- Hunt for missing Malaysia Airlines jet widens to 11 nations, pilot's role probedLast message from missing Malaysia Airlines plane was from co-pilot: AuthoritiesAfter missing Malaysia Airlines jet saga, changes not assuredNeed more detailed data, info on Malaysia Airlines plane: Li Keqiang tells Najib Razak
Whoever reached across the dimly lit cockpit of a Malaysia Airlines jet and clicked off a transponder to make Flight MH370 vanish from controllers' radars flew the plane into a navigational and technical black hole.
By choosing that exact place and time to vanish into radar darkness with 238 others on board, the person - presumed to be a pilot or a passenger with advanced knowledge - appears to have acted only after meticulous planning, according to aviation experts.
Understanding the sequence that led to the unprecedented plane hunt widening across two vast tracts of territory north and south of the Equator is key to grasping the motives of what Malaysian authorities suspect was hijacking or sabotage.
By signing off from Malaysian airspace at 1.19 a.m. on March 8 (1719 GMT March 7) with a casual "all right, good night," rather than the crisp radio drill advocated in pilot training, a person now believed to be the co-pilot gave no hint of anything unusual.
Two minutes later, at 1.21 a.m. local time, the transponder - a device identifying jets to ground controllers - was turned off in a move that experts say could reveal a careful sequence.
"Every action taken by the person who was piloting the aircraft appears to be a deliberate one. It is almost like a pilot's checklist," said one senior captain from an Asian carrier with experience of jets, including the Boeing 777.
The radio call does not prove it was the co-pilot who turned off the transponder. Pilots say the usual practice is that the pilot not in control of the plane talks on the radio.
Police have searched the premises of both the captain and co-pilot and are checking the backgrounds of all passengers.
But whoever turned the transponder to "off," did so at a vulnerable point between two airspace sectors when Malaysian and Vietnamese controllers could easily assume the airplane was each others' responsibility.
"The predictable effect was to delay the raising of the alarm by either party," David Learmount, operations and safety editor at Flight International, wrote in an industry blog.
That mirrors delays in noticing something was wrong when an Air France jet disappeared over the Atlantic in 2009 with 228 people on board, a gap blamed on confusion between controllers.
Yet whereas the Rio-Paris disaster was later traced to pilot error, the suspected kidnapping of MH370's passengers and crew was carried out with either skill or bizarre coincidences.
Whether or not