*
Longitude
*
Altitude
*
Vertical speed
*
Date
*
Time (UTC)
*
Ground speed
*
True track
*
Integrity of data
*
Sensor status.
Instrument Landing System (ILS)
The GPWC receives this data from the left multi-mode receiver (MMR):
*
Glideslope deviation
*
Localizer deviation
*
Selected runway heading.
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GPWS -INTERFACE
Warning Electronic System (WES)
Audio signals from the GPWC go to the warning electronic units (WEUs). The WEUs send the audio to the aural warning speakers.
Landing Gear Panel
The landing gear panel has these functions:
*
Terrain override switch
*
Ground proximity gear override switch
*
Ground proximity flap override switch
*
Ground proximity glideslope inhibit switch
*
Ground proximity light.
The GPWC sends an alert discrete signal to the GPWS landing gear panel to turn on the GND PROX light.
Traffic Alert and Collision Avoidance System (TCAS)
The GPWC sends a discrete to the TCAS computer to inhibit TCAS advisories that may conflict with GPWS aural messages.
Program Pins
Seventeen program pins connect to six GPWS lamp drivers. The connections are at terminal blocks on the E1-4 shelf in the main equipment center (MEC). When the airplane powers up, the lamp drivers turn on and off one at a time to read the program pin connections. These connections make up the GPWS configuration. The non-volatile memory (NVM) stores this configuration. The configuration determines such parameters as:
*
Airplane type
*
Mode 6 callouts
*
High or low audio volume.
Weather Radar (WXR) System
The WXR receiver-transmitters (RTs) sends predictive windshear (PWS) data to the GPWC to inhibit lower priority GPWS alerts.
The GPWC sends a discrete to the WXR RTs to inhibit lower priority PWS alerts.
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GPWS -INTERFACE
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GPWS -DISPLAY RELAY INTERFACE
Purpose
The ground proximity warning computer (GPWC) and the weather radar (WXR) receiver-transmitters (RTs) send display data that shows on the navigational displays (NDs). Four terrain select relays control which data shows on each ND.
Relay Power
The terrain select relays gets 28v dc from the TERRAIN DISPLAY circuit breaker on the P11 overhead circuit breaker panel.
Relay Interfaces
The GPWC connects to all terrain select relays with terrain display data buses. The WXR RTs connect to all terrain select relays with weather display data buses.
The terrain select relays connect to the AIMS cabinets with data buses. The AIMS cabinets show the data on the NDs.
Relay Control
With weather radar selected, the normal relay position lets weather radar data show on the NDs. When you select TERR on either EFIS control panel (CP), a terrain select ground signal energizes the two on-side terrain select relays. This allows the terrain data to show on the on-side display. Push the TERR switch again and the on-side relays deenergize. The display then shows weather radar data, if selected.
Relay Monitor
The GPWC monitors the terrain select relay positions for faults.
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GPWS -DISPLAY RELAY INTERFACE
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GPWS -GROUND PROXIMITY WARNING COMPUTER
Purpose
The ground proximity warning computer (GPWC) compares the airplanes flight profile, flap and gear position, and terrain clearance to determine if an alert condition exists.
Description
The enhanced GPWS function contains a worldwide terrain database. It compares airplane position, track, and speed with this database to find if there is an alert condition. Terrain data shows on the navigation displays (NDs).
The enhanced GPWS function also contains an airport database. This database contains terrain information for all hard surface runways 3500 feet or longer. GPWS compares airplane position and runway location to find if there is an alert condition.
Physical Description
The ground proximity warning computer (GPWC) is a two MCU chassis and weighs seven pounds. Forced cooling air is not necesary.
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