On March 8, 2014, Malaysia Airlines Flight MH370, a Boeing 777 passenger jet, took off from Kuala Lumpur bound for Beijing with 227 passengers and 12 crew aboard. At 1:19 a.m. local time[1]. the aircraft left Malaysian airspace and was handed off to Vietnam air traffic control.  The pilot, 53-year old Captain Zaharie Ahmad Shah, responded, “Good night. Malaysian 370.”  That was the last contact with the flight.  One minute later the aircraft’s transponder signal disappeared from controller’s radar screens, and one of the aviation’s greatest mysteries began unfolding.

Two years later, what can be said about the fate of MH370? Here are the known facts.

Military radar showed the aircraft make a sharp left turn to a southwesterly heading, almost opposite to its route to Beijing, at the time the transponder signal vanished. It then flew southwest across the Malay peninsula for half an hour. At 1:52 a.m. it passed over the west coast of the peninsula near Penang, turned northwest and continued on that course for another half hour. Radar contact was lost at 2:22 a.m.

The aircraft was equipped with a satellite communications system known as ACARS (Aircraft Communications Addressing and Reporting System). At 2:25 a.m. the on-board system sent a log-on request called a “handshake” to the satellite, which relayed it to a ground station operated by the satellite communications company Inmarsat.  At 2:40 a.m. a satellite phone call was sent to the aircraft, which went unanswered. However, ground stations continued to make regular hourly handshakes with the aircraft’s on board system.

At 7:13 a.m. another telephone call to MH370 went unanswered. The aircraft initiated a final handshake with the satellite at 8:19 a.m. Then, at 9:15 a.m., MH370 failed to respond to a handshake from the ground. No further satellite contacts followed.

After MH370 disappeared the Australian Transport Safety Bureau (ATSB) assumed responsibility for the search. In June, 2014 the ATSB issued a report based on forensic analysis of the satellite communications which concluded that shortly after the loss of radar contact at 2:22 a.m. MH370 turned left to a southwesterly heading, and continued in that direction for six hours until fuel exhaustion.  On that basis, the ATSB established a search area in the South Indian Ocean, approximately 1,500 miles west of Australia.

On July 29, 2015 a Boeing 777 control surface washed ashore on Reunion Island, approximately 2,500 miles west of the search area. Investigators from France, Malaysia and the United States determined that it came from MH370.

In December, 2015 the ATSB released an updated report including new information. Electrical power to MH 370’s satellite communication system was interrupted sometime between 1:20 a.m. (the last transponder signal) and 2:03 a.m., when a ground station made an unsuccessful handshake request. At 2:25 a.m., MH370’s satellite communication system initiated a successful handshake, indicating that electrical power had been restored sometime during the preceding 22 minutes. The ATSB stated that such an interruption could result from turning the generator switches off and then on from the cockpit, or from pulling and re-setting circuit breakers in the electronic equipment bay. The ATSB further concluded that the right engine ran out of fuel at approximately 8:05 a.m., followed by the left engine at approximately 8:17 a.m., when MH370’s auxiliary power unit (APU) started automatically. The last handshake at 8:19 a.m. occurred on APU power with both engines stopped, followed by final fuel exhaustion and APU shutdown at 8:20 a.m.

What conclusions can be drawn from these facts?

Any accidental scenario must account for loss of MH370’s transponder signal and its radical change in direction of flight immediately following the last radio communication, and two subsequent large direction changes within the next half hour. Those changes are inconsistent with crew incapacitation.  A fire or other catastrophic event is inconsistent with the fact that the engines and systems continued to function for more than six hours thereafter. The electrical power interruption while MH370 was flying over Malaysia could have been triggered from the flight deck or the electronic equipment bay.

Unless and until the wreckage is located on the ocean floor and the flight data recorder and cockpit voice recorder data recovered, the most plausible scenario is deliberate human action, most likely by one of the cockpit crew, who were familiar with the Boeing 777’s systems. Such events are exceedingly rare, but not unknown, as occurred with EgyptAir Flight 990 in October, 1999, and Germanwings Flight 9525 in March 2015.