aterpster;
What about when the speed is at minimum for a given flap configuration, say whatever is required to fly the CTL downwind at 150 KIAS. Presumably, the aircraft was at 2510, msl, and had to clear terrain that topped out at 4,000-4,300, msl, or thereabouts.
(I don't think the terrain in that area was much above 3000', but that is immaterial.)
HundredPercentPlease's statement provides an important key to your question: "
The array of computers and sensors will give you every last ounce of performance available." This applies regardless of aircraft configuration. The available performance energy at slow speed, Config 3 may or may not be sufficient as an escape maneuver. A TAWS Caution of Terrain is approximately one minute's distance and a TAWS Warning is approximately 30 second's distance. Sixty seconds distance is plenty of time to climb 2000' in a GPWS escape maneuver; even 30" distance would be sufficient if the maneuver were done briskly. This is assuming no map-shift of course. I have read the arguments for GPS-linked EGPWS systems and have made the argument myself at my own airline to no avail...the SOP in the FCOM is to switch off the TAWS if NAV ACCURACY is LOW.
I think the aircraft was travelling faster than near the min-speeds for Config 3 as has been posited. I think the aircraft was at Config 2. Regardless however, we know that the TAS would have been slightly higher than the CAS, and, taking the wind information (albeit on the ground) from your post just above, there may have been a tailwind component, strong if they went straight ahead over the airport, stronger if they turned left, (NW), more of a crosswind than a tailwind if they turned right. I think the speed was closer to 180kts.
My reasoning is, by the FCOM, Config 3 is the normal Landing flap, although Config FULL is always available. Both Config 3 and 2 are Takeoff and Approach (maneuvering) flap settings, and Config 3 is also a Landing flap setting. Config FULL is only a Landing Flap. Although maneuvering at Config 3 is a normal procedure and is a plausible scenario here, "Landing flap", whatever the setting is, (3 or FULL), is not normally selected until established on final.
I'm thinking here of the distance travelled past the airport in poor vis; - In short, a possible loss of SA. Whether any of this is the case here or not, cannot be said until the recorders are read.
PJ2