[Procyon]

The 777 is certified to fly to 43,000 feet because from that height the aircraft is able to safely descend to 12,500 feet altitude in case of cabin decompression before the passenger supplemental oxygen is depleted.

If it's true the aircraft was observed on radar at 45,000 feet, I will speculate that the pilot on his own oxygen staged a cabin depressurization, the passenger oxygen masks deployed but were depleted and everyone but the cockpit crew died. There is a supplemental portable oxygen tank for cabin crew but I don't know how long that lasted. Apparently in the Helios event a cabin attendant survived long enough to get into the cockpit after everyone else was dead but was unable to fly the aircraft.

[gandalftb]

Agreed, the limit switches on the cabin air outflow valves will limit the cabin pressure to about 14,000’ by going fully closed during an ascent.

The cabin leakage is about 1,000 feet per minute up to FL350. Above FL430 the leakage is much higher, the masks deploy but at that altitude there would only be a few minutes of oxygen. Incapacitation of the passengers would happen within minutes.

The pilot would be quite safe for an extended time.

[HANG THE EXPENSE]

I have heard the walk around bottles are good for 20 to 30 minutes max.