• Heat sensors scouring uninhabited island for missing jet
• Angry passengers cling to hope

Piracy and pilot suicide are among the scenarios under study as investigators grow increasingly certain the missing Malaysia Airlines jet changed course and headed west after its last radio contact with air traffic controllers.

The latest evidence suggests the plane didn’t experience a catastrophic incident over the South China Sea as was initially suspected.

Some experts theorise that one of the pilots, or someone else with flying experience, hijacked the plane or committed suicide by plunging the jet into the sea.

Adding to the speculation that someone was flying the jet, The New York Times on Friday quoted sources familiar with the investigation as saying that the plane experienced significant changes in altitude after it lost contact with ground control, and altered its course more than once.

A US official told The Associated Press earlier that investigators are examining the possibility of “human intervention” in the plane’s disappearance, adding it may have been “an act of piracy.”

The official, who spoke on condition of anonymity, said it was possible the plane may have landed somewhere.

The official later said there was no solid information on who might have been involved.

Members of the public, Malaysia Airlines staff and authorities pray for a breakthrough. Photo: Getty

While other theories are still being examined, the official said key evidence suggesting human intervention is that contact with the Boeing 777’s transponder stopped about a dozen minutes before a messaging system on the jet quit.

Such a gap would be unlikely in the case of an in-flight catastrophe.

A Malaysian official, who declined to be identified because he is not authorised to brief the media, said only a skilled aviator could navigate the plane the way it was flown after its last confirmed location over the South China Sea.

The official said it had been established with a “more than 50 per cent” degree of certainty that military radar had picked up the missing plane after it dropped off civilian radar.

Fate unknown

Malaysia’s acting transport minister, Hishammuddin Hussein, said the country had yet to determine what happened to the plane after it ceased communicating with ground control about 40 minutes into the flight to Beijing on March 8 with 239 people aboard, including six Australians and two New Zealanders.

He said investigators were still trying to establish that military radar records of a blip moving west across the Malay Peninsula into the Strait of Malacca showed Flight MH370.

“I will be the most happiest person if we can actually confirm that it is the MH370, then we can move all (search) assets from the South China Sea to the Strait of Malacca,” he told reporters.

Until then, he said, the international search effort would continue expanding east and west from the plane’s last confirmed location.

Though some investigators are now convinced that “human intervention” caused the disappearance, US officials told the White House at a briefing on Friday that they have “run all the traps” and come up with no good information on who might been involved, according to an official familiar with the meeting.

Unidentified blip

Malaysian military radar continued to pick up the plane as a whole “paintskin” – a radar blip that has no unique identifier – until it travelled beyond the reach of radar, which is about 320 kilometres offshore, the official said.

The New York Times, quoting American officials and others familiar with the investigation, said radar signals recorded by the Malaysian military appear to show the airliner climbing to about 13,700 metres, higher than a Boeing 777’s approved limit, soon after it disappeared from civilian radar, and making a sharp turn to the west.

The radar track then shows the plane descending unevenly to an altitude of 7000 metres, below normal cruising levels, before rising again and flying northwest over the Strait of Malacca toward the Indian Ocean, the Times reported.

Scores of aircraft and ships from 12 countries are involved in the search, which reaches into the eastern stretches of the South China Sea and on the western side of the Malay Peninsula, northwest into the Andaman Sea and the Indian Ocean.

Heat sensors

India said it was using heat sensors on flights over hundreds of Andaman Sea islands and would expand the search for the missing jet farther west into the Bay of Bengal, more than 1600 kilometres to the west of the plane’s last known position.

At this point, there is no evidence of any wrongdoing on the part of the two pilots, though Malaysian police have said they are looking at their psychological background, their family life and connections.

Zaharie Ahmad Shah, 53, and Fariq Abdul Hamid, 27, have both been described as respectable, community-minded men.

Mike Glynn, a committee member of the Australian and International Pilots Association, said he considers pilot suicide to be the most likely explanation for the disappearance, as was suspected in a SilkAir crash during a flight from Singapore to Jakarta in 1997 and an EgyptAir flight in 1999.

“A pilot rather than a hijacker is more likely to be able to switch off the communications equipment,” Glynn said.

AP