No pressurization on T/O
Having twice experienced no pressurization on T/O - on 757 due icing up of the outflow valve - not only are there warnings for this, though I am not familiar with the 73, surely, surely! the crew would have noticed something strange immediately. I recall recognising the problem on rotation, not when the jungle fell on the pax. And that is not because I was a brilliant pilot (I wasn't, I don't think), but because I am a human being and not used to my ears being punished the way they were. Even if Jaipur was hot and high, it's not that high and there would have been going on ten minutes before the masks fell. We obviously do not have the whole story and so it can only be conjecture at this point.
Prober