This thread has lost its way unfortunately. It is full of bad advice and bad practices. I am very familiar with para dropping and operating turbines at DZ's - NOT above 13,000' but more usually 12,000'. To ignore the possibilities that lack of oxygen can bring is sheer madness and incrediby bad airmanship. Remember it is NOT allowed in the UK.
As for anyone removing the keys as a prank - the offender should be grounded never to jump again. Taking "spares keys" is NOT an argument and such an incident could easily lead to a crash.
Feel free to start another thread but Guppy will not be joining you.
Read the link above about hypoxia - its dynamite.
And by the way - swearing is not allowed PPRuNe. If you cannot debate without it don't post.
PPP