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.
This is nonsens. Certification is a desktop exercise. You go through the aircraft systems schematics and make a risk analysis about what if then. It is not about trying to let something emerge.