BOX 5-B
Airline Service Quality Performance (ASQP) Data and Air Travel
Time Indexes
To
calculate these indexes, the Bureau of Transportation Statistics used ASQP data
that airlines report monthly on both scheduled and actual flight times (based
on gate-departure and gate-arrival). The data cover all domestic nonstop flight
segments flown by
U.S.
carriers with at least 1
percent of passenger revenues in the previous year. The ATTVI is measured using
standardized deviations of actual air travel time from its average value.
Deviations are weighted to increase the variability index more for extreme
deviations than for small deviations. Both the ATTVI and the ATTI are designed
to control for changes in carriers, routes, and time of day in order to improve
comparability over time. Airports included in the analysis are those that
ranked in the top 50 (by passenger enplanements of all large certified
carriers) for at least one year between 1990 and 2004. Analysis of the
time-of-day for departure is based on four periods: morning offpeak (before 9 a.m.); mid-day peak (between 9
a.m. and 3 p.m.); evening peak (between 3
p.m. and 9 p.m.); and evening offpeak period (after 9 p.m.). Analysis of flight
distance is based on three categories: 500 miles and less; 501 to 1,000 miles;
and more than 1,000 miles.
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