US investigators suspect that Malaysia Airlines Flight 370 stayed in the air for about four hours past the time it reached its last confirmed location, the Wall Street Journal reported, citing two people familiar with the details.
The report comes as authorities remain uncertain about which ocean to search for the jetliner that went missing on Saturday after taking off from Kuala Lumpur. The latest disclosure led US investigators to explore the possibility that someone deliberately turned off the transponder and diverted the plane to another location, the newspaper reported.
It raises the possibility that the plane, and the 239 people on board, could have flown on for additional distance of about 2,200 miles (3,500 km), potentially reaching the border of Pakistan or as far as destinations in the Indian Ocean or Arabian Sea, the paper said.
The last definitive sighting of the aircraft on civilian radar screens came shortly before 1:30 a.m. on Saturday, less than an hour after taking off from Kuala Lumpur, as it flew northeast across the mouth of the Gulf of Thailand bound for Beijing.
Aviation investigators and national security officials believe the plane flew for a total of five hours based on data automatically downloaded and sent to the ground from the Boeing Co 777's engines as part of a standard monitoring program, the Journal said.
One person told the paper that, as part of a maintenance agreement, the Malaysia Airlines plane was able to transmit engine data live to Rolls-Royce for analysis. The system sends data from the Boeing 777's two Trent 800 engines, giving details such as altitude and speed of the jet.
US counterterrorism officials are pursuing the possibility that a pilot or someone else on board the plane may have diverted it toward an undisclosed location after intentionally turning off the jetliner's transponders to avoid radar detection, the newspaper reported, citing one person tracking the probe.
A senior Malaysia Airlines executive said on Wednesday that the airline has "no reason to believe" that any actions by the crew caused the disappearance of a jetliner.
At one briefing, US officials were told investigators are actively pursuing the notion that the plane was diverted "with the intention of using it later for another purpose," the Journal said.
On Tuesday, the international police agency Interpol's head said they do not believe the disappearance of the jet was the result of a terrorist attack.