As more aircraft equip with ADS-B OUT–which broadcasts position, velocity, altitude and other information in unencrypted formats on easily received frequencies–business aircraft operators are concerned about whether they can continue blocking their aircraft from display on flight-tracking websites. While the FAA offers a way for operators to request blocking of particular aircraft from FAA radar data feeds, there currently is no physical means to block reception of mode-S transponder or ADS-B signals by a simple receiver.
Hobbyists are placing these receivers on roofs all over the world, connecting them to the Internet and sharing the resulting data feed, creating what in effect is an enhanced planespotter system. Flight-tracking providers FlightRadar24 and FlightAware actively solicit this data and also provide free ADS-B receivers to certain users to add this information to their traffic displays. However, both companies said they redact any registration information about blocked aircraft coming from ADS-B receivers or elsewhere.
Though big-player flight trackers are working with the industry and complying with block requests, there are other ways of obtaining this information, such as multilateration, according to FlightAware CEO Daniel Baker. There is also free PlanePlotter software that allows users to view information about aircraft movements around the world using data from hobbyists’ ADS-B receivers, multilateration and radar feeds, complicating tail-blocking efforts as more countries install multilateration systems or require aircraft to equip with ADS-B OUT.