Part of the Federal Aviation Administration’s (FAA) recent modernization efforts require that all aircraft above a certain size carry a transponder, constantly broadcasting its location. This data is useful for keeping routes uncluttered, reconstructing what happened in a crash, and generally managing the flow of humans in the sky.
It is also an invaluable tool for those seeking to track surveillance flights.
John Wiseman is a Disney Imagineer who, in his off time, tracks aerial surveillance flights. Using ADS-B Exchange, a noncommercial flight tracking site that plots broadcast flight data on a map, he has created “Advisory Circular,” a collection of city-specific Twitter bots that look for circular flights over cities, which may indicate surveillance.