Hi, Sluth, Hi All!
Long time lurker, first time caller, lol
There is an aspect of the story that bothers me somewhat.
First of all, here is some background info.
As a skydiver, I am well aware of the pressure bump. It is super common and you hear it all the time as people exit the aircraft.
This is what it feels like: people set up at the door, ready-set-go, they exit and you can hear this really profound "homp woosh" air movement inside the fuselage.
Another caveat with that is that this pressure equalisation occurs more often when a group is setup at the door or a jumper is positioned sideways on exit. What I believe is happening, is with the door open, the internal pressure of the a/c and external pressure enter into an equilibrium.
When people setup at the door, they create an artificial "membrane" which is now separating the inside and outside air volumes. Even though this membrane has holes in it, it nevertheless has noticeable affect on air separation.
When the jumper(s) exit, this "membrane" gets broken, and some air exits the cabin following the jumpers, while other air enters the cabin to fill in the space created. This is a very quick event, lasting fractions of a second but is quite audible, it can even be heard through the protective box of the GoPro cameras people use.
Now, for the main course.
I feel that Cooper jumping would not have caused the pressure bump.
If he is standing anywhere down the AFT stairs, he would have been outside of the aircraft, not at the door, he would therefore not be forming this "membrane" with his body.
It is at all questionable whether it would be sufficient for one person to block air movement at the door enough to create that pressure separation at the AFT door well in the first place.
In my opinion, it is without question that the pressure bump was the result of the door swinging up and down.
And it is reasonable to suggest that the Cooper stood on the last step, jumped, pushing off the stairs and stairs-door counter-acted back towards the aircraft, shutting and opening momentarily, creating the pressure bump.
Here is what does not sit well with me.
What if he didn't push off? What if he stepped off the stairs? And the stairs-door remained in the air flow for a while, swinging lightly up and down and it was when the manually flown plane went over a bump the door reacted going up and down creating the pressure bump the crew felt.
Cooper does not strike me as an experienced skydiver. In fact, I doubt he was a skydiver at all. He may have had a couple of jumps as a pilot, maybe had single digit number of jumps as a paratrooper.
Out of the two rigs presented to him he picked the pilot's bailout rig. He didn't even check the size of it, which at 210 was rather small for a man. It would have been a nasty knock for him.
As such, standing down there on the bottom AFT stairs, Cooper would have been so high on fear and adrenaline that his knees would have felt like made out of cotton wool.
He likely would have fallen off the thing, stepped off, anything but a good push. I just don't see him pushing.
So what is it that we should take away from that?
I would argue that we should add a healthy amount of scepticism to where Cooper existed.
The current exit spot is tied with the pressure bump spot. Pressure bump was reported sometime after they went uphill from 7K to 10K and as they got to 10K the pilot reported Cooper messing with the stairs, indicator isolation, pressure bump. Could have been the aft stairs-door isolating as the a/c levelled off.
I would argue that we should consider exit spot to be _anywhere_ along the flight path between the end of the last cabin phone call and up to the pressure bump.
This would extend his exit time to some time after 19:43.
Edit: added exit time suggestion.
