My sense of the human factors is;
I see some similarities in the ABX cargo DC8 positioning flight where the crew was performing stall tests at night in and out of weather.
The tests went fine until their attitude decayed (deeper than expected into stall) and they failed to realize their rapidly unwinding altitude. Their response was methodolical and calm (senior pilot training another pilot) right up until the "terrain" warning voice.
To me it looked like they lost sensory awareness to what is just a temporary aberation and what is the highest priority response.
my gut feeling tells me that if they were able to see a horizon or had considered the rapidly unwinding altitude they would have reacted differently.