Originally Posted by
DaveReidUK
Yes, that the same defect apparently persisted through four consecutive sectors, and successive crews were in effect testing the outcome of failed rectification attempts, is inexcusable.
That said, an "inherent and unknown programming defect" (in any software environment, not just aerospace) by definition requires a specific, unforeseen combination of factors (possibly including other defects) in order to trigger it. It's entirely possible that the required combination of factors never emerged during the certification process.
If there had been precursors to this issue, while we might not have heard about them prior to the crash, they would undoubtedly have emerged in the last 10 days.
AFAIK, none have.
Failed rectification attempts of hardware yes, in attempt to solve a problem that appears to be deeply hidden within the product systems design or 'likely to exist or develop in other products of the same type design', as the AD seems to suggest.