Definition
A flight technique, typically automated, in which the aircraft maintains a constant height above the ground by continuously adjusting its altitude to match the rising and falling terrain below. The aircraft climbs over hills and descends into valleys to stay at a set distance above the surface, rather than at a fixed altitude above sea level.
Plain English
Flying so the aircraft stays close to the ground at a steady height, going up and down with the shape of the land beneath it.
Context Anchor
Seen in references to low-altitude operations, especially military training or aircraft systems designed to fly close to the ground.
Derivation
Terrain comes from the Latin terra, meaning earth or land. In aviation, it points to the shape of the ground below the aircraft, which is the reference the aircraft is following.
Why Pilots Care
Reduces pilot workload and improves safety when flying close to the ground over uneven terrain during low-level operations.
Intuition Check
Terrain following does not mean following a route across the ground. It means changing altitude to stay a selected height above the terrain.
Example Sentence 1
The crew engaged terrain following to stay 500 feet above the surface as they crossed the ridges.
Example Sentence 2
Terrain following allowed the helicopter to stay low and undetected through the valley at night.