According to The New York Times, American officials and others familiar with the investigation say that the Malaysia Airlines jetliner experienced significant changes in altitude after ground control lost contact with the plane, and also altered its course more than once, reporting:
Radar signals recorded by the Malaysian military appear to show the missing airliner climbing to 45,000 feet, above the approved altitude limit for a Boeing 777-200, soon after it disappeared from civilian radar and made a sharp turn to the west, according to a preliminary assessment by a person familiar with the data.
The radar track, which the Malaysian government has not released but says it has provided to the United States and China, then shows the plane descending unevenly to 23,000 feet, below normal cruising levels, as it approached the densely populated island of Penang, one of the country’s largest. There, the plane turned from a southwest-bound course, climbed to a higher altitude and flew northwest over the Strait of Malacca toward the Indian Ocean.
Reuters also reported earlier today that new military radar information suggests the missing Malaysia Airlines jetliner was deliberately flown off course, "heightening suspicions of foul play."
Sources told the news service that the plane was diverted westward along flight corridors typically reserved for flights to the Middle East and Europe.
"What we can say is we are looking at sabotage, with hijack still on the cards," said that source, a senior Malaysian police official.
All three sources declined to be identified because they were not authorized to speak to the media and due to the sensitivity of the investigation.
ABC News further reports that two communications systems on fated Malaysia Airlines Flight MH370 were turned off separately, and quotes an expert who believes this may indicate those systems were deliberately deactivated.
The plane’s data reporting system was reportedly shut down at 1:07 a.m. local time, with a second transponder transmitting location and altitude was taken off-air at 1:21 a.m.
US investigators told ABC News that the two modes of communication were "systematically shut down."
That means the US team "is convinced that there was manual intervention," a source told ABC News, which means it was likely not an accident or catastrophic malfunction that took the plane out of the sky.
Authorities have now extended their search to include the Indian Ocean, after “technical indicators” suggested that the plane continued to fly - potentially for hours - after its radar signal was lost.