On Judge Jeanine tonight, there was mention of Li-ion batteries in the cargo hold. Could be a game changer.
Suppose there is a fire, maybe caused by ruptured batteries, the pilot immediately turned around for emergency descent. Smoke fills the cabin and the fire knocks out all communication. The pilot abruptly climbs in attempt to put out the fire using very high altitude with depressuration. Thinking that works desends and they succomb to the toxic smoke after their oxygen is depleted. Last move, they set the 777 on autopilot. Plane flies for hours and runs out of fuel, or explodes because of the fire.
Plausible.
In an uncontrollable fire, a pilot will not climb “to put out the fire” - we will descend rapidly to land ASAP.
Still that’s no reason to turn off the transponder.