KUALA LUMPUR, (USA TODAY): Malaysia’s Prime Minister Najib Razak said a news conference in Kuala Lumpur on Saturday that the transponder on the missing Malaysia Airlines jetliner was disabled by “deliberate action” just before the aircraft reached the east coast of Vietnam.

According to new satellite data analyzed by the FAA, NTSB, Malaysian Royal Air Force and other authorities, the last confirmed communication from the plane’s transponder was 8:11 a.m. Malaysia time.

Based on the data, the search for flight is entering a “new phase,” focusing on two possible corridors — a northern corridor from the border of Kazakstan and Turkmenistan through to northern Thailand, and a southern corridor from Indonesia to the southern Indian Ocean.

Razak announced that search operations were ending in the South China Sea and investigators are refocusing their attention onto the pilots and passengers on board Flight MH370.

Indian ships and planes expanded their search Friday to areas west of the Andaman and Nicobar islands chain, hundreds of miles from the intended course of Flight MH370, said V.S.R. Murty, an Indian Coast Guard inspector-general.

Several media outlets reported that U.S. officials said the flight sent signals to a satellite for four hours after the aircraft vanished early Saturday, raising the possibility the jet with its 239 people aboard could have flown far from the search areas.

ABC News reported that two U.S. officials said two of the jet’s communication systems shut down separately shortly after the craft last communicated its position.

The data reporting system, the officials said, was shut down at 1:07 a.m. as the jet was on course an hour after takeoff from Kuala Lumpur to Beijing. The transponder, which transmits location and altitude, shut down at 1:21 a.m.

The officials could not say whether the mechanisms were shut down deliberately by someone in the cockpit or during a possible electrical failure in which various systems shut down one after the other.

Pointing to the communication systems’ separate shutdowns, a U.S. official told the Associated Press that investigators are examining the possibility of “human intervention” in the jet’s disappearance, adding it may have been “an act of piracy.” The official, who wasn’t authorized to talk to the media and spoke on condition of anonymity, said it was possible the jet may have landed somewhere.

While searchers moved ahead with the possibility that the jet flew well to the west of its intended flight path after communication ended, seismologists at a Chinese university reported Friday they had detected a slight “seismic event” on the seafloor between Vietnam and Malaysia at the spot where the jet was around the time it vanished.

The report, first carried by the South China Morning Post, noted the area is not an earthquake zone.

“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,” the statement said.

The U.S. Geological Survey (USGS) located a magnitude-2.7 earthquake off the west coast of Sumatra at the time of the “seismic event” noted by the Chinese, said Harley Benz of the USGS National Earthquake Information Center in Denver.

Benz said tremors of that size are a daily occurrence in the region, refuting the Morning Post‘s claim. Other earthquake expertssaid such seismic activity is unlikely to be caused by a plane crash.

“It’s very unlikely that the aircraft would have hit the undersea floor strong enough to cause a seismic event that we could detect,” said Paul Caruso, a geophysicist with USGS.

“The bump from the plane hitting bottom of the ocean would not be noticeable,” said earthquake expert John Vidale of the University of Washington.

MORE: 6 theories on what happened to Malaysia Flight 370

Malaysia’s acting Transport minister, Hishammuddin Hussein, refused to comment Friday on the possibility that the jet had flown for hours off course. He said the investigation team will not address or release information about any of those claims or others until the suggestions have been verified and corroborated.

“I hope within a couple of days to have something conclusive,” he told the news conference in Kuala Lumpur.

Much of the early search has focused east of Malaysia in the South China Sea, where the aircraft last communicated with air-traffic base stations about an hour after departing for Beijing.

Two days ago, six Indian navy and coast guard ships, plus reconnaissance planes, began searching eastern parts of the Andaman sea. Friday, they headed west of the Andaman and Nicobar islands near the Bay of Bengal.

There are more than 500 islands in that chain, many of which are richly forested and uninhabited.

Thursday, The Wall Street Journal quoted U.S. investigators as saying they suspected the jet stayed in the air for about four hours after its last confirmed contact, citing data automatically transmitted by the jet’s satellite communication link.

http://www.usatoday.com/story/news/world/2014/03/15/malaysia-airlines-flight-missing/6451477/