Originally Posted by
Loose rivets
Given that MCAS was rewritten is in my opinion the most serious issue in the whole debacle. Yes, taking the data from a single unit broke the rules about one item being able to cause a 'catastrophic' incident, but I'm not quite clear if it would be deemed so if MCAS had not been rewritten. It took the latter to qualify the former. Perhaps.
But the hazard analysis said it was a major hazard, not catastrophic, and a single input is acceptable for a major hazard.
The analysis was wrong/incomplete, as the NTSB noted. But that's what the team was working from when they modified MCAS.