In the first few minutes of the long, mysterious vanishing of the big, Beijing-bound Malaysian jet, abnormal and deliberate changes to the course of the Boeing 777 were keyed into the cockpit's flight computer and vital communications systems were switched off and silenced.
Very little is known about the next seven-plus hours except the jet was still flying – possibly with everyone on board dead or incapacitated – before it ran out of fuel and plunged, likely into the southern Indian Ocean, one of the planet's remotest places.
Few scenarios match the two distinct and seemingly incompatible phases of activity in the disappearance of MH370.
The change of course, the routine last voice communication with air traffic control, the switching off of the aircraft's transponder – which broadcasts speed, direction, altitude and a flight identifier – and the disabling of the automatic data reporting system, all point to deliberate acts by a pilot, perhaps under coercion, or someone with detailed and sophisticated knowledge of the systems on the Boeing 777.
Going silent – trying to hide the aircraft from routine monitoring and reporting – is consistent with a hijacking or even pilot suicide. But hijackers want to go somewhere. Terrorists who plan to turn fuel-laden jetliners into human-guided missiles need targets within range. Suicidal pilots usually dive for the sea as soon as they have control, not wait for hours.
That the missing Boeing 777 kept flying for seven more hours is known only because the plane's satellite communications system was – every 30 minutes or so – "handshaking" with a satellite high above the Indian Ocean, much as a cell phone checks in with a nearby tower even if it isn't in use and its data function has been turned off.
The last phase of MH370's long flight to nowhere, which ended apparently when the jet with 239 people on board ran out of fuel, matches an entirely different, rare but not unknown scenario: that of an aircraft flying on autopilot for hours after everyone on board is dead or incapacitated.
The 26-nation search is now in its 12th day, and is focused on the southern Indian Ocean because no trace of the aircraft has been found on land. The FBI has now joined forces with Malaysian authorities in analyzing deleted data on a flight simulator belonging to the pilot, Zaharie Ahmad Shah, although it was not clear whether investigators thought the deletion of records unusual.
The anguish of relatives of the passengers boiled over Wednesday at a briefing near the Kuala Lumpur airport, the starting point of the Beijing-bound flight. In a heart-wrenching scene, one woman was dragged away, weeping and screaming."I want you to help me to find my son! I just want to see my boy!"
Flight MH370 disappeared from air traffic control screens off Malaysia's east coast at 1:21 a.m. local time on March 8 when its transponder was switched off less than an hour after take-off.
Few aircraft disasters have proved as puzzling. The Amelia Earhart era of flights simply going missing – lost at sea or in remote terrain, not to be found for decades – have long since passed. Even the two-year search for the "black boxes" from 2009 disappearance of Air France Flight 447 over the Atlantic in 2009 centred on the area where floating debris was found within hours of the plane's disappearance.
In the case of MH370, a failed hijacking may have gone awry. But another insidious enemy lurks in the hostile world 10 kilometres up where the air is too thin to breathe and frigidly cold. Hypoxia or oxygen-starvation can render people unconscious within seconds, and dead in minutes. The air masks that fall from overhead in modern jetliners supply only a few minutes of life-sustaining oxygen. So when an aircraft loses its artificial atmosphere, perhaps because a window seal fails or a bullet blasts a hole in the thin aluminum fuselage, pilots must dive the aircraft down to a few thousand metres above the surface where the air is rich enough to breathe or everyone will die.
Hours of inexplicable silence from a modern passenger jet, still flying, matches previous cases of hypoxia or oxygen starvation as a result of the aircraft losing its internal atmosphere at altitude. It has happened before, dooming other jets and all on board and it may have happened on MH370.
In 2005, a Helios Airways Boeing 737 – much smaller than the Boeing 777 but also a modern twin-engined passenger jet designed for high-altitude flight – suffered a slow depressurization as it climbed out of Larnaca, Cyprus, bound for Athens. Although warnings sounded and the oxygen masks dropped as the aircraft climbed through 6,000 metres, the flight crew failed to correctly identify the problem.
Within minutes, everyone on board was incapacitated as the aircraft climbed as programmed to 10,000 metres and followed its 90-minute flight course to Athens. Frantic attempts by air traffic control to call the apparently unconscious flight crew failed. The doomed aircraft with 121 on board then spent more than an hour circling in a programmed holding pattern as Greek F-16 warplanes flew close alongside. The fighter pilots could see the Helios co-pilot slumped over the controls; oxygen masks were dangling in the passenger cabin.
Aboard the Helios flight the insidious incapacitation caused by hypoxia happened on a relatively short daylight flight. Fuel ran out after three hours. If the same sequence doomed MH370, then the fuel on board would have provided a flight time that ended soon after the last "handshake" from the Boeing 777's satellite communications system.
With a report from Associated Press.