A Malaysia Airlines plane sent signals to a satellite for four hours after the aircraft went missing, an indication that it was still flying, says a US official briefed on the search for the plane.
The Boeing 777-200 wasn't transmitting data to the satellite, but was instead sending out a signal to establish contact, said the official, who spoke on condition of anonymity because he wasn't authorised to discuss the situation by name.
Boeing offers a satellite service that can receive a stream of data during flight on how the aircraft is functioning.
Malaysia Airlines didn't subscribe to that service, but the plane still had the capability of connecting with the satellite and was automatically sending pings, the official said.
The continuing pings led searchers to believe the plane could have flown more than 1600 km beyond its last confirmed sighting on radar, the official said.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
The plane had enough fuel to fly about four more hours, he said.
Messages involving a different data service also were received from the airliner for a short time after the plane's transponder - a device used to identify the plane to radar - went silent, the official said.
