Controlled Flight Into Terrain (CFIT)
Gulfstream G450 Abnormals
Figure: G450 SVS Terrain, from G450 Aircraft Operating Manual, §2B-06-50, figure 32.
The Bottom Line First: Pilot Reaction
There are two levels of Enhanced Ground Proximity Warning System (EGPWS) warnings in response to terrain: TERRAIN or PULL UP. The only difference in pilot response is that the TERRAIN warning does not include retracting the speed brakes. You should respond, however, in either case as given for a PULL UP:
While the G450 procedure leaves them out, don't forget to stow the speed brakes.
Had the crew of American Airlines Flight 965 at Cali done so, they might have lived.
If you remember anything, remember this:
- React immediately.
- Rotate 3 - 4° per second — rotating too quickly can stall the wing momentarily
- Look for VREF/V2 - 20 knots — the wing produces lift deep into the shaker — you should always leave the display controller on the FLT REF page for this (and many other) reasons.
Flight Path Vector
If your aircraft doesn't have synthetic vision and you control your flight department's budget, allow me to make a buying recommendation: synthetic vision offers the greatest safety advance for the dollar available today.
If you have synthetic vision, you should use it. If you are low to the earth with the stick shaker going off, wouldn't you like to trade your circa-1940 attitude indicator for this:
Figure: G450 Synthetic Vision, with a few of my crayons, from G450 Aircraft Operating Manual, §2B-06-50, Figure 32.
Why not just fly the flight path vector? That's what you do on an ILS, after all. Keep in mind it is an instantaneous readout of where the airplane is going, it will be jumping all around the place and if you chase it, you will be flying erratically enough to cost climb performance. Just smoothly fly the boresight as you would a "normal" airplane and watch how the flight path vector reacts. If it jumps into the terrain now and then, raise the boresight a little. Try this in the simulator, it only takes one try to understand why.
Gulfstream G450 Aircraft Operating Manual, Revision 35, April 30, 2013.