Signaling system ‘was disabled’ on missing Malaysia Airlines

A signaling system was disabled on the missing Malaysia Airlines jet before a pilot spoke to air traffic control without mentioning any trouble, a senior Malaysian official has said, reinforcing theories that one or both of the pilots may have been involved in diverting the plane and adding urgency to the investigation of their pasts and possible motivations.

Prime Minister Najib Razack acknowledged that military radar and satellite data raised the possibility that the plane could have ended up somewhere in Indonesia, the southern Indian Ocean or along a vast arc of territory from northern Laos across western China to Central Asia.

Malaysian officials said they were scrambling to coordinate a 25-nation effort to find the plane.

On Sunday, Malaysia’s defense minister added a critical detail about investigators’ understanding of what had transpired in the cockpit in the 40 minutes of flight time before ground controllers lost contact with the jet. The determination that the last verbal message to the control tower — “All right, good night” — came after a crucial signaling system had stopped transmitting, perhaps after being shut off, was likely to refocus scrutiny on the plane’s veteran pilot, Capt. Zaharie Ahmad Shah, 53, and his young first officer, Fariq Abdul Hamid, 27.

Commercial passenger planes use radio or satellite signals to send data through Acars, the Aircraft Communications Addressing and Reporting System. The system can monitor engines and other equipment for problems that may need attention when a plane lands.

Although officials have already said that Acars was disabled on the missing plane, it had been unclear whether the system stopped functioning before or after the last, brief words were radioed to the control tower, in which the pilot did not indicate that anything was wrong with the signaling system or the plane as a whole.

The plane took off at 12:41 a.m. on March 8 carrying 239 people headed for Beijing and reached a cruising altitude of 35,000 feet at 1:01 a.m. Six minutes later, at 1:07 a.m., the Malaysian authorities say, the plane sent its last Acars message, which reported nothing amiss.

The sequence of events does not rule out the possibility of someone taking control of the cockpit and forcing the pilot to disable the system, say good night to air traffic control and turn off the transponder. But if that is what happened, it means the hijacker would have had to seize the cockpit in the first 26 minutes of the flight.