At 2:26 a.m., a message indicated that the right cockpit window has been opened. This could have been done to vent smoke, Mr. Mann said, or something else could have cause the breach.
Over the next two minutes, there were two smoke indications, one in a bathroom and another in the avionics bay, the part of the plane where much of its electronic equipment is housed.
Mr. Mann cautioned that these messages did not necessarily mean that there was a fire. The messages could also have been triggered by rapid decompression of the aircraft, which can produce condensation that the plane’s sensors could mistake for smoke.
Finally at 2:29, there were two more alerts having to do with the plane’s flight control computer systems.
“The last two are troubling,” Mr. Mann said. “You are starting to really see things rapidly degrade.”
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 completely safe, Mr. Mann said, 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. That is why pilots sometimes call those conditions the “coffin corner,” he said.
The last message had to do with the spoiler elevator controller, which essentially controls the flaps responsible for controlling the pitch and roll of the airplane. A computer controlling the flaps failed as well.
“It looks to me like you have a progressive flight control system failure,” Mr. Mann said. It appeared to take place over the course of two minutes, which might seem like an eternity on that plane, but is relatively fast.
