I suspect that, certainly at initial cert, the basic probability of total loss of the air data system was already so low that compliance was achieved without worrying about the procedures, and any procedure provided was above and beyond the basic cert requirements.
That suspicion is worth examining in more detail
If true, it puts the aircraft outside of its presumed airworthiness standards under continued airworthiness and suggests that a product change to a more reliable system or a major change to other mitigation means is needed to continue safe operations in that fleet.
I was under the impression (could be wrong
that the original design did presume a higher level of all-air-data system failures and as such adequate mitigation was presumed at the flight deck level.
Let's take another look at this.
edited due to dyslexia