TERPROM
TERPROM is a military navigation Ground Proximity Warning System (GPWS) employed on aircraft and missiles, which uses stored digital elevation data combined with navigation system and radar altimeter inputs to compute the location of an aircraft or missile above the surface of the Earth. It is also used as a warning system to prevent aircraft from flying too close to the ground. The name was originally derived from TERrain PROfile Matching but the acronym has now become a trademark in its own right.