Originally Posted by
tdracer
The short answer is that some level of redundancy would probably have been required to meet the 10-7 requirement - there is sometimes a case for a single thread "Hazardous" system, but you need reems of historical data to back up the reliability claims - the AoA sensor simply doesn't have the level of reliability. Catastrophic must have redundancy - both the FAA and EASA are on record as not accepting probability arguments for single failures for systems with catastrophic consequences.
In addition, if the system had been judged to be Hazardous or Catastrophic, it would have received far more scrutiny from the feds - since 'Major' is considered to be a big deal, they don't tend to look at them very closely.