Definition
The pilot's deliberate choice of where to attempt a forced or precautionary landing when continued flight is not possible, based on a comparison of available surfaces for survivability, controllability of the touchdown, and post-landing access to help.
Plain English
Picking the best available place to put the airplane down when you can no longer keep flying. You weigh the options in front of you and choose the one most likely to leave you and your passengers walking away.
Context Anchor
Seen in emergency landing training, especially when discussing what to do after engine trouble or when an off-airport landing may be needed.
Derivation
Terrain comes from the Latin terra, meaning land or ground. In aviation it refers to the surface features below the airplane — fields, water, trees, roads, slopes. Selection emphasises that this is an active choice, not whatever happens to be underneath you when the engine quits.
Why Pilots Care
Proper terrain selection greatly reduces the risk of injury and aircraft damage in an off-field landing.
Grounding Statement
If the airplane cannot make it to a runway, the pilot must look outside, compare the available ground areas, and commit to the one that offers the safest landing path.
Intuition Check
Terrain selection does not mean choosing the most open-looking area automatically. It means choosing the safest usable landing area after considering wind, surface, slope, obstacles, and how the airplane will stop.
Example Sentence 1
After the engine lost power, the pilot's terrain selection came down to a ploughed field on the left or a stretch of straight road on the right.
Example Sentence 2
Good terrain selection includes avoiding power lines and choosing a surface firm enough for the landing gear.