Very theoretical, but I would suggest that initiating a descent, the nose-over would cause a reduction in required lift (curved flight path) and AoA would therefore be reduced, increasing the margin to stall (effectively temporary increasing the altitude of coffins corner).
Immediately thereafter, once established in the descend (straight downwards flight path, lift and weight again balanced out, with the original AoA), the aircraft would be out of coffins corner and stall speed would start to reduce.
Hence, it would in theory only be dangerous to maintain the altitude and either increase or decrease speed. I don't see any reason why flying up to coffins corner with a perfectly accurate speed, level off and curving/descending back out would not be possible. ...in an ideal theoretical world.
The "coffin" in coffins corner probably more likely comes from someone trying to either establish it or break it during test flights in the '50'ies where no computer models where available to make accurate predictions.
Last edited by cosmo kramer; 18th May 2012 at 01:36.