Quick summary of events - please amend as necessary.
1. On take off, one of the AoA vanes is damaged.
2. 2 seconds after take off, stick shaker activates, resulting in understandable nose down pitch to gain speed.
3. Speed trim gives nose down trim inputs, as is usual - so trimmer is automatically trimming, as usual.
3. After flaps up MCAS becomes active, and gives large trim down - like a super speed-trim system.
Pilots may think this is normal speed-trimming.
(MCAS is using data from one sensor, which it should not be able to do.)
4. While sorting out the perceived stall situation, MCAS give two huge trim forward commands, half of which is wound back
(ending in a trim of 2.5 units, which is about 2.5 units more forward than usual)
5. Pilots are struggling with control, and turn off stab trim system. Some 50kg of force is needed to keep nose up.
6. If an attempt to engage autopilot was made it would be unsuccessful, as it cannot be engaged with stick pressure applied.
7. It is likely that manual trimming was attempted. But the manual trimmer will not work at these speeds and trim settings
(the trimmer is jammed at 2.5 units, with full back elevator pressure applied.)
8. It is decided to reengage the electric trim system, so they can re-trim.
9. Trim system is reengaged, and two small trim-backs are made, to solve the out of trim situation.
10. But MCAS gives another huge dose of forward trim, wrenching the control column out of their hands, and pinning them to the roof.
(it gives negative 0.5 g).
11. Control column is pulled full back, but cannot control the pitch, which continues to lower to -40 degrees.
12. Aircraft impacts ground.
Having tried this in the sim, I am surprised that full back pressure on the control column gave no response in pitch attitude. The sim did give a slow but positive response, although it took both pilots with maximum force to get a response and that response would be too slow in most circumstances. But on the real airplane, it looks like a stab-trim position of 1 unit at high speed renders the aircraft completely uncontrollable, and a crash inevitable. (They would understand that electric trim was faulty, and manual trim is not available at these trim settings.)
Silver