Traffic information services-broadcast (TIS-B) traffic snooping

A method for furnishing an indication that an ownship aircraft is within coverage of air traffic information transmitted by an air traffic control ground station, the method comprising:

• receiving a transmission from an air traffic control ground station, the transmission comprising air traffic information and a client list comprising identification addresses of aircraft included in the air traffic information;
• determining whether the ownship aircraft is within a range of a second aircraft;
• determining whether the second aircraft is included in the air traffic information by comparing the identification address of the second aircraft with the identification addresses in the client list;
• and
• causing an indication to be provided that the aircraft is within coverage of the air traffic information transmitted by the air traffic control ground station when the second aircraft is determined to be included in the air traffic information and the ownship aircraft is determined to be within the range of the second aircraft.

An ADS-B system configured to for operation in an ownship aircraft, the ADS-B system comprising:

• a receiver assembly operable to receive a transmission from an air traffic control ground station, the transmission comprising Traffic Information Services-Broadcast (TIS-B) air traffic information and Traffic Information Services-Broadcast (TIS-B) service status list comprising International Civil Aviation Organization (ICAO) addresses of aircraft included in the Traffic Information Services-Broadcast (TIS-B) air traffic information;
• and
• a processing system operable to:
• determine whether the ownship aircraft is within a predetermined range of a second aircraft;
• determine whether the second aircraft is included in Traffic Information Services-Broadcast (TIS-B) air traffic information by comparing an International Civil Aviation Organization (ICAO) address of the second aircraft with the International Civil Aviation Organization (ICAO) addresses in the Traffic Information Services-Broadcast (TIS-B) service status list;
• and cause an indication that the aircraft is within coverage of the Traffic Information Services-Broadcast (TIS-B) air traffic information transmitted by the air traffic control ground station to be provided when the second aircraft is included in the Traffic Information Services-Broadcast (TIS-B) air traffic information and the ownship aircraft is within the predetermined range of the second aircraft.