Hostile environment
urn:aero:airm:1.0.0:ContextualModel:ATMBusinessTerms:Hostile_environment
An environment in which: a) a safe forced landing cannot be accomplished because the surface and surrounding environment are inadequate; or b) the helicopter occupants cannot be adequately protected from the elements; or c) search and rescue response/capability is not provided consistent with anticipated exposure; or d) there is an unacceptable risk of endangering persons or property on the ground.
Source:
ICAO