> Trouble is, there are multiple separate radios they could use, both HF and VHF. Or they could apparently have taken a second to activate the 777's Emergency

> Trouble is, there are multiple separate radios they could use, both HF and VHF. Or they could apparently have taken a second to activate the 777's Emergency Locator Transponder, powered by its own battery and with its own hardwired, non-computerised switch circuit to the cockpit. You could imagine the aircraft accidentally flying (and transmitting over SATCOM) for hours with no other communications if there was some kind of crisis that completely cut off the pilots' (and passengers') ability to use the flight controls for the whole time (quite possibly by killing them) without damaging plane's systems much overall. Hypoxia or smoke inhalation seem plausible. Some kind of fire that completely destroyed the instrument panel without spreading too much further sounds vaguely possible. (IIRC at least one of the pilots had a habit of smoking while flying.) Surely both pilots couldn't somehow have locked themselves out of the cockpit behind the security door? The problem is that such a scenario is hard to square with a flight path that apparently included multiple changes of course and altitude long after any initial cockpit emergency https://news.ycombinator.com/item?id=7420894 https://news.ycombinator.com/item?id=7420894 .