Honeywell MK VI - Manual (Page 17)

Honeywell
MK VI MK VIII EGPWS Installation Design Guide
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1.5.5 OAT Senso r
The EGPWS uses a separate OAT sensor (Outside Air Temperature) to measure outside air temperature on
aircraft that do not have another compatible source of outside air temperature. Outside Air Temperature is used
by the EGPWS along with pressure altitude in the Geometric Altitude computation. If Outside Air Temperature is
not available, Geometric Altitude is computed using pressure altitude and GPS Altitude with a corresponding
reduction in accuracy. Honeywell engineers have determined that the reduction in accuracy is small because
the GPS Altitude is the strongest element in the computation.
Geometric Altitude is computed by the EGPWS to reduce or eliminate errors potentially induced in corrected
barometric altitude by temperature extremes, non-standard altitude conditions, and altimeter miss-sets.
Geometric Altitude also allows continuous EGPWS operation in QFE environments without crew intervention.
1.5.6 Smart Cabl e (PCMCIA Interface)
The EGPWS Smart Cable (part number 951-0386-001) is a removable PCMCIA card interface. The Smart
Cable is compatible with Honeywell supplied ATA style PCMCIA cards for use with MK VI and MK VIII EGPWS.
The purpose of the Smart Cable in the EGPWS system is for upload of software and databases and also for
download of EGPWS Flight History. The Smart Cable loading operation will closely emulate that of an ARINC
615 Data Loader. (Reference Figure 1-1 MK VI/MK VIII EGPWS SMART CABLE)
FIGURE 1-1 MK VI/MK VIII EGPWS SMART CABLE