Automatic Dependent Surveillance – Broadcast (ADS-B)

Automatic Dependent Surveillance – Broadcast (ADS-B) is a surveillance technology in which an aircraft determines its own position via GNSS and continuously broadcasts it — along with identity, altitude, velocity, and other data — to ground stations and other aircraft. ADS-B is “automatic” (no interrogation needed), “dependent” (relies on GNSS), and “surveillance” (supports ATC tracking).

ADS-B Out vs. ADS-B In

• ADS-B Out: Aircraft broadcasts its own position — allows ATC to track without radar; required in designated airspace
• ADS-B In: Aircraft receives ADS-B data from others — enables traffic awareness (TIS-B) and weather datalink (FIS-B) in the cockpit; not yet mandated

ADS-B in Canada

NAV CANADA has deployed an extensive ADS-B ground network providing surveillance coverage in areas where radar is unavailable — including northern Canada, the Labrador coast, and oceanic approaches. Transport Canada is implementing ADS-B Out requirements on a phased basis.

Advantages Over Radar

• Extends surveillance to radar-dark areas (mountains, ocean, Arctic)
• Position updates approximately once per second vs. radar’s 4–12 seconds
• Lower ground infrastructure cost
• Enables cockpit traffic awareness via ADS-B In

On the TC Written Exam

Know the difference between Out (broadcast, ATC tracking) and In (receive, cockpit awareness); that it depends on GNSS position; and that it extends coverage to non-radar environments.

Related Terms

See also: Transponder, GPS, RADAR.