Definition
Any approved electronic system used by air traffic controllers to determine the position of aircraft, including primary radar, secondary surveillance radar (SSR), Automatic Dependent Surveillance-Broadcast (ADS-B), and Wide Area Multilateration (WAM). These sources feed aircraft position data to controllers' displays so they can provide separation and other ATC services.
Plain English
It's the technology ATC uses to see where aircraft are. This can be radar, or newer systems like ADS-B that track aircraft using GPS information broadcast from the aircraft itself.
Context Anchor
You may see this term in FAA material about radar services, aircraft identification, traffic separation, and airport surface monitoring.
Derivation
Surveillance comes from the French sur- ('over') and veiller ('to watch'), literally 'watching over.' In ATC, it captures the idea of controllers continuously watching aircraft positions, regardless of which specific technology supplies the picture.
Why Pilots Care
Determines whether you can receive radar vectors, flight following, or traffic advisories, and affects how accurately controllers can keep aircraft separated.
Intuition Check
Do not read “surveillance” here as spying or a person watching out a window. In this FAA use, it means an approved system that supplies position information to air traffic control.
Example Sentence 1
Outside of ATC surveillance source coverage, controllers must rely on pilot position reports to maintain separation.
Example Sentence 2
ADS-B has become the primary ATC surveillance source in many areas previously covered only by radar.