Originally Posted by
jimtx
Why not just disable the system on all aircraft? If you do encounter an abnormal where you are down to manual trim the Boeing procedures don't add any caution about avoiding any flight regime that MCAS was supposed to protect.
Because they can't certify the aircraft without MCAS. At high AOA the engines (being MUCH bigger and WAY further forward) provide too much aerodynamic lift ahead of the CG, pushing the nose up even further. MCAS adds AND trim in this scenario. Just compare the B737-100 with the B737-MAX and you see why they needed to add electronic band-aids to keep it legal.