Notwithstanding the thousands of words that have been written in Pprune about the AF447 crash, its causes seem reasonably clear, at least to me. I would suggest the following:
- Cause No 1 - A failure of navigation by the crew in allowing their aircraft to fly too close to, or through, dangerous Cb systems.
- Cause No 2 - Icing up of most, if not all, of the aircraft's pitot heads leading to the flight computers and flight crew having no source of reliable airspeed measurement.
- Cause No 3 - Based upon the information released so far, by the BEA, the flight crew did not appear to have a proper understanding of their flight situation after the automatics disconnected and hence, did not apply the right corrective actions (flying with appropriate pitch/thrust settings) which would have prevented their aircraft from stalling into the ocean.
There has been some discussion in this thread about what might be done to overcome pitot icing problems. An idea (probably crackpot) occurred to me of a pair of extra retractable 'standby' pitot heads, normally housed within the fuselage in a heated compartment, which could be deployed in the airstream in the event of the normal pitots icing up. Even if these 'standby' units only worked for a few minutes, it might be long enough for a crew to recognise that their actual airspeed was OK and that they should fly appropriate pitch/thrust settings. Also, iced 'standby' pitot heads could be retracted and warmed/de-iced within the fuselage before further deployment into the airstream.