How, precisely, has hypoxia been ruled out?
Noises of shouting, banging on the door, screaming from pax, clearly audible captain's voice from outside the FD - multiple sources show, IMHO, that Hypoxia can be ruled out BRD.
How, precisely, has incapacitation been ruled out?
Deliberate selection of an ALT below MSA and deliberate actions required by the F/O to keep the FD door locked out after the 5 mins are up - rules out his incapacitation BRD.
Precisely which actions have been established?
Who took them?
As described above - identifiable voice of the Captain on CVR outside the FD, examination of what sounds picked up by individual mikes allows for placement of those sounds.
You are right that little has been
precisely determined - but little rarely is. Many facts have simply been determined to be the
only plausible conclusions.
Many are understandably unwilling to accept this at face value. Many are also crying foul that info has been released this early in an accident investigation - a very unusual step.
But remember - this accident clearly seems not to have been an accident at all, and those conclusions have been able to be drawn pretty quickly and conclusively - which to my mind means different rules apply.
As for sources - all of this comes from what the French authorities have reported to be on the CVR, and I have no reason to doubt that.