Enhanced Ground Proximity Warning System (EGPWS) advanced system designed to alert pilots if their aircraft is in immediate danger of flying into the ground or an obstacle. The original GPWS concept relied on information from the air data system and radio altimeter. Enhanced systems use data from satellite systems and databases containing information on a digital elevation model (digital presentation of the terrain elevation features on a topographic map) and an aeronautical database.

 

A terrain awareness and warning system (TAWS) aims to prevent controlled flight into terrain. 

A TAWS works by using digital elevation data and airplane instrumental values to predict if a likely future position of the aircraft intersects with the ground.  The flight crew is thus provided with "earlier aural and visual warning of impending terrain, forward looking capability, and continued operation in the landing configuration.