GPWS

Question 1

What descent rates are considered excessive with regards to GPWS at low altitude?

Answer 1

2’500 fpm below 2’500 ft

1’500 fpm below 1’500 ft

Question 2

How many modes does GPWS have?

Answer 2

7

Question 3

What is the difference between GPWS and EGPWS?

Answer 3

EGPWS can look ahead to see terrain

Question 4

What does the different GPWS colors mean with TERRAIN selected on the ND?

Answer 4

Dotted green = -2’000 to -500 ft
Dotted amber = -500 to +2’000 ft
Dotted red = +2’000 or above
Dotted magenta = No terrain data available

Solid Amber = Look-ahead Terrain Caution Alert
Solid Red = Look-ahead Terrain Warning Alert

Question 5

Which alert have priority nr 1, 2 and 3with GPWS warnings?

Answer 5

Priority 1 = Mode 7 “Windshear x3”
Priority 2 = Mode 1 “Pull up” (sink rate)
Priority 3 = Mode 2 “Pull up” (terrin closure)

Question 6

Describe GPWS Mode 1

Answer 6

Mode 1 = EXCESSIVE DESCENT RATES
Activates below 2'500 ft AGL
Has two protection envelopes:
1. "SINK RATE"
2. "PULL-UP"

Question 7

Describe GPWS Mode 2

Answer 7

Mode 2 = EXCESSIVE TERRAIN CLOSURE
Activates when terrain is within 2'000 ft of the aircraft
Has two protection envelopes:
1. "TERRAIN TERRAIN"
2. "PULL -UP"

Question 8

Describe GPWS Mode 3

Answer 8

Mode 3 = ALTITUDE LOSS AFTER TAKE-OFF
Works from 50 ft altitude
Activates when altitude loss is 10% of altitude gained.
(A 50 ft altitude loss after 500 ft altitude gain)
Warning is : “DON’T SINK”

Question 9

Describe GPWS Mode 4

Answer 9

Mode 4 = INSUFFICIENT TERRAIN CLEARENCE. Alerts below 1’000 ft with “TOO LOW TERRAIN”
Mode 4A: “TOO LOW GEAR” below 500 ft AGL and less
than 190 kts
Mode 4B: “TOO LOW FLAPS” below 245 ft AGL kts and
less than 160 kts
Mode 4C: “TOO LOW TERRAIN” Active during takeoff and alerts when the terrain is rising more steeply than the aircraft is climbing

Question 10

Describe GPWS Mode 5

Answer 10

Mode 5 = DESCENT BELOW GLIDESLOPE
Works below 925 ft AGL and 1.3 dots Fly Up indication
Soft warning = Below 925 ft and below 1,3 dots
Hard warning = Below 300 ft and below 2,0 dots
Will reset below 50 ft, above 1’900 ft and when selecting a VOR frequency

Question 11

Describe GPWS Mode 6

Answer 11

Mode 6 = ADVISORY CALLOUTS
"MINIMUMS"
"FIVE HUNDRED"
"50, 40, 30 RETARD"
"BANK ANGLE"

Question 12

With a terrain caution, what is the projected time to impact?

Answer 12

40-60 seconds

Question 13

With a terrain warning, what is the projected time to impact?

Answer 13

20-30 seconds

Question 14

Memory items for GPWS warning?

Answer 14

A/P OFF
A/T OFF
Max thrust, retract speed brakes
Roll level and pitch up to 20 deg
Don’t change config until clear of terrain

Question 15

Why don’t we retract the flaps or gear during a GPWS warning maneuver?

Answer 15

it can cause distraction from the precise flying needed during the maneuver. Gear doors opening will cause extra drag which will degrade climb performance

Question 16

What is the accuracy, in feet, of EGPWS?

Answer 16

25 ft