Automatic Dependent Surveillance – Contract

ADS-C (Automatic Dependent Surveillance – Contract) is a surveillance technology where the aircraft avionics automatically transmit position, altitude, speed, and intent data to ATC via satellite data link under a 'contract' (agreement) between the aircraft and the ground system.

Unlike ADS-B (which broadcasts to all nearby receivers), ADS-C reports are sent only to the contracted ATC facility via SATCOM. It is the primary surveillance method for oceanic and remote airspace where radar coverage does not exist.

• Used extensively over the North Atlantic, Pacific, and polar routes
• Requires FANS (Future Air Navigation System) avionics and CPDLC capability
• Reporting intervals are configurable (periodic, event-driven, or on-demand)
• Enables reduced separation standards in non-radar airspace