And by “wrong direction,” I mean the opposite direction. It was headed north to Beijing, then suddenly the transponder was switched off and it swung all the way around to the left until it was flying southwest, where it continued on for 350 miles. It didn’t blow up in mid-air.

Which, it seems, means one of two things. Could be that the pilot, for unknown reasons, decided he had to turn around and try to make it back to the airport at Kuala Lumpur, then simply flew off course. In that case, though, why would he turn off the transponder — and, presumably, the other navigation equipment? If the equipment malfunctioned, how did the plane manage to fly hundreds of miles after the malfunction?

Alternate theory: It was hijacked. Police are skeptical about terrorism here, though. They’ve all but ruled out involvement by the two Iranians who were carrying stolen passports. Evidently that’s not uncommon on flights in southeast Asia.

Could the pilots have done it deliberately? Why?

“It changed course after Kota Bharu and took a lower altitude. It made it into the Malacca Strait,” the senior military officer, who has been briefed on investigations, told Reuters…

Malaysia’s Berita Harian newspaper quoted air force chief Rodzali Daud as saying the plane was last detected at 2.40 a.m. by military radar near the island of Pulau Perak at the northern end of the Strait of Malacca. It was flying about 1,000 meters lower than its previous altitude, he was quoted as saying…

The effect of turning off the transponder is to make the aircraft inert to secondary radar, so civil controllers cannot identify it. Secondary radar interrogates the transponder and gets information about the plane’s identity, speed and height.

It would however still be visible to primary radar, which is used by militaries.

Lots of mini-mysteries here. Why did it take the Malaysian military four days to let everyone know that the jet didn’t vanish south of Vietnam, as the world had been led to believe? Why were they searching in that area at all? More importantly, is it even true that the plane made it all the way back to the Strait of Malacca? According to the NYT, no:

Adding to the confusion, Tengku Sariffuddin Tengku Ahmad, spokesman for the prime minister’s office, said in a telephone interview that he had checked with senior military officials, who told him there was no evidence that the plane had recrossed the Malaysian peninsula, only that it may have attempted to turn back.

“As far as they know, except for the air turn-back, there is no new development,” Mr. Tengku Sariffuddin, adding that the reported remarks by the air force chief were “not true.”

Malaysia Airlines, meanwhile, offered a third, conflicting account. In a statement, the airline said authorities were “looking at a possibility” that the plane was headed to Subang, an airport outside Kuala Lumpur that handles mainly domestic flights.

Follow the last link and scroll down to the Times’s map to see how far apart the old search area and the new search area are. Yet another mini-mystery: Is it significant that some of the passengers’ cell phones were still online as of Sunday afternoon? NBC says no, not really. WaPo seems more intrigued:

One of the most eerie rumors came after a few relatives said they were able to call the cellphones of their loved ones or find them on a Chinese instant messenger service called QQ that indicated that their phones were still somehow online.

A migrant worker in the room said that several other workers from his company were on the plane, including his brother-in-law. Among them, the QQ accounts of three still showed that they were online, he said Sunday afternoon.

Adding to the mystery, other relatives in the room said that when they dialed some passengers’ numbers, they seemed to get ringing tones on the other side even though the calls were not picked up.

Were there no working onboard-phones on a modern jet like the Boeing 777? If it was a hijacking and the passengers knew it, someone would have called someone, no? Either they didn’t know or the plane crashed somewhere before they figured it out.

Here’s your thread for irresponsible speculation. If you want to help look for evidence of the jet in the Strait of Malacca, ABC says this site is the place to be.