KUALA LUMPUR The Malaysian passenger jet that disappeared on Saturday did not make automatic contact with a flight data-monitoring system after vanishing from radar screens, two people familiar with the matter said.
The Boeing 777-200ER is equipped with a maintenance computer capable of talking to the ground automatically through short messages known as ACARS.
These help technicians prepare any necessary repairs and shorten turnaround times at the destination.
Automated ACARS error messages from an Airbus A330 that vanished in the Atlantic in 2009 focused attention initially on inconsistent speed readings as a possible cause of that crash.
Although black-box evidence later showed that pilot error was mainly to blame for the loss of the Air France jet, the burst of error messages was a sign that basic electrical systems continued to work during the aircraft's four-minute descent.
In the case of the Malaysia Airlines jet, however, investigators have no such evidence to help them discover what happened to the passenger plane, the people said.
"There were no signals from ACARS from the time the aircraft disappeared," a source involved in the investigations said.
Flight MH370 disappeared early on Saturday about an hour into its flight from Kuala Lumpur to Beijing after climbing to a cruising altitude of 35,000 feet.
Malaysia on Monday called the disappearance an unprecedented mystery as a massive air and sea search now in its third day failed to find any trace of the plane or 239 people on board.
In addition to standard ACARS messages, airlines can install a system sold by Boeing called Airplane Health Management which provides real-time troubleshooting and allows Boeing to monitor the flight as well as the airline, according to its brochure.
This optional system was not installed on the missing Malaysia Airlines jet, people familiar with the matter said.
U.S. planemaker Boeing declined to comment.
(Reporting by Siva Govindasamy in Kuala Lumpur, Tim Hepher in London, Alwyn Scott in New York, editing by Louise Heavens)