Originally Posted by
thermostat
Ice would also affect the angle of attack vane just as it would the pitot tube.
The assertion that ice would affect both pitots and vanes similarly is unproven and not very well founded, i suspect.
Yes, ice (outside the design envelope) may affect pitot systems. Ice outside the design envelope may also affect vanes.
But the probability that both systems, which have some significant dissimilarity in their sensing methodology, would be similarly affected by icing is quite unlikely. Even if both systems are affected by "extreme icing", the chances that they start to be affected at the same time, and furthermore in a fashion which is complementary (so that no comparison system could spot an anomaly), appear at first thought to be small.