This glossary is written for virtual airline and flight simulation use within Virtual Air Canada Airline. It is not intended as a real-world aviation reference.
GPWS/EGPWS
(Enhanced) Ground Proximity Warning System
The Ground Proximity Warning System is an avionics safety system designed to alert flight crews when the aircraft is in dangerous proximity to terrain or is in an unusual flight configuration that could lead to a controlled flight into terrain (CFIT) accident. Classic GPWS uses parameters such as radio altitude, barometric altitude rate, airspeed, gear position, and flap configuration to generate aural and visual warnings categorized into seven standard modes. These cover situations such as excessive descent rate, excessive terrain closure rate, altitude loss after takeoff, unsafe terrain clearance with landing configuration not set, and excessive below-glide-slope deviation.
Enhanced GPWS (EGPWS), also known as Terrain Awareness and Warning System (TAWS), adds a forward-looking terrain database that allows the system to predict conflicts with terrain ahead of the aircraft, not just directly below it. EGPWS continuously compares the aircraft’s position (from GPS), altitude, and flight path against a worldwide terrain and obstacle database. When a conflict is detected, it generates alerts earlier than classic GPWS - typically 60 seconds or more before impact - and displays a color-coded terrain map on the navigation display showing the surrounding terrain relative to the aircraft’s altitude. Mountainous regions, instrument departures, and oceanic descents in areas with abrupt terrain changes are scenarios where EGPWS provides critical advance warning.