Air France Crash May be Caused by Bad Airbus Design Assumptions

Something I’ve expressed concern about for the past 10+ years are the terrible assumptions being made by some engineers in the automotive and airline businesses.  Looks like those bad assumptions may have caused the crash of an Air France Airbus.

Let me say it again: Having a computer over-ride human controls is a very bad idea.


“The key ingredient most everyone seems to be overlooking: The flight control laws of an Airbus. An Airbus has flight envelope protections that cannot be overridden by the pilot. This is almost always a good thing because the airplanewon’t allow the pilot to overspeed, stall, overbank or overload the airplane. In the peculiar case of [Air France Flight] 447, the airspeed reading was inaccurate because the pitot tubes were blocked — a very rare occurrence in a jet — almost never happens.

“But when it does happen, the airspeed then acts like an altimeter: When the airplane climbs, the indicated airspeed increases, and when the airplane descends, the indicated airspeed decreases. My best guess for AF447 is that the airplane was climbing, most likely due to turbulence; I believe they were in a thunderstorm. From a pilot’s perspective, this is a bad place to be. It’s rough and difficult to read instruments. Autopilot disengages due to turbulence or ice on the airframe or pitot tubes. The airplane is climbing, and the pilot is wondering what the fuck is going on. Then, as the airplane climbs, with the false readings still indicating increased airspeed, at high altitude the margin between cruise airspeed and overspeed becomes very small, so the airplane overspeeds — or so it “thinks,” due to the false reading.”