The general aviation sector has contributed significantly to the overall growth of the aviation industry. Fleet mix and operations information is important for the analysis of both the safety and the environmental and economic impact of general aviation activity. Factual data on the impact of environment and safety is particularly important, given the scarcity of airport improvement funds and the strong stakeholder engagement that often occurs when airport investments are evaluated. The research presented herein evaluates Mode S short and extended squitter data collected from three general aviation airports over a one-month period. This article demonstrates that by utilizing the unique ICAO code present in Mode S records in the United States, ICAO identification can be used as a primary key for retrieving information from publicly available databases, permitting the determination of aircraft type and engine models. An aircraft operation type with the corresponding fleet mix information can thus be estimated at non-towered airports. The techniques reported here are also useful in monitoring the increase in aircraft compliant with the FAA’s January 1, 2020 mandate for ADS-B out to operate in large portions of the national airspace system. For the three Indiana airports studied, the proportion of ADS-B transponder messages received ranged from approximately 29% at the Terre Haute Regional Airport (KHUF) to 79% at the Purdue University Airport (KLAF)
