AF447

[einhverfr]

A few thoughts after reading the BEA report.....

First, the last ACARS positional message (around the beginning of the rapid degradation of the situation) seems to occur inside a region of strong convection within the larger meso-scale convective system. At this point, I think it is reasonable to ask why pilots flew into "that weather." Does AF require sufficent WX radar training? Are proper procedures (and training) in place to help pilots avoid at least the worst of the weather? From the available data, it does not appear that any weather avoidance was taken.

Secondly, could strong updrafts be a major factor, up to and including the final descent and crash? As I understand it, aircraft stalls are a function of angle of attack, and pitot tubes don't function well at high AoA values. A 50kt updraft at a speed of 447 kts (mach 0.78 at fl350) would add about 6.4 degrees to the angle of attack. (Showing my work: Inverse sine of 50/(447^2 + 50^2)^0.5... is roughly 6.4 degrees) Even with a 3 degree angle of attack, this puts the plane close to an angle where the pitot tubes become unreliable even without icing. Depending on the automated response to the angle of attack, this could get worse very quickly. The main point is though that any pitch up may have rendered the pitot tubes unreliable even without blockages. Oddly this gets back to what Tim Vasquez wrote about turbulance being the primary factor on his list shortly after the incident. In short could a strong updraft have caused a lack of reliable airspeed indications, degraded controls, etc?

Thirdly, what woud the autopilot have done in a strong updraft before disconnecting?

Fourth, assuming AoA was reduced by pitching the nose downward (possibly restoring airspeed data), what would have happened when the airplane went from a strong updraft to a strong downdraft? Could this have also caused a stall of some sort via too low of an AoA?

So this leads to a couple of other questions that are now lurking in my mind:

1) Can we shelve the idea that pitot icing was a factor at this point and focus more on AoA issues?

2) Could the Cabin Vertical Speed advisory have referred to a falling descent? Could this be some sort of stall?