Crash landing and Emergency landing

Crash landing noun - An emergency landing under circumstances where a normal landing is impossible (usually damaging the aircraft).

Emergency landing and crash landing are semantically related. In some cases you can use "Emergency landing" instead a noun phrase "Crash landing".

Emergency landing noun - An unscheduled airplane landing that is made under circumstances (engine failure or adverse weather) not under the pilot's control.

Crash landing and emergency landing are semantically related. Sometimes you can replace phrase "Crash landing" with "Emergency landing", this phrases are similar.