Glider pilot here. I have decent knowledge of aerodynamics, but have never studied large jets in detail. This is my personal theory - essentially what lies behi

Glider pilot here. I have decent knowledge of aerodynamics, but have never studied large jets in detail. This is my personal theory - essentially what lies behind the words of a few articles I have read over the last few days, but the authors haven't been able to formulate it clearly. Assuming that the autopilot and fly-by-wire systems were somehow compromized, a full stall in the "Coffin Corner" (Q-corner) would be a very, very serious condition. A stall causes the nose to drop and speed to accumulate. Since the difference between the stalling speed and the never-exceed speed is so small at the altitude in question, this accumulation of speed could easily cause the plane to exceed its critical Mach number, causing supersonic shockwaves around certain parts of the airfoil. In planes not designed for supersonic flight, these shockwaves will eventually cripple the effect of the control surfaces. If the plane is in a nose-down position when it looses effect on its elevator rudder, the plane will overspeed and eventually suffer structural failure (essentially meaning the loss of some critical part) due to flutter (resonance in parts of the airframe) or aerodynamic stresses. A stall during normal flight conditions doesn't have to be a serious problem, but these weren't normal flight conditions. And the information that we have suggests that certain Airbus models have had problems with their pitot (speed measurement) systems in icing conditions, leading to erroneous speed readouts. The fly-by-wire system, which prevents the pilot from flying the aircraft into stall or overspeed, cannot function correctly without a correct speed measurement. And as I have detailed, a proper stall might be enough to doom the airplane.