Originally Posted by
barrymung
Well, something catastrophic obviously happened!
Yes. "something" managed to apparently disable dissimilar systems.
Which implies that no dissimilar design philosophy can be foolproof.
All pitots stick out into the airflow. All are subject to icing, or to hail, or to birdstrike, etc. There is nothing you can do about that, except try to protect where you can. But you can't spec for icing massively outside the expected range, you can't build a pitot to be invulnerable to hail, and so on.
And AB aren't the only ones - indeed I'd say that it's normal for the primary air data systems to be of common design, with only (at most) a dissimilar standby system. That's what this a/c has.