>This is where Boeing messed up big time. According to the article they only had 2 AoA sensor, completely missing the fact that what happens if one sensor fails

>This is where Boeing messed up big time. According to the article they only had 2 AoA sensor, completely missing the fact that what happens if one sensor fails and which is correct. No, you missed something really critical in all this. There are 2 AoA sensors, however only 1 of them is used as input for the MCAS system. There was no redundancy whatsoever! The proposed software patch will use both AoA sensors, and light an indicator light if they disagree. They don't want to retrofit the planes with 3 sensors like Airbus, because obviously Boeing cares more about profits than safety and good engineering.