Abnormal Procedures - Honeywell MK VI Pilot's Manual

Abnormal
Procedures
Mode 1
Excessive
Descent
Rates
Mode 3
Altitude
Loss After
takeoff
Mode 5
Descent
Below
Glideslope
54
Partial system deactivation or compensation can be accomplished
for abnormal procedures as follows:
If steep approaches are to be performed (4º or greater) EGPWS
STEEP APPROACH should be enabled and selected for these oper-
ations (typically selected by a cockpit switch). When active, Mode
1 alerts are desensitized (biased 500 FPM for the caution and
200 FPM for the warning threshold) to compensate for normally
higher descent rates for these types of operation, eliminating
related unwanted alerts. If implemented with an alternate action
cockpit switch, this requires manual deactivation. Alternatively, a
momentary cockpit switch may be used, which can be cancelled
by pressing the switch again, or will automatically reset when the
aircraft lands or a go-around is initiated.
Additionally, Mode 1 can be desensitized by selecting the FLAP
OVERRIDE switch (GA only, not Turbofan). This permits poten-
tially higher descent rates resulting from flaps not being set to the
landing position during approaches. A 300 FPM bias is applied to
both the caution and warning thresholds. This bias is automati-
cally deselected below 50 feet AGL. Steep Approach has priority
over Flap Override if selected simultaneously.
Selecting Flap Override (GA only, not Turbofan) increases the al-
lowable altitude loss after takeoff. Mode 3 alerts are desensitized
(as a function of altitude) when the FLAP OVERRIDE switch is
activated. This is used to eliminate unwanted Mode 3 alerts if op-
erating at low altitude after takeoff. Flap Override is automatically
deselected below 50 feet AGL.
Mode 5 Glideslope alerts can be manually canceled when below
2000 feet Radio Altitude by pressing the G/S CANCEL switch
(commonly part of the amber caution annunciators "BELOW
G/S or "GPWS"). This is typically selected when an unreliable
Glideslope is expected or when maneuvering is required during
ILS final approach. The G/S Cancel is automatically reset follow-
ing landing or if the aircraft climbs above the 2000 feet.
Some aircraft may be configured with a G/S INHIBIT switch. This
switch is separate from the one discussed above but also results
in inhibiting Mode 5 alerting. This switch is intended for selec-
tion during back course approaches to eliminate unwanted alerts
that may result.
060-4314-000 • Rev. C - May 2004
MK VI & MK VIII EGPWS Pilot Guide