Definition
Published instrument procedures and pilot techniques designed to keep an aircraft safely clear of terrain and obstacles during departure, en route, approach, and missed approach phases of flight. These include charted minimum altitudes, prescribed climb gradients, specific flight tracks, and missed approach instructions that, when flown correctly, guarantee required obstacle clearance.
Plain English
The published routes, altitudes, and climb requirements that keep you from hitting mountains, towers, or other obstacles when you cannot see them — for example, when flying in clouds.
Context Anchor
Seen during instrument approach planning, missed approach review, departure planning, and any briefing where nearby terrain or obstacles could affect the safe flight path.
Derivation
Terrain comes from Latin terra, meaning earth or land. Procedure comes from Latin words meaning to go forward. Together, the phrase points to planned steps for moving safely in relation to the ground, not just a general idea of being careful.
Why Pilots Care
Following these procedures prevents controlled flight into terrain, which is a leading cause of fatal accidents in low-visibility conditions.
Grounding Statement
Picture approaching an airport at night near mountains: the procedure tells you which path and altitude keep the airplane away from the ground you may not be able to see.
Intuition Check
Do not read terrain avoidance procedures as simply “look outside and avoid the ground.” In this context, it means following specific planned altitudes, paths, and actions designed to keep the aircraft clear of terrain.
Example Sentence 1
Before departing the mountain airport in low visibility, the pilot reviewed the terrain avoidance procedures published for the departure, including the required climb gradient.
Example Sentence 2
On the arrival, terrain avoidance procedures called for climbing to 4,000 feet until past the high terrain east of the airport.