To the speculators...
Scenario:
Fire/damage sufficient to disable any chance of communicating with outside world.
*Aircraft made at least four changes to its track. Fire/damage did not destroy Satcom system. No communications indicating problem. Fire/damage of that magnitude unlikely to leave aircraft in condition to fly on.
Contra-indicated.
Rapid depressurisation disabled pilots.
* Aircraft made at least four changes to its track. Transponder and ACARS Intentionally disabled.
Contra-indicated
Slow decompression was not noticed by crew.
* Aircraft made at least four changes to its track. Transponder and ACARS intentionally disabled. EICAS system would have alerted crew to high cabin pressure well before incapacitation. Cabin oxy masks would have fallen in cabin at pre-determined altitude, Flight crew would have been alerted by cabin crew.
Contra-indicated.
Aircraft shadowed other aircraft to escape detection
* Aircraft, on a moonless night, would have had to track and intercept target aircraft visually as TCAS turned off with transponder. Dark night and heavy aircraft. Neither pilot seems to be formation rated. Flight at 35000 feet, and above as target aircraft climbs, leaves no performance margin for close station keeping. Air to air refuelling of large aircraft takes place around FL250 due to aforementioned performance limitations. Air defence radars would have picked up two large paints. Aircraft required to fly dangerously close to target aircraft for many hours.
Contra-indicated.
Aircraft had emergency and tracked towards Langkawi
* Not supported by Satcom ping data.
Contra-indicated
Aircraft went north over Asia
* No record of any unidentified aircraft on various countries Air defence radars. Extremely unlikely to find, intercept and hold position with another aircraft flying between FL350-390 for length of time required.
Contra-indicated
Aircraft hijacked by passengers
*Security procedure make this difficult but not impossible. High degree of technical knowledge required to fly revealed track and disable ACARS. No evidence of any terrorist links to anyone on passenger list. Aircraft disappearance not compatible with usual terrorism objectives. Passengers and crew would be unable to enter cockpit to restore control if locked out.
Contra-indicated but possible.
Interference by flight crew
*No revealed motive to do so.
Possible.