82046-PG-B1
ST3400H PILOT’S GUIDE
Page 7-1
7 GPWS
ALERTING
The ST3400H contains a Ground Proximity Warning System separate from
the FLTA alert system. The GPWS is a downward looking alert capability
which generally uses the radar altimeter as an alerting source.
The GPWS alerts could be considered as a backup system if FLTA was not
available (such as if GPS position was unavailable) or the helicopter was
hovering.
NOTE:
GPWS alerting, with the exception of Mode 5 Glideslope, is not
operational without a Radar Altimeter installed.
7.1
Mode 1 – Excessive Rate of Descent
A “SINK RATE” Caution Alert is generated when the aircraft height above
terrain is below 500’ AGL and is accompanied by a high rate of descent. If
the descent is not arrested a “PULL UP” Warning Alert is generated.
Figure 7-1 GPWS Mode 1 Alerts
7.2
Mode 2 – Not Implemented
This “Terrain Closure Rate” alert is a fixed-wing mode and not supported
in Helicopter TAWS.
7.3
Mode 3 – Descent after Takeoff
A “DON’T SINK” Caution Alert is generated if the aircraft climbs past
and then descends below 95’ while in the Normal Sensitivity mode (75’ if
operating in the Low Sensitivity mode) immediately after take-off. This
alert may be cancelled by pressing MUTE.
Figure 7-2 GPWS Mode 3 Alert
