Why the search for missing plane has moved to Indian Ocean area

WSJ:

Malaysia Airlines 3786.KU +2.13% ' missing jet transmitted its location repeatedly to satellites over the course of five hours after it disappeared from radar, people briefed on the matter said, as searchers zeroed in on new target areas hundreds of miles west of the plane's original course.

The satellites also received speed and altitude information about the plane from its intermittent "pings," the people said. The final ping was sent from over water, at what one of these people called a normal cruising altitude. They added that it was unclear why the pings stopped. One of the people, an industry official, said it was possible that the system sending them had been disabled by someone on board.

The people, who included a military official, the industry official and others, declined to say what specific path the transmissions revealed. But the U.S. planned to move surveillance planes into an area of the Indian Ocean 1,000 miles or more west of the Malay peninsula where the plane took off, said Cmdr. William Marks, the spokesman for the U.S. Seventh Fleet.

He said the destroyer USS Kidd would move through the Strait of Malacca, on Malaysia's west coast, and stay at its northwest entrance. Malaysia, which is overseeing the search effort, directed Indian forces to a specific set of coordinates in the Andaman Sea, northwest of the Malay peninsula, an Indian official said Thursday. "There was no specified rationale behind looking in those areas, but a detailed list was provided late Wednesday evening," the Indian official said.

The automatic pings, or attempts to link up with satellites operated by Inmarsat PLC, occurred a number of times after Flight 370's last verified position, the people briefed on the situation said, indicating that at least through those five hours, the Boeing Co. BA -2.04% 777 carrying 239 people remained intact and hadn't been destroyed in a crash, act of sabotage or explosion.

Malaysia Airlines said it hadn't received any such data. According to Boeing, the plane's manufacturer, the airline didn't purchase a package through Boeing to monitor its airplanes' data through the satellite system.

If the plane remained airborne for the entire five hours, it could have flown more than 2,200 nautical miles from its last confirmed position over the Gulf of Thailand, the people said.
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There is more.

Other on board communication systems appear to have been disabled.   With this new data investigators are probably also looking at the passenger list to see if there was anyone on board with pilot training and knowledge of the systems on board the 777.  The inconsistent messaging from the Malaysians  may stem from a reluctance to let a potential terrorist know what they know about the whereabouts of the plane, or it could be just an incoherent response to events.