Airliner missing between Malaysia and Cambodia/Vietnam, terrorism possible

[Biggus]

Wouldn't the flight time tend to disqualify the parts of the arc closest to the latest known sighting, unless of course the aircraft doubled back at some point?

Not enough open source data to make the call on this. It could be anywhere along that arc, plus or minus 500nm, assuming ACARS remained pinging the satellite for as long as the aircraft remained intact. I would assume that it was closer to the Kazakhstan end than the Myanmar/Laos end.

What is nearly feasible is entering Chinese airspace over Myanmar where I'd expect the air search radars to be the weakest, and fly on the north side of the defences through western China.

That would be quite an accomplishment, given the extremely rugged and isolated terrain along the northern arc. Even for a fully resourced government it would be an expensive and time-consuming task. These are also not permissive environments for either air or ground movement, and to pull it off without alerting local authority (unless of course local authority is complicit) would be a real challenge.

It would be a nearly unthinkable accomplishment. We're talking about a very well prepared makeshift runway in as you say extremely rugged terrain with quantities of fuel that would take literally months to transport and then store on site, with a team of people who know what they're doing in regards to ground power, fuelling, approach guidance and marshalling, not to mention several hijackers who are intimately familiar with approaches to very basic airstrips in the incredibly difficult flying conditions native to the areas we're looking at. All the while, avoiding air search radars and any and all outside contact with the world, verbal, electronic, visual or otherwise.

It's not very likely.

Assuming a hijack, I'd guess the most probable scenario is a hijacking gone bad, meaning whatever events did not go according to plan and the plane crashed. If whoever did this actually has managed to get the plane on the ground, undetected, and is preparing it for further use... that would be disconcerting, as it would suggest an extraordinarily competent, organized, well prepared group, the kind that is a lot more common in the movies than in real life.

I'm not anywhere near ready to accept that the aircrew were involved in the hijacking, if a hijacking is what has occurred. The Captain is political and well educated, but we're talking I-want-more-democracy political, not America-is-the-Great-Satan political. He evidently loved his job, he (like thousands of other pilots) had a pretty incredible home simulator setup which the media seems to think is some sort of indicator of suspicion (because obviously nobody in the media has that sort of passion for their own work), and he's lived in Malaysia long enough to have had plenty to be upset about before in regards to Anwar Ibrahim.

I don't yet know enough about the First Officer to form a proper opinion, but what I've learned thus far has not really raised any red flags to me.

So we're left with the inhabitants of the cabin, including two large parties (Freescale employees and a group of prominent Chinese artists), ten cabin crew (which may not include an MAS engineer assigned to Beijing), a couple of people travelling on false passports and an Uighar gentleman with some previous interest in flight simulation.

My own speculation is as follows, and it is by no means compelling or perfect:

I mentioned previously that part of the E&E bay was accessible from inside the cabin. It requires a proprietary screwdriver design to access, but once accessed, it would be possible to pull all the circuit breakers you could possibly need to shut down the transponder and other various systems (including the VHF component of ACARS) fairly quietly. It'd also be a good opportunity to pull the necessary circuit breaker for the pressurization system. In doing so, you'd have roughly 12 minutes before hypoxia set in, but after that happened (assuming you had bottled air), the aircraft would be all yours.

12 minutes isn't enough time from the shutoff of the transponder to the last ATC voice contact, although not all the breakers need to be pulled at once. I would have expected the cabin pressurization breaker to be the first thing to pull, though. In any case, it's entirely possible for the crew to not know about it, and someone with engineering credentials and an MAS uniform would get access in literally seconds without anyone batting an eyelid.

This all assumes that the passengers aren't the objective, and given the lack of a list of demands, I'd be inclined to believe that this is the case.

Of course, it could be a suicide attempt by a Captain or First Officer, it could be a takeover gone wrong (which would require E&E bay access to kill the transponder and ACARS VHF system 20 minutes prior to the takeover), and it could still be a mechanical disaster (except that saying 'goodnight' to the ATC after the transponder and ACARS VHF system are offline is a worry).