B737 GPWS Control Panel
BELOW Glideslope (G/S) light
On Panel P1 and P3
- The BELOW G/S light illuminates when the GPWS senses excessive deviation below the ILS or GLS glideslope or the FMC-generated flight path angle.
- Illuminated (amber) – below glideslope alert is active.
- Push – inhibits ground proximity GLIDESLOPE alert when below 1,000 feet radio altitude.
Inoperative (INOP) light
- Illuminated (amber) – GPWS computer malfunction or power loss.
- Invalid inputs are being received from radio altimeter, ADIRU, ILS receiver, IRS, FMC, stall management computers, DPC, or EFIS control panel.
Ground Proximity System Test (SYS TEST) Switch
- momentarily on ground:
- BELOW G/S and GPWS INOP lights illuminate
- TERR FAIL and TERR TEST show on navigation displays
- PULL UP and WINDSHEAR alerts illuminate
- GLIDE SLOPE, PULL UP, and WINDSHEAR aurals sound
- terrain display test pattern shows on navigation displays
- CAUTION TERRAIN aural sounds and TERRAIN caution
message shows on navigation displays. - AIRSPEED LOW (airplanes with AIRSPEED LOW aural).
- until self-test aurals begin, on ground, above indications always occur first, followed by these additional aurals:
- radio altitude based alerts
- bank angle alert
- approach callouts
- windshear alert
- look ahead terrain alerts
- system test inhibited in-flight.
Ground Proximity FLAP INHIBIT Switch
- FLAP INHIBIT – inhibits ground proximity TOO LOW FLAPS alert.
- NORM (guarded position) – Normal TOO LOW FLAPS alert active.
Ground Proximity GEAR INHIBIT Switch
- GEAR INHIBIT – inhibits ground proximity TOO LOW GEAR alert.
- NORM (guarded position) – Normal TOO LOW GEAR alert active.
Ground Proximity Terrain Inhibit (TERR INHIBIT) Switch
- TERR INHIBIT – inhibits look–ahead terrain alerts and terrain display.
- NORM (guarded position) – Normal terrain alerts and terrain display active.