Definition
A computer-generated warning produced by air traffic control radar systems in the terminal area (the airspace surrounding an airport) when two aircraft are predicted to come within unsafe horizontal or vertical separation of each other. The alert is displayed to the controller, who then issues instructions to resolve the conflict.
Plain English
An automatic warning that tells the air traffic controller when two aircraft near an airport are getting too close to each other, so the controller can step in and keep them apart.
Context Anchor
Seen in air traffic control and radar system discussions, especially for arrivals, departures, and other aircraft movement near busy airports.
Derivation
Terminal here refers to the airspace around an airport — the 'terminal area' — not an end point. Proximity comes from Latin proximus, meaning 'nearest.' The name describes exactly what the system does: it automatically alerts when aircraft proximity in the terminal area becomes unsafe.
Why Pilots Care
Reduces risk of runway incursions and traffic conflicts in the busy terminal environment.
Intuition Check
Do not read “terminal” as the airport building. Here it means the air traffic control area around an airport where aircraft are arriving, departing, and being managed.
Example Sentence 1
The controller's sudden turn instruction was triggered by an automated terminal proximity alert showing converging traffic.
Example Sentence 2
During low visibility, pilots listen for the Automated Terminal Proximity Alert to maintain safe separation.