One theory that’s been kicking around the Internet is that the crew and passengers fell victim to a Payne Stewart situation. The cabin depressurized, everyone blacked out, and the plane continued on blindly via autopilot until it ran out of fuel and crashed. It’s a horrible accident, not foul play.

So much for that theory.

Analysis of the Malaysia data suggests the plane, with 239 people on board, diverted from its intended northeast route from Kuala Lumpur to Beijing and flew west instead, using airline flight corridors normally employed for routes to the Middle East and Europe, said sources familiar with investigations into the Boeing 777’s disappearance.

Two sources said an unidentified aircraft that investigators believe was Flight MH370 was following a route between navigational waypoints when it was last plotted on military radar off the country’s northwest coast.

This indicates that it was either being flown by the pilots or someone with knowledge of those waypoints, the sources said…

“What we can say is we are looking at sabotage, with hijack still on the cards,” said that source, a senior Malaysian police official.

If the plane was on autopilot, presumably it would have continued on in a roughly northeastern direction towards its destination in Beijing. Instead, it made a hard left — and then, somehow, it stayed on the aerial “road” (i.e. between the waypoints) instead of veering off randomly. Imagine blacking out behind the wheel on cruise control and the car not only turning but then staying in its lane on the highway for hundreds of miles. Assuming the sources are right, someone had to have been steering.

More evidence of deliberate action:

Two U.S. officials tell ABC News the U.S. believes that the shutdown of two communication systems happened separately on Malaysia Airlines Flight 370. One source said this indicates the plane did not come out of the sky because of a catastrophic failure.

The data reporting system, they believe, was shut down at 1:07 a.m. The transponder — which transmits location and altitude — shut down at 1:21 a.m…

That means the U.S. team “is convinced that there was manual intervention,” a source said, which means it was likely not an accident or catastrophic malfunction that took the plane out of the sky.

Obvious question: If this was some sort of suicide mission, either by one of the pilots or a hijacker, why bother shutting down the data systems? Why, for that matter, bother flying west at all? Just take the plane down and be done with it.

A new theory based on the “pings” the plane sent while flying west towards the Indian Ocean was that it was headed towards the Andaman Islands. In that case, though, where would it land? The editor of the islands’ newspaper says there’s no way a 777 could show up at the local airport without attracting notice. And if this is a hijacking, how come there’s been no information after a week about possible suspects onboard? The two Iranians with stolen passports were mentioned early but counterterror officials dismissed them quickly. Usually after a hijacking, authorities are able to deduce fairly quickly who the likely suspects are from the passenger manifest and interviews with friends and family. Not this time. Was it a lone wolf who left few red flags or do they have a lead and are keeping quiet about it for now until they have better evidence?

One more mystery. If the plane was in the Indian Ocean headed west, why was there a “seismic event” in the ocean south of Vietnam, not far from the jet’s last known location, on the night it disappeared?

The signal detected by two stations in Malaysia appeared to indicate that a small tremor occurred on the floor of the sea at 2:55 a.m. about 95 miles south of Vietnam, the scientists said in a statement posted on the website of the University of Science and Technology of China.

“It was a non-seismic zone, therefore judging from the time and location of the event, it might be related to the missing MH370 flight,” said the statement. “If it was indeed an airplane crashing into the sea, the seismic wave strength indicated that the crash process was catastrophic.”

The area where the tremor was detected about 70 miles from where the Boeing 777 was last heard from, and 85 minutes after the jet carrying 239 people lost contact, according to South China Morning Post newspaper.

Must be a coincidence. Seems fairly solid at this point that satellites were being pinged by the plane hundreds of miles west of that location. The timeline doesn’t make sense either; surely the plane would have covered more than 70 miles in 85 minutes after it went quiet.

If this really is terrorism, though, why has there been no chatter? Gen. Tom McInerney casually wondered this morning on Fox News whether maybe jihadis targeted the plane because they need a delivery mechanism for, er, a nuclear weapon. I’m thinking there must be better ways to quietly procure a plane, though, than by kicking off a global manhunt for a missing jumbo jet.

Any theories on all this, “Ancient Aliens” guy?

Update: Here’s a charming theory forwarded from a friend. Sleep tight, America.

My wife has been saying for a week that terrorists landed it in an obscure airport and are loading it up with uranium to detonate over a large city.

How much uranium could they possibly have to require a 777 to disperse it?

Update: My friend replies that they might not need a jumbo jet for its size but rather for its range. If you’re looking to hit a target in Israel or Europe and you’re starting in Malaysia, you need a plane that can fly long distances. In that case, though, why have they waited a week to get the jet back up in the air? If you’re going to do something like this, where you land a jet, load it up with something, and then aim it at a target, you need to work quickly before western intel figures out what’s happening. The alleged terrorists here have waited a week. Doesn’t add up.