Plain English Meaning
A safety system in the aircraft that watches how close you are getting to the ground and shouts a warning if it thinks you are about to fly into it.
Full Definition
An onboard alerting system that monitors an aircraft's height above terrain using radio altimeter data and other inputs, and provides the flight crew with aural and visual warnings when the aircraft is in a flight configuration that risks an unintended collision with the ground.
Context Anchor
Pilots encounter this term in aircraft equipment descriptions, cockpit warning discussions, and accident-prevention training involving flight near terrain.
Derivation
Proximity comes from a Latin word meaning “nearest” or “very close.” In this term, it points to the system’s job: warning the crew when the aircraft is too near the ground for the .