Why are journalists still calling this an 'anti-stall' system. It's not, and it's so deceptive about what it actually does. The crashes had nothing to do with stalls, the system does nothing to prevent stalls, and the safety regulations that brought it about are only indirectly related to stalls.
The system affects how the flight stick feels and that's really it. The more you pull up (higher AoA), the more force is needed on the stick. That's supposed to be linear within some margin of error. The big fat new engines took it out of the linear envelope, making it a bit lighter than it 'should' be at high AoA as the engines caught the wind. They either fixed this, or else needed a new type rating (pilots can't hold more than one, so it's a huge issue for existing operators of 737s).
The solution was MCAS which, as originally designed, wasn't powerful enough to cause problems. But test pilots said that the stick was still a bit light, so they reworked it and made it way too strong, while still being invisible to pilots and lacking the reliability of a critical system. Then several hundred people died.
> system affects how the flight stick feels and that's really it
I kept hearing this too, so I wondered why they didn't just directly change how the stick feels, like with a force feedback system?
And I looked it up[1]: Turns out MCAS was also there to push the nose down at high AoA, to imitate what the 737 NG does even in the absence of control input, so it's not just a stick feel thing.
"The added nose down trim has the side effect of requiring more elevator input at high angles of attack", so simultaneously fixing the stick feel issue.
It seems to me like MCAS solved two related problems at the same time... and sadly thus created an even larger unintended problem.
The system affects how the flight stick feels and that's really it. The more you pull up (higher AoA), the more force is needed on the stick. That's supposed to be linear within some margin of error. The big fat new engines took it out of the linear envelope, making it a bit lighter than it 'should' be at high AoA as the engines caught the wind. They either fixed this, or else needed a new type rating (pilots can't hold more than one, so it's a huge issue for existing operators of 737s).
The solution was MCAS which, as originally designed, wasn't powerful enough to cause problems. But test pilots said that the stick was still a bit light, so they reworked it and made it way too strong, while still being invisible to pilots and lacking the reliability of a critical system. Then several hundred people died.