BendixKing KGP 860 - Manual (Page 10)

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Rev 5 Jul/2004 KGP 560/860 Pilot's Guide
AIRCRAFT ALTITUDE
In addition to the altitude information provided by the GPS, the KGP
560/860 GA-EGPWS uses uncorrected barometric pressure altitude
information from the aircraft’s encoding altimeter, blind altitude encoder
or transponder. This altitude information allows the system to do two
main tasks.
First, by using a special “derived-altitude” developed by Honeywell called
“Geometric Altitude”, the GPS and uncorrected pressure altitude infor-
mation is blended together by the system to provide accurate altitude
information, which is using the same Mean Sea Level (MSL) reference
as the terrain, obstacle and runway databases in the system. The
blending functionality of “Geometric Altitude” means it is much less sus-
ceptible to errors or malfunctions in the use of normal altimeter systems.
(The pilot is NOT required to enter an altimeter setting specifically for the
GA-EGPWS system).
Where aircraft are routinely operated in extreme weather conditions
(either hot or cold), Honeywell strongly recommends the optional temper-
ature input be used with the KGP 560/860 GA-EGPWS. This additional
factor in the blending formula of “Geometric Altitude” provides an even
more accurate vertical position to the system, and prevents serious dis-
crepancies between actual altitude and “Geometric Altitude” under
extreme temperature conditions, especially during rapid climbing or
descending flight profiles.
The second benefit of using “Geometric Altitude” in the system is that the
pilot will now have an independent monitor of altitude. The system can
detect an abnormal difference between “Geometric Altitude” and the
uncorrected pressure altitude. Optionally, the system can provide a
voice call-out and display a message to the pilot should such an
abnormal difference occur.
Geometric Altitude
Functions and Features