What frequency is used for ADS-B transmission as per the ICAO international standard?

The correct frequency used for ADS-B (Automatic Dependent Surveillance–Broadcast) transmission, as per the ICAO (International Civil Aviation Organization) international standard, is 1090 MHz. This frequency is specifically designated for transponder responses and ADS-B information exchange among aircraft and ground stations, allowing for improved situational awareness and surveillance capabilities in aviation.

The use of 1090 MHz is significant because it is a globally recognized frequency in aviation for surveillance purposes, enabling both civil and military aircraft to operate effectively. This frequency supports a range of functions, including the transmission of critical flight information such as position, velocity, altitude, and intent.

Other frequency options presented do not align with the established international standards for ADS-B. Frequencies like 800 MHz and 950 MHz are not designated for aviation use, while 1200 MHz, although sometimes associated with certain aviation systems, is not utilized for ADS-B transactions. Thus, 1090 MHz is the established and widely accepted standard essential for ADS-B operations around the world.