ADS-B — Automatic Dependent Surveillance — Broadcast

ADS-B — Automatic Dependent Surveillance — Broadcast

ADS-B is transforming air traffic management by replacing or supplementing radar with a GPS-based broadcast system that is more accurate, cheaper to deploy and capable of providing coverage in areas beyond radar range — oceans, mountainous terrain and remote regions.

How ADS-B Works

Equipped aircraft continuously broadcast a signal containing: ICAO 24-bit aircraft address (Mode S transponder code), GPS-derived latitude, longitude and altitude, groundspeed and track, aircraft identification, and equipment status. Ground stations and other ADS-B equipped aircraft receive these broadcasts directly.

ADS-B Out vs ADS-B In

ADS-B Out: the aircraft broadcasts its own position to receivers. Mandatory in most controlled airspace in the US (2020), EU (2020) and increasingly worldwide. ADS-B In: the aircraft receives broadcasts from other aircraft and ground stations — enables cockpit situational awareness and traffic avoidance (CDTI).

ADS-B and Flight Tracking

The public availability of ADS-B receivers has enabled global flight tracking networks such as Flightradar24 and FlightAware. These networks aggregate ADS-B data from thousands of volunteer receivers to provide near-real-time global flight tracking.

Coverage Gaps

ADS-B ground receivers provide excellent coverage over land but limited coverage over oceans. Space-based ADS-B (Aireon system, hosted on Iridium NEXT satellites) extends global coverage, closing the oceanic surveillance gap that contributed to the prolonged search for MH370.