As additional details about the crash of Air France 447 are released, we now know that more information than was previously reported was being transmitted in real time including speed and altitude excursions, g-forces and all system read-outs, including computer faults.
Prior to the crash, Airbus had issued a bulletin instructing all crews to be certain, by comparing to global positioning systems that their airspeeds were being properly read by the computers from the Pitot-static Tubes on the nose of the aircraft. The suggestion is that these tubes can ice up in severe weather in spite of being heated. Here’s the reality – the reason for the odd airspeed differences is that in situations of severe turbulence the airspeed variations can be large because the wind direction and velocity are rapidly changing as is the flight altitude of the aircraft. In short, severe wind shear causes rapid changes in wind direction and velocity.
The bulletin makes sense but as the information trickles in, it begins to appear that severe turbulence and a breakup is more likely the culprit – a very bad ride indeed. The aircraft must be found in order to determine just what broke first – the tail, parts of the tail or the main wing box, the wing or parts of the wing. Only then will we know if the testing to ultimate load required for transport category airplanes is both realistic and stringent enough.
This never should have happened.
Lastly, there are serious limitations on weather radar on-board, as well as on those people who must interpret it. With all of the computing power on the A-330, much weather data was available to be downloaded, not only from the on-board radar but also from ground and space-based facilities as well because the computers can make a better decision on whether and how to proceed in the face of severe weather. We need to go there.
Arthur Alan Wolk
June 5, 2009