I really HAVE to say something about hypoxia.
If you are involved in a decompression at altitude you will NOT feel dizzy, ill or euphoric. You will become unconscious without realising anything is wrong with you.
You absolutely MUST get the oxygen mask on immediately it drops and you MUST fit yours before assisting the kids.
Basil, You are correct. Pilots in PNG used it to quieten unruly highlanders on long flights to Moresby in unpressurised aircraft. Take it to 17 - 18 thousand and the pax go to sleep.
If the 777 did go to 40 - 45 thousand for a few minutes, whilst unpressurised, anyone not on oxygen would probably be dead.
As far as where the 777 is right now, the only certainty: - it is not in the air.
Prayers for the pax and families.