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GPWS -NORMAL DISPLAYS
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GPWS -MODE DESCRIPTION SUMMARY
General
This summary shows this information:
*
GPWS modes
*
Mode conditions
*
Aural messages for each mode
*
Lights or displays that come on.
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GPWS -MODE DESCRIPTION SUMMARY
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GPWS -SPEECH PROM
General
The speech PROM supplies aural messages when the mode detector detects an alert or warning condition.
The speech PROM also gives altitude callouts for selected radio altitudes.
Description
The speech PROM gives only one message at a time. If more than one message discrete comes from the mode detector, the speech PROM sends the message that has the highest priority.
The glideslope repetition rate circuit controls the repetition rate of the glideslope message.
The program pins select the radio altitude callout configuration.
Training Information Point
The GPWC stores these two aurals which are not related to the GPWC alert modes:
*
ENGINE FAIL
*
V1.
The GPWC makes these aurals come on when the GPWC receives a request from the AIMS.
The AIMS makes the ENGINE FAIL aural request when an engine fails, the airplane is on the ground, and the airplane CAS is more than 65 knots, but less than 3 knots below V1. V1 is the takeoff decision speed.
The ENGINE FAIL and V1 aurals do not come on during a GPWC test.
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GPWS -SPEECH PROM
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GPWS -ENVELOPE MODULATION
General
Some airports have unusual terrain clearances near their runways that cause false messages by the GPWS. Envelope modulation modifies specific alert and warning areas to prevent false messages.
Functional Description
The airports that need envelope modulation are in the GPWC memory and identified by their latitude and longitude. As the airplane approaches one of these airports, the GPWC looks at other airplane parameters to verify if an envelope modulation condition exists. The additional parameters are:
*
Radio altitude
*
Magnetic track
*
Glide slope deviation
*
Localizer deviation
*
Selected runway heading
*
Barometric corrected altitude.
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GPWS -ENVELOPE MODULATION
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GPWS -OVERRIDE CAPABILITIES
General
These override switches modify or cancel certain GPWS modes:
*
Ground proximity flap override switch
*
Ground proximity gear override switch
*
Terrain override switch.
The graphic shows these conditions:
*
Modes
*
Configuration of the flaps and gear
*
Effects of each override switch for the mode.
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GPWS -OVERRIDE CAPABILITIES
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GPWS -PFD AND MASTER WARNING LIGHT ANNUNCIATIONS
Master Warning Lights
The captain and first officer red master warning lights come on with a PULL UP or WINDSHEAR warning. The AIMS cabinets send a discrete to the warning electronic system (WES) to enable the lights.
PFD Warning Annunciations
The primary flight displays (PFDs) show these two GPWS messages:
*
Red PULL UP
*
Red WINDSHEAR.
The red PULL UP message shows for these conditions:
*
Mode 1 warnings
*
Mode 2 warnings
*
Terrain awareness warnings.
The red WINDSHEAR message shows a mode 7 warning.
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