MODE 4: Flight into terrain when not in landing configuration
Flight Into Terrain When Not in Landing Configuration is active in cruise and descent phases
of flight when below 1000 feet AGL and not in landing configuration. Mode 4 is active
whenever mode 3 is inactive.
NOTE:
Mode 3 and Mode 4 cannot be active at the same time.
An alert occurs when the aircraft is operated too close to the ground with the landing gear
retracted or when the TAWS computer determines that the aircraft is in landing configuration
with less than landing flaps. These alerts are derived from radio altitude and airspeed and
are independent of closure rate. The “TOO LOW TERRAIN”, “TOO LOW GEAR” and “TOO
LOW FLAPS
” aural alerts are generated and the TERR caution annunciator is illuminated
when the appropriate envelopes are penetrated.
Mode 4A envelope is active during cruise and approach when the landing gear is up. Mode
4B is active during cruise and approach when landing gear is in landing mode and flaps are
not in landing configuration. If landing with flaps not in landing position, the FLAP OVRD can
be enabled to disable the MODE 4B callout.
Fokker 50 - Flight Navigation Instruments
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