Buy his book and perhaps all will be revealed!
Good points by Keg about gut feeling - obviously there's a sliding scale to be negotiated, with 'this looks really bad, let's get it on the ground as quick as we possibly can before it falls apart and kills us all' on one end, and 'don't rush into it and do something really stupid which kills us all' on the other.
It appears they trod the middle ground, as no doubt most people would, gathering information and processing it before deciding they were ready and it was time to land.