An audio declutter feature is active in the TAWS. It reduces the repetition of warning
messages.
The TAWS modulates the warning and alert envelope to avoid nuisance warnings or alerts at
airports with unique terrain conditions. The airport database provides detailed data of all
airports with a hard runway surface length greater than 620 m.
WARNING: To avoid unwanted alerts, TAWS must be Inhibited by the TAWS INHIB p/b
within 15 NM of take-off, approach or landing at an airport which is not
included in the airport database. This will deselect all TA WS functions but
will not effect the basic GPWS operation.
• In
hibit modes
All aural ground proximity warnings are inhibited when the pre-stall warning is active. A
guarded FLAP OVERRIDE p/b at the captain's MAIN INSTRUMENT PANEL is provided
to inhibit warnings in mode 4 caused by flap position; for example when a landing has to
be performed with less than normal flaps.
The glide slope warning can be inhibited when the aircraft is deliberately flown below the
glide slope during the final approach below 2000 ft RA. The mode automatically rearms
when 2000 ft RA is passed during a climb or 30 ft RA in a descent. The GS WARNING
INHIB button is located at the captain's MAIN INSTRUMENT PANEL.
• Steep approach
The Sleep Approach capability can be (de)activated mariually via the STEEP APPROACH
p/b at1he captain's MAIN INSTRUMENT PANEL. The P/B will only function in flight, and
will be automatically reset in case of a landing or go-around. Activation of this capability
adapts GPWS warning mode 1 to allow for higher sink rates during approaches on a
steep ILS glideslope (4.0-5.5 degrees).
Mode description
The EGPWS comprises the basic GPWS plus TAWS functions.
BASIC GPWS functions
The basic GPWS is active between 50 feet and 2450 feet Radio Altitude and comprises six
warning modes:
• Mode 1: Excessive descent rate.
• Mode 2: Excessive closure to terrain.
• Mode 3: Altitude loss after take-aft or go-around.
• Mode 4: Inadvertent proximity to terrain.
• Mode 5: Excessive deviation below the ILS glide slope.
• Mode 6: CalI-outs during approach for s
elected DH, a pre-determined Radio
Altitude and bank angle.
A detailed table concerning all warnings/alerts is presented at the end of this paragraph.
Fokker 50 - Flight Navigation Instruments
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