Definition
An onboard system that uses the aircraft's position, altitude, and ground speed, combined with a stored database of terrain and obstacles, to alert the pilot when the aircraft is approaching rising ground or an obstacle that could result in a collision. It provides both forward-looking warnings and visual displays of terrain relative to the aircraft.
Plain English
A safety system that knows where the ground and obstacles are, watches where the aircraft is heading, and warns the pilot if the aircraft is getting too close to the ground or about to hit something.
Context Anchor
You encounter this term in aircraft equipment descriptions, avionics checks, instrument flying, night flying, and operations near rising terrain.
Derivation
“Terrain” comes from the Latin “terra,” meaning “earth” or “land.” That helps because this system is specifically concerned with the land and obstacles below or ahead of the aircraft, not with traffic or weather.
Why Pilots Care
Reduces the risk of controlled flight into terrain, one of the leading causes of fatal accidents in general aviation.
Grounding Statement
If the airplane’s present or predicted path gets too close to terrain, the system warns the pilot in time to climb or change course.
Intuition Check
Do not read “awareness” as meaning the pilot is simply paying attention. Here, it means the aircraft system is actively comparing the airplane’s path with terrain information and warning the pilot when the path becomes unsafe.
Example Sentence 1
On approach into the mountainous airport, the TAWS issued a 'Caution, terrain' alert, prompting the crew to verify their altitude against the approach plate.
Example Sentence 2
During the night approach the pilot watched the Terrain Awareness And Warning System display for any proximity alerts.