"Re seeing values, feeling acceleration "...the crew should have realized that."
This might be a reasonable assumption without the effect of startle, but where sensory awareness is disrupted and automatic responses triggered due to surprise, then inability to realise is to be expected."
I meant something and did not express it very clearly I think. Here is what I meant :
Say you're in steady level flight and you loose 400ft in less than 5 seconds.
The only way this can happen is if you feel gigantic vertical acceleration. Maybe something like 0G for 2.5s and 2G for 2.5s.
I'm not gonna make a calculation but you see the idea.
So, since the crew did not feel such gigantic (relatively speaking) load factors, it must be because they did not actually lose 400ft in less than 5s.
It was only an altimeter artifact.