System Radalt and GPWS

Question 1

Radalt Component/location

Answer 1

• Receiver/transmitter (avionics rack)
• Indicator
• Antenna system (most have 2, allows for continuous transmission/reception) (Under fuselage)

Question 2

Radalt numbers

Answer 2

• Cockpit: 10 foot increments above 200 feet, 5 feet increments below 200 feet
• Nav console: 10 foot increments
• Used by GPWS, Flight Guidance Computer (FGC), Air Data Computer (ADC), Flight Data Recorder (FDR)
• Up to 2500ft AGL

Question 3

GPWS inputs

Answer 3

• radio altimeter (altitude and decision heights)
• No.1 ADC (airspeed&altitude rate)
• No.1 glideslope receiver (glideslope deviation)
• Proximity Switch Electronics Unit (landing gear and flap position discrete)
• Stall warning computer (GPWS inhibited under near stall conditions to avoid distracting pilots)

Question 4

GPWS modes

Answer 4

Mode 1: excessive sink rate
Mode 2A: Excessive Closure Rate
Mode 2B: Excessive Closure Rate on Landing Approach
Mode 3: Altitude Loss after Take-off
Mode 4A: Proximity to Terrain, Gear up
Mode 4B: Proximity to Terrain, Flaps Up (Can be cancelled)
Mode 5: Descent Below Glideslope (Can be canceled)
Mode 6: descent below Radio Altitude DH