RR NDB
Excellent post above
It does an exccelent job of putting perspective how reduncay works in complex systems (with the pilot) and where it might not work.
Your knowledge and understanding is way beyond the more simple use of the words by 99% of posters, you can bet that the Airbus designers have equal but deeper knowlege and understanding as well.
to wit
1. Fault tolerance (a/c)
2. Graceful degradation (a/c+crew)
One might now suspect where to look for the swiss cheese layer that has gone wrong in this accident to make this the only so-far upset accdent associated with a probable icing failure of the pitot system.
To me all this talk about poor design and reversion laws in the many many pages of these postings is way too presumptious