Originally Posted by
Bbtengineer
If only the control system needed changing, then only the control system was broken to begin with.
Just because it can be fixed in software, does not mean that a software fix to an aerodynamic issue is the right solution to begin with.
When 100+ Maxes has been produced, then fixing the control system becomes the only feasible solution.
Originally Posted by
Bbtengineer
MCAS had far too much authority and not nearly enough input validation.
Correct. Before I criticize all the B737’s from the classic (Speed trim), I will mention that the B737 safety statistics is on par with A320. So despite flaws in the architecture, it’s pretty darn safe.
When you give a computer the control of the trim, then you are heading into fly by wire territory. In a FBW system you need more than input validation, you also need to validate the computation (COM/MON), and the function of the actuators (Stuck/runaway).
A well designed FBW system does the fault isolation, and eliminates the need for (some) memory items (And the risk of pilots performing them incorrectly). A badly designed FBW system kills people.