U.S. law enforcement officials say investigators searching a home flight simulator and e-mails of the pilots of the missing Malaysian airliner have failed to find evidence that either pilot purposely steered the flight away from its destination.
The two U.S. law enforcement officials spoke Tuesday after being briefed by Malaysian authorities who are leading a 26-nation search for Malaysia Airlines Flight 370.
The airliner, bound for Beijing with 239 people aboard, vanished over Southeast Asia March 8, triggering the largest missing airplane search in aviation history.
One of the U.S. officials said authorities were trying to learn whether pilot Zaharie Ahmad Shah might have been training on the simulator on how to disable transponders and other in-flight devices ahead of takeoff from Kuala Lumpur. Investigators were also seeking to learn whether he had practiced flight patterns taking the plane away from its destination.
The official, quoted by the Los Angeles Times, also noted that the Malaysian co-pilot was making preparations for his wedding in his homeland.
Earlier Tuesday, Malaysian authorities said the search for the Boeing 777 airliner had been expanded to cover more than seven million square kilometers, an area roughly the size of Australia. The territory extends from Central Asia in the north to the vast waters of the Indian Ocean to the south.
Thailand's military released new radar information Tuesday that could support earlier reports that the Malaysia Airlines jet made a sharp turn to the west toward the Strait of Malacca after its last contact was recorded north of Malaysia.
The Thai government said its radar detected a plane that may have been the missing Flight 370, but initially paid little attention to the jet because it was not a threat to its territorial security.
Malaysian Defense Minister Hishammuddin Hussein called for more international cooperation in helping narrow the search. Authorities believe the jet was deliberately diverted and flown either toward Central Asia or over the Indian Ocean.
Authorities have so far refused to rule out any possibility, including terrorism, hijacking, a mechanical malfunction or pilot suicide.
Meanwhile, Huang Huikang, China's ambassador to Malaysia, said extensive background checks completed on the 154 Chinese passengers showed none with links to terrorism or hijacking.
"China has conducted a thorough investigation on the background (of Chinese passengers aboard). So far, (China) has not found any actions that jeopardized Malaysia Airlines MH 370 flight. So we can rule out the possibilities of Chinese passengers suspected of being involved in any kind of terror or jeopardizing activities."
The ambassador also said China has begun looking for the aircraft "in the territory along the northern corridor" of the search area.
The New York Times first reported Tuesday that the plane's intended route appears to have been altered by a computer system mostly likely programmed by someone in the cockpit with knowledge of advanced aircraft systems.
U.S. officials say the development reinforces the theory that foul play is involved in the disappearance.