[Update: CNN's Jim Clancy, is reporting that a "senior Air Force source" said that, shortly after they lost contact, the aircraft changed altitude "erratically" before settling back at Flight Level 350.
Also being reported in the media that the communications systems within the aircraft were shut down from the cockpit at two different times, about 14 minutes apart. "The United States believes that the shutdown of two communications systems on missing Malaysia Airlines flight MH370 occurred separately, indicating that it may have been a deliberate act, ABC News reported today, although other American officials said the Boeing 777-200ER had sent data for another four hours after vanishing from radar screens. According to the report, two US officials said that they believe the data reporting system was shut down at 1.07 am, while the transponder was shut down at 1.21 am on Saturday, when the flight carrying 239 people vanished from radar screens. "This indicates that it may well have been a deliberate act," ABC news aviation consultant John Nance reportedly said."]
Information from the Wall Street Journal:
“The 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.
WSJ’s Andy Pasztor has been reporting on Flight MH370 since it disappeared. Here he explains how a plane can still transmit “pings” that allow investigators to track it even after its main tracking systems — or transponders — are shut off.
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.” WSJ
So the United States government, at least, knows where the plane’s last traceable location really is.
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.