"A deep stall is NOT irrecoverable."
Oh YES IT IS, mate; and I have one dead friend to prove it.
You might want to tell the bloke who flew the NASA Schweizer in the deep stall regime over twenty times. That's right, at least twenty entries into and recoveries from deep stalls. Irrecoverable...NO, IT ISN'T.
AF447 was put into and held in a stable deep stall. If they had recognised this fact they may have had enough time to recover. The sad thing is they did not recognise it and held it in a deep stall for over three minutes.
You understand the difference between a deep stall and locked in deep stall?