Progressive flight control system failure and Avionics Smoke ?
From the NY Times
¨ First, there was a problem with the autoflight control computer. The jet would have been flying near its maximum speed and elevation at that time. That is the most efficient way for jetliners to fly, and it is safe, but pilots prefer to rely on autopilot systems in those conditions because if they were to ever lose control of the plane, it could be hard to regain, Mr. Mann said. The last message had to do with the spoiler elevator controller, which essentially controls the flaps responsible for pitch and roll control. The computer controlling these failed as well.
“It looks to me like you have a progressive flight control system failure,” Mr. Mann said. It is over the course of two minutes, which might have seemed like an eternity on that plane, but is relatively fast.This is also the moment that the plane left Greek airspace, and at 2:29:40 a.m., Greek controllers lost the aircraft’s trace, just inside Egyptian airspace, about halfway between Crete and Egypt.
Around this time, the plane made a 90-degree turn to the left and then a full circle to the right, dropping precipitously to 15,000 feet from 37,000 and then plunging again to 9,000 feet before it disappeared from radar.
The crew never gave any indication of a technical problem or other difficulties on board, even during the final, fatal minutes when the plane itself was transmitting data indicating a catastrophic failure.
One former crash investigator said that radar evidence pointing to a series of sharp maneuvers in the moments before radar contact was lost suggested that the plane was almost certainly not under the control of the pilots. Whatever upset the Airbus was so sudden and violent that it could not be compensated for by the plane’s automated safety systems.
“In my mind, this basically opens two axes of possibility: either a sudden technical problem or some kind of illicit or terrorist act,” said the expert, Alain Bouillard, a former chief investigator for the French Bureau of Investigations and Analyses.¨