
A trendline has been provided for flights not arriving on-time. The trend has
been calculated through a statistical procedure called Structural Modeling, in
which the time series under study is decomposed into seasonal, trend and irregular
components. For further information on this statistical procedure, see: S.J. Koopman,
et al., Structural Time Series Analyser, Modeller and Predictor (STAMP), London:
Timberlake Consultants Ltd. , 2000
The dramatic changes in the September 2001 data reflect the impact of the terrorist
attacks on Sept. 11, 2001, on aviation, including several days in which commercial
air operations were suspended.
Certain flights originating at O'Hare airport and operated by American Airlines
(181 flights in April) and United Airlines (256 flights in April) between April
24, 2002 and May 8, 2002 are not included in the calculations due to the participation
of these carriers in a pilot test program for enhanced baggage screening. A list
of affected flights affected is available from BTS.
SOURCE: U.S. Department of Transportation, Bureau of Transportation Statistics,
Airline Service Quality Performance data.
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