engine-eer
From a predictably solid post by lomapaseo.
"Once the actual failure rate becomes obvious in the historical useage of the system (they iced up more often than expected) then the system interaction with the ability to continue safe flight and landing needs to be examined. From my read so far, that includes the crew actions and their failure rate (to take appropriate action). I really don't know how this was taken into account (presumably it was at least considered)."
From engine-eer
"I am not questioning the current airworthiness, I understand the issue has been addressed. I don't think that the system was airworthy at the time. What I am saying is, if they were known to be junk Airbus had an obligation to have an AD issued to insure they were changed out and they didn't do it until after this crash.
I don't think it had an acronym until after 447 went in. "Unreliable Air Speed, UAS." The term gives me the willies. From the 38 logged incidents, and the asymmetrical "Recoveries" from this challenging and surprising fault, no one was ready to AD these tubes?
There was no mystery, no "Weird Fuel", the problem was patent, and challenging. People don't like surprises, eg, sudden descent, roll, and Pitch changes.
"What was that, Captain?" Oh, that was Unreliable airspeed. "How does one recover from it?". Well, it's a bit different each time, no worries".
Airbus does not write or ennable regulations, that would be the regulator's job.
If Airbus was left to write AD's, well......