GPWS

Question 1

What’s the differnce between GPWS and EGPWS?

Answer 1

GPWS sees only down

EGPWS sees forward an down

Question 2

What are the GPWS modes?

Answer 2

1. Excessive descent rates
   Works below 2’450 ft
   “SINK RATE”
   “PULL UP”
2. Excessive terrain closure
   Warns when radio altidude is decreasing rapidly and there’s no excessive ROD
   “TERRAIN TERRAIN”
   “PULL UP”
3. Altitude loss after T/O
   Works from 50 ft. Starts when alt loss is 10% of altitude gained. A/c gains 500ft after T/O, a loss of 50ft will trigger warning
   “DON’T SINK”
4. Insufficient Terrain Clearence
   4A: During cruise. “TOO LOW TERRAIN” above 178 kts between 500 - 750 ft AGL
   4B: Or with gear not down. “TOO LOW GEAR” below 178 kts below 500ft
   4C: Or not in full flaps config. “TOO LOW FLAPS” below 148 kts and 170 ft
5. Descent below Glideslope
   Works below 925 ft radio alt and a/c is 1,3 dots FLY UP indication.
   “GLIDESLOPE”
   Soft warning below 925ft and 1,3 dot fly-up
   Hard warning below 300 ft and 2,0 dot fly-up
6. Advisory
   “MINIMUMS MINIMUMS” below/at 200 ft
   “FIVE HUNDRED”

Question 3

What are the inputs to the GPWS system?

Answer 3

• Radar altimeter
• Barometric rate of change configuration
• ILS
• Air Data Computer
• IRS