Ground proximity warning system
The United States Federal Aviation Administration (FAA) defines GPWS as a type of terrain awareness and warning system (TAWS).
As a result of these studies and recommendations from the U.S. National Transportation Safety Board (NTSB), in 1974, the FAA required all large turbine and turbojet airplanes to install TSO-approved GPWS equipment.
Older TAWS, or deactivation of the EGPWS, or ignoring its warnings when an airport is not in its database,[9] still leave aircraft vulnerable to possible CFIT incidents.
A computer then keeps track of these readings, calculates trends, and will warn the flight crew with visual and audio messages if the aircraft is in certain defined flying configurations ("modes").
If there is a dramatic change in terrain, such as a steep slope, GPWS will not detect the aircraft closure rate until it is too late for evasive action.
EGPWS introduces the Terrain Clearance Floor (TCF) function, which provides GPWS protection even in the landing configuration.
The occurrence of a GPWS alert typically happens at a time of high workload and nearly always surprises the flight crew.
[citation needed] In commercial and airline operations, there are legally mandated procedures that must be followed should an EGPWS caution or warning occur.
A smaller and less expensive version of EGPWS was developed by AlliedSignal (now merged with Honeywell) for general aviation and private aircraft.
[22] For fast military aircraft, the high speed and low altitude that may frequently be flown make traditional GPWS systems unsuitable, as the blind spot becomes the critical part.
[24] On May 5, 2016, a military GPWS called Automatic Ground Collision Avoidance System (Auto-GCAS) equipped aboard an F-16 was activated after a trainee pilot lost consciousness from excessive G forces during basic fighter manoeuvre training.
In an approximately 55 degree nose down attitude at 8,760 ft (2,670 m) and a speed of 750 mph (1,210 km/h), the Auto-GCAS detected that the aircraft was going to strike the terrain and executed an automatic recovery, saving the pilot's life.
