thanks Ozfarang. The pitot system I understand. It can be prone to icing and getting blocked as you know, giving false inputs to onboard management systems, disengaging auto-pilot etc. There seems to be little indication of blocked pitots to the pilots however? maybe the latest pitots have solved this? An easy way surely for the pilots to find out if the pitots were blocked would have been to blow air forward out of the pitots via an auxiliary pneumatic system? It wouldn't be difficult to detect a blockage that way? How many times have even experienced pilots been fooled into a stall when the auto pilot has disengaged due to iced pitots when flying at night with zero visual references? The Air France disaster in mid-Atlantic started because of pitot failure and the crew's total failure to react accordingly - and that's on the most modern of aircraft - scary.
I'm not sure I understand your explanation for the AOA sensors having to be outside in the airflow. Seems to me the AOA sensors are the equivalent of a spirit-level indicator? I can't quite work out how they usefully function when a plane dives? but passenger planes shouldn't be diving anyway. I need to think a bit more about this.
