A high-altitude stall followed by a hard fall before impact with the ground: China Eastern’s Boeing 737 exhibited “very unusual” behavior before its crash on Monday with 132 people on board, notes an aviation safety specialist .
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Jean-Paul Troadec, former director of the Civil Aviation Safety Investigation and Analysis Bureau (BEA), stresses that it is “far too early” to draw conclusions, just hours following the disaster which involved a type of aircraft that was widely used and considered reliable, in a country where aviation safety is “excellent”.
“On the Flightradar site, we see that the plane, which was at cruising altitude (nearly 9000 m above sea level, editor’s note), suddenly dived at around 600 km / h towards the ground before crashing. It’s very unusual, a single stall wouldn’t give that kind of profile at all.
Let’s imagine that we stall at high altitude, at which point the pilot nose dives a little to regain speed, and the plane slowly resumes its flight. These are maneuvers that we learn in the first hours of flying lessons. A stall at high altitude, it catches up very very well. There, it is something else.
It might either be the autopilot which would have ordered a sudden descent of the plane and which would not have been caught by the crew, which seems a little surprising given the duration of the fall, three minutes, that can also be an action of the crew, but nothing more can be said.”
“The Chinese have a very competent investigation office, they must be able very quickly to recover the flight recorders (data and voice, editor’s note) which normally survived this shock, and from there, not only to reconstruct precisely the trajectory, but also the parameters of the plane, the conversations of the pilots, all the actions that may have been performed on the controls… This should be known very quickly.
Personally I have never been confronted in my career with this kind of event, it is much too early to draw conclusions.
“I have never heard of any particular problem on this model of plane, it is a derivative of the very old Boeing 737, but on which we have installed modern engines. The plane did not undergo the same type of evolution on the flight controls as the MAX (at the source of the two accidents, editor’s note).
As for the level of security of Chinese civil aviation, it is quite excellent.”
