Among the possible scenarios investigators said they are now considering is whether the jet may have landed at any point during the five-hour period under scrutiny, or whether it ultimately crashed.
The people said aviation investigators are exploring the possibility that someone on the plane may have intentionally disabled two other automated communication systems in an attempt to avoid detection. One system is the transponders, which transmit to ground radar stations information on the plane’s identity, location and altitude, and another system that collects and transmits data about several of the plane’s key systems.
The widebody jet was scheduled to fly overnight to Beijing from Kuala Lumpur in the predawn hours of March 8. Its transponders last communicated with Malaysian civilian radar about an hour after takeoff.
After the plane dropped off civilian radar screens, these people said, the satellite link operated in a kind of standby mode for several hours and sought to establish contact with a satellite or satellites. These transmissions didn’t include data about any of the plane’s critical systems, they said, but the periodic contacts indicate to investigators that the plane was still intact and believed to be flying at least a significant portion of that time. The people said the transmissions included detailed information about the plane’s location, speed and bearing.
The transmissions, one person said, were comparable to the plane “saying I’m here, I’m ready to send data.”
Unknown so far to investigators is what happened to the plane following the final satellite ping, these people said. Questions remain about the plane’s status, including what was happening in the cockpit.
But the huge uncertainty about where the plane was headed, and why it apparently continued flying so long without working transponders and other communication links, has raised theories among investigators that the aircraft may have been commandeered for reasons that remain unclear to U.S. authorities.