One other comment before I have to go.
A lot of people have been going on about the 45,000 feet thing. I'm a bit dubious about that.
As you go up in altitude, the air becomes thinner. You rely on air passing over the wings to generate lift. The less dense the air, the less lift you generate. The aeroplane at the beginning was still quite heavy (with fuel). It would not have been able to climb to 45,000 feet at thst stage because it simply could not generate enough lift. If ithad tried, it would have stalled (stall on a plane is not like stall in a car - it's nothing to do withthe engine. Stall simplymeans there's not enough air passing over the wings to stay in the air any more).
A really, really good practical example of this is the Air France crash.
The pilot tried to climb out of trouble - he put the aircraft in a climb and put the engines to full power. The aeroplane would not climb. It stalled and carried on stalling more or less all the way down til it hit the Atlantic.
I think that this plane is in the same situation - i.e. too heavy to climb to 45,000 feet no matter how much power you put on. In any case, 45,000 feet is above the maximum cruising altitude approved for the 777. Even so, the aircraft would likely stay pressurised but I don't know if it could maintain the normal cabin pressure in the cabin (the cabin is pressurised to the equivalent of 8,000 feet). I suspect not but I don't know because it's never been done to the best of my knowledge.
I also read someone mentioning a theory about the doors being opened at 25,000 feet to 'get rid of passengers'. That isn't possible if the aircraft hasn't suffered a decompression. The doors won't open much above about 14,000 feet. Aeroplane doors work like a plug. As the aeroplane climbs, the pressure outside drops. The pressure inside is maintained at 8,000 feet. The pressure inside pushes the dorr into the aircraft structure, like a plug, and seals it. No human being could open that door above about 14,000 feet (they're designed to be opened at that height because some airports in the Himalayas are that high).
Got to disappear now for a bit.