Definition
A generic term used by ICAO to describe any ground-based system that provides air traffic services with the position, and where applicable other identifying information, of aircraft. It includes primary radar, secondary surveillance radar (SSR), Automatic Dependent Surveillance-Broadcast (ADS-B), Automatic Dependent Surveillance-Contract (ADS-C), and multilateration (MLAT) systems, or any comparable ground-based system used to deliver an air traffic service.
Plain English
Any ground equipment that lets controllers see where aircraft are. The ICAO term covers all the different technologies — radar, ADS-B, multilateration — under one umbrella name, instead of just saying 'radar.'
Context Anchor
Seen in international air traffic control, surveillance, and separation discussions, especially in ICAO-based procedures or glossaries.
Derivation
ATS stands for Air Traffic Services. 'Surveillance' comes from the French surveiller, meaning 'to watch over.' ICAO chose this broader term because newer technologies like ADS-B and multilateration also let controllers 'watch over' aircraft, even though they aren't radar.
Why Pilots Care
It gives controllers the real-time aircraft positions needed to maintain safe separation and manage traffic flow.
Grounding Statement
The key idea is that air traffic services are not just listening to pilots; they are using equipment that shows aircraft position and identity.
Intuition Check
Surveillance here does not mean video cameras or someone visually watching the sky. It means approved air traffic equipment that detects and identifies aircraft.
Example Sentence 1
In airspace served by an ATS surveillance system, the controller can issue radar-like vectors even when the underlying technology is ADS-B rather than primary radar.
Example Sentence 2
Modern ATS Surveillance Systems allow closer spacing of aircraft while maintaining safety margins.