KTA 970/KMH 980 Pilot’s Guide
Rev 2
006-18273-0000
EGPWS Functions and Features
39
GA-EGPWS FUNCTIONS AND FEATURES
AIRCRAFT POSITION
The GA-EGPWS uses GPS information from either an aircraft-installed
GPS receiver, or an internal GPS receiver contained in the GA-EGPWS
computer itself. It is good for the pilot to be aware of the actual position
source being used by the system, as the internal GPS is not used for
navigation of the aircraft.
GPS signals arrive at an antenna on the aircraft and are then processed
by the GA-EGPWS computer to provide both horizontal (lateral) and ver-
tical position (altitude) information. This position in space is then com-
pared to the terrain, obstacle and runway database information con-
tained in the GA-EGPWS computer to produce a “virtual” picture which
can then be displayed to provide Situational Awareness for the pilot.
Other GPS information such as true track, groundspeed, vertical velocity,
N/S and E/W velocity, and signal accuracy measurements are also
processed by the GA-EGPWS computer to provide a complete picture of
not only the aircraft position in three dimensions, but also an excellent
picture of the aircraft’s flight path.
This total package of information is then used to provide the Terrain
Display for the pilot, and to provide alerting and warning functionality to
protect the pilot and passengers from possible conflicts with terrain,
known obstacles, and other scenarios associated with the dangers of
CFIT.
