Originally Posted by
Sir Niall Dementia
As an exercise it is one that makes for a sweaty shirt, there was a Greek airliner that decompressed a few years ago, a steward on a portable oxygen bottle got into the cockpit and took one of the seats (both pilots were unconscious) the steward held a ppl, if he had yelled for help on the radio the outcome may have been different, it is believed he disconnected the auto-pilot and lost control of the aircraft;
If you are talking about Helios (which I believe you are as I'm not aware of any other remotely similar occurrences) the cabin crew member was actually a CPL holder.
I believe he was former Greek special forces, which was how he had managed to endure the hypoxia much better than others, once pax oxygen ran out he went on to the O2 cylinders.
From what I remember the aircraft went out of control due to flameout of one engine as a result of fuel exhaustion, not because AP was disconnected. He was unable to recover (due to the handling characteristics at altitude, exacerbated by thrust asymmetry and lack of B737 knowledge), but the second engine flamed out due to fuel exhaustion before the aircraft eventually crashed.