Quote:
Originally Posted by damien b
Agree with Nigel on the Physics and g forces being felt by the passengers. They would have hit the ceiling on the pitch down movement, whilst when the aircraft pitched up - depending on the g loading they may have been pushed back into their seats for a brief moment.
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I need to articulate my analysis in a little more detail to see if it makes a difference to yours and Nigel's responses. Imagine that you were in a lift that suddenly accelerated downwards rapidly. You'd hit your head on the ceiling of the lift. If it then reversed direction just as suddenly, you'd be slammed into the floor.
Now think of the a/c as pivoting around the fulcrum of the wings like a see saw, so that in a sudden climb the displacement of the rear of the aircraft is like the suddenly descending lift - the inertia of the unrestrained mass of people and service carts will tend to make them rise in relation to the descending portion of the fuselage at that point.
The physics is complex but my thinking is that the aircraft was not climbing under power - this was an uncommanded climb during stable cruise, so the kind of acceleration forces that push you back in your seat on take off would not have been present when the sudden elevator displacement was initiated.
It may need a bit of a crash test dummy experient to see which forces take precedence. If the aircraft had no forward movement component, you would get the see saw analogy. My suspicion is that in level cruise the sudden movement had the same effect. I agree that under horizontal acceleration the physics would be different, as they would be if my see saw were on a platform that was undergoing additional acceleration forces. Then you need to study all the vectors to see how they work out.
With CAT, the sudden downward displacement of the fuselage is what makes unrestrained people contact the cabin ceiling - I'm positing the same effect in the aft of the cabin from a sudden pitch up during stable cruise.
In the second movement sequence recorded on the FDR the 8.4 degree pitch down and descent to my mind would have more likely created almost zero G for everyone on the a/c and that would not have resulted in the injuries being so concentrated in the aft section of the cabin.
Would love to get more views so let's hear what others think.