The flight crew of the missing Malaysian jet made its last radio contact with air traffic controllers after the aircraft's automatic signaling system was disabled, a Malaysian transport official said Sunday.
"The ACARS (Aircraft Communications Addressing and Reporting System) communications system was disabled before last radio contact between plane and air traffic," said Malaysian Airlines Chief Executive Ahmad Jauhari Yahya.
Malaysia’s Prime Minister Najib Razak said early Saturday that the aircraft’s ACAR system was disabled first, and then the aircraft’s transponder was shut off before the flight veered off course.
The ACARS is located on a lower-level of the plane, while the transponder is housed in the cockpit, Tom Casey, a retired pilot who used to fly the giant Boeing 777 told NBC News on Saturday. In order to disconnect the ACAR system, a person would have to pull a series of circuit breakers, but also know where to find them, Casey noted.
Razak also said Saturday that the plane was diverted because of a "deliberate action by someone on the plane.” He said the investigation would focus on the passengers and crew.