How to enter a deep stall
I am amazed at all the kinetic energy and OAT and such discussion here for last two days.
The profile of AF447, as we know it, and regardless of control laws or pilot inputs, resembles the classic manner of getting the Viper into a deep stall. You simply climb at a fairly steep attitude, fairly level roll attitude, and at low AoA until you run outta energy, then sit there and watch the jet try to nose over too late. AoA increases rapidly, and with little or no "nose down" pitch moment available from the flight controls, you are there!!
The jet's "protections" (or limits, as I prefer) are fooled. We simply fly past the jet's control authority to provide the so-called "protections". Worse, and in the case of the Airbus, we have a myriad of reversion "laws" that could cause the crew to do something worse than just sit there and hold attitude/power. The overspeed warning is what I am concerned about, as that could explain either pilot or computer commands, or both.
I refuse to believe that the Airbus is a poorly-designed jet from the aerodynamic aspect. I truly believe you could exceed the mach "protections" until reaching maybe 0.95M or so with no ill effects. I truly believe that you could fly the jet at 10 or 15 degrees AoA. I truly believe you could pull 3 gees without the wings falling off. I truly believe the jet has exceptional lateral stability, or we would not see a proflile with a slow rotation versus a tendency to enter a spin.
What I do see is an embedded "autopilot" influence that changes control laws depending upon flight phase ( and Viper had some of those, but not to the extent of the Airbus). I see confusing cockpit warning/caution indications. I see no firm "hang your hat on the jet's capabilities" control law that the human crew can use when things go to hell in a handbasket. Worst of all, I see no aspect of the system that acknowledges loss of air data and simply reverts to a basic control law while the crew and HAL figure things out.