GPWS Flashcards
What is GPWS
Ground proximity warning system
Also knows as TAWS (terrain awareness warning system)
Prevents CFIT
What does a basic GPWS system do
Monitors closure rate
What does an enhanced GPWS system do (EGPWS)
Ability to predict the terrain ahead
Used a global terrain database stored
What are the GPWS inputs
Radio altimeter Airspeed Barometer altitude Aircraft configuration ILS glideslope deviation
What height does GPWS have a active system
Between 50- 2450ft radio alt
What is GPWS flap inhibit button
Stops “too low flaps” when trying to land in a non standard config
What is GPWS gear inhibit button
Stops “too low gear” warning when gear up landing is intended
What is GPWS terrain inhibit button
Inhibit terrain look ahead function (EGPWS)
What is a genuine alert / warning
Actual / real warning / threat
What is a nuisance threat / warning
System is operating to its correct specification but no threat = can ignore in Vmc
What is a false warning/ threat
Warning that is completely wrong
What is mode 1 GPWS
Excessive rate of descent
Alert = “sink rate, sink rate”
Warning “whoop whoop pull up”
What is GPWS mode 2
Excessive terrain closure rate
Alert “terrain terrain”
Warning “whoop whoop pull up”
What is GPWS mode 3
Altitude loss after take off or go around
Alert “don’t sink”
Disabled 1000ft above ground
What is GPWS mode 4 A
Unsafe terrain clearance with gear up
Warning >190 knots <1000ft = “too low terrain”
Alert <190knots <500ft “too low gear”
What is GPWS mode 4 B
Unsafe terrain clearance with flap up
Warning >150 knots <1000ft =“too low terrain”
Alert <150 knots <245ft = too low flaps
What is mode 5 GPWS mode
Descend below glideslope
Alert “glide slope”
1.3 does = soft alert
Full scale deflection = yells at you
What is mode 6 A GPWS
Altitude call out
Alert “minimums”
What is GPWS mode 6 B
Bank angle
Warning “bank angle”
What is GPWS mode 7
Windshear
Warning “windshear”
Armed below 1500ft rad alt
What is an alert
A caution which precedes a warning
What is a warning
A command which must be followed
What happens to TAWS is there is a inaccurate navigation system
Inaccurate TAWS ;
- map shift
a more common on older INS or IRS with no gps
GPWS part of system continues to function normally
What are EGPWS warnings based on
Time to impact
This is why some circling approaches and go-around a have limiting speeds
When does the warning for a EGPWS start
20/30 seconds from impact
What does the caution for EGPWS start
40/60 seconds from impact
On GPWS does black represent
> 2000 feet below
On GPWS does green represent
500-2000’ below
On GPWS does yellow / amber represent
Up to 2000’ above
On GPWS does red represent
> 2000’ above
What happens to the colours on GPWS when you enter the time restrictions to impact
Pickle colours change to solid colours
Only thing shown on ND is GPWS
What is terrain clearance floor (TCF)
Around nearest runway
Available for all runways >3500ft
Outer limit is up to 700ft and extends to infinite or where it meets another runway TCF
If floor penetrated “too low terrain”
What must the 2 classes of TAWS have
A and B
Must have forward looking terrain avoidance (FLTA) with suitable visual and aural alerts
What aircraft are required to have GPWS
> 5700kg
Or
9 passengers
Class A
