The ADP was developed using the most reliable sources of public data available: U.S. Department of Transportation Form 41 (U.S. DOT Form 41) from the Bureau of Transportation Statistics (BTS), and relevant filings to the Securities and Exchange Commission (SEC).

Consistent with airline industry practice, U.S. DOT Form 41 data is used to analyze aircraft and employee productivity, operational performance and other significant operational statistics. The SEC filings are the primary source of financial statistics.

The project provides transparent documentation of data sources and analytical methodologies for each data series. In all cases, the ADP discloses the specific data sources, quantitative methods, and assumptions used in the analysis. The time series of data provided here (beginning in 1995) better enables the user to make estimates or forecasts. More importantly, a long time series provides the breadth of information necessary to give the analysis proper historical context.

The ADP includes validation processes as an integral part of all phases of data collection and compilation, processing and analysis, and conducts appropriate quality evaluations of the statistical or financial information. For example, for the Form 41 and the SEC data, the major line items in the income statements of each were compared, and it was determined that - with few exceptions - the data is comparable. In cases in which obvious errors in the data can be traced back to the original Form 41 data products, cells are highlighted to alert the user that the output appears suspicious. The ADP does not attempt to correct for errors in the Form 41 data, instead choosing simply to alert the user that such an issue exists.

The ADP has made extensive efforts to aggregate all aspects of the data, applying the same analysis and calculations to each carrier and metric in order to standardize results and comparisons across airlines. For instance, in the case of aircraft type, we group aircraft by small narrow body (150 seats and less), large narrow body (151 seats and more) and wide body (two aisle aircraft). This helps to eliminate some of the issues when comparing data across multiple carriers, some of whom report their data in different ways.

To ensure the utility of information, every effort has been made to include general-purpose statistical and financial information and analysis designed to meet a variety of anticipated user needs. A glossary of common airline-related terms is also available. That said, users of this site are encouraged to vet each calculation and form their own conclusions regarding data comparisons.

Users also are encouraged to provide feedback regarding their information needs, as well as their ideas for new statistical and financial information and/or data that could be included in future analysis.