GPWS -MODE 5 DESCRIPTION

General
The GPWC gives a mode 5 alert when the airplane is too far below the glideslope during a front course approach when the landing gear is down. Mode 5 does not operate during back course approaches.
Description
Mode 5 alerts can occur between 30 and 1000 feet. The aural alert message is GLIDESLOPE GLIDESLOPE and the ground proximity light comes on.
The ground proximity glideslope inhibit switch inhibits or cancels mode 5 alerts.
If the deviation below the glideslope increases, the volume of the aural message increases.
The message repeats faster as the terrain gets closer, or if the glideslope deviation increases.
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GPWS -MODE 5 DESCRIPTION

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GPWS -MODE 5 OPERATION

General
Mode 5 alerts can occur between 30 and 1000 feet radio altitude. Mode 5 arms during these conditions:
*
The airplane terrain clearance is less than 1000 feet

*
The gear is down

*
The glideslope signal is captured.

These LRUs supply inputs for mode 5 operation:
*
Left, right, and center radio altimeter transceivers

*
Left ILS receiver

*
AIMS cabinets.

The GPWC uses this data to detect mode 5 alerts:
*
Glideslope deviation

*
Selected runway heading

*
Magnetic track

*
Gear position.

Low level audio occurs below 1000 feet down to 30 feet when the deviation is more than 1.3 dots.
Normal level audio occurs below 300 feet when the deviation is more than 2 dots.
The interval between messages is normally 5.15 seconds. At 300 feet, the message repeats at a faster rate for a larger glideslope deviation.
Operation
Push the ground proximity glideslope inhibit switch to inhibit or cancel mode 5 aural and visual alerts.
If you push the switch before mode 5 alerts begin, you inhibit the aural and visual annunciations.
If you push the ground proximity glideslope inhibit switch during a mode 5 alert, you cancel the aural and visual annunciations.
When you inhibit or cancel the alert, you cannot activate it again unless the airplane leaves the mode 5 alert area or you operate the landing gear.
The mode detector uses the inputs to look for an alert condition. If there is an alert condition, the mode detector sends a discrete to turn on the ground proximity light. The discrete goes to the speech prom to make the alert aural.
The alert aural also goes to the WES which sends it to the aural warning speakers.
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GPWS -MODE 5 OPERATION

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GPWS -MODE 6 DESCRIPTION

General * The airplane goes from takeoff to approach and the radio altitude is higher than an altitude callout. In this case, only The GPWC gives mode 6 aural callouts when the airplane those altitude callouts that are lower than the current radio altitude come on as the airplane descends.
descends through selected altitudes with the gear down. A program pin selection determines the callout configuration. Mode 6 supplies only callouts. There are no visual indications.
Description
The GPWC receives inputs from:
*
Left, right, or center radio altimeter transceivers

*
AIMS cabinets

The GPWC uses this data to determine mode 6 alerts:
*
Radio altitude

*
Gear position

*
Program pin selection.

The program program pins do these functions:
*
Enable the callouts

*
Select the callout configuration

*
Select low volume or normal volume for the callouts.

Mode 6 callouts come on only once. These are the two ways to reset mode 6 callouts:
* The airplane climbs through 1,000 feet of radio altitude while
on approach.

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GPWS -MODE 6 DESCRIPTION

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GPWS -MODE 7 DESCRIPTION

General
The GPWC gives mode 7 warnings when windshear conditions are present in takeoff or approach. The thresholds depend on flap position.
　
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