The Bureau of Transportation Statistics (BTS) quarterly Passenger Origin and Destination Survey provides the data for the ATPI. Through this survey, BTS collects data on a 10 percent sample of airline itineraries. Each sample observation comprises a fare value (actual fare paid, including tax), a sequence of airports and carriers, and other details of an itinerary traveled by a passenger or group of passengers.
BTS computes the ATPI series using a price index methodology similar to that used by other federal statistical agencies. Although the ATPI is computed using a tested index methodology, the effective application of this methodology to the airlines' data is still under development, and it was still considered a research series at the time this report was prepared. BTS updates the ATPI quarterly; see http://www.bts.gov/.