Purpose
ATA produces the Airline Cost Index to monitor trends in the cost of inputs (e.g., labor, fuel, food, aircraft ownership, airport landing fees, insurance, utilities, interest) to the provision of air service over time. The various indices also facilitate comparisons among the components themselves and between airline costs and broader economic indicators. Long-term cost trends are important determinants of airfares.
While the Airline Cost Index includes the traditional measure of unit cost--cost per available seat mile (CASM)--the index values themselves are the superior bellwethers of the price of inputs to production. CASM can mask the true cost of an input because it also reflects changes in productivity over time.
Release
ATA publishes the Airline Cost Index and restates prior quarters as data becomes available from DOT. It reflects all U.S. passenger airlines filing complete reports for the corresponding quarter. In addition to the summary below, you can view any of the following:
Note: Data prior to 1990 excludes airlines with annual revenues less than $100 million. Results for a given quarter are typically available within 120 days of its completion (i.e., Jan. 31, 2007, for 3Q06).
*Although interest is a non-operating expense, it is factored into the composite cost index to capture the role of debt in the provision of air service. It is not included in the composite cost per ASM or share of operating expenses.
Notes
The vast majority of the Cost Index is derived from quarterly financial and operational information collected by DOT (principally Form 41 reports), and historical data may be restated as warranted. Neither the Cost Index nor its components are seasonally adjusted because 1) users may find seasonal fluctuations of great interest and 2) leaving the data unfettered allows users to impose adjustments of their own choosing. Consequently, quarter-to-quarter movements in certain indices may be driven in part by the seasonality of the variables used to compute them. Each category of expenses in the Cost Index is described on our Definitions page.