It appears that MCAS is active during manual operation (i.e. when the autopilot is turned off). This is consistent with the idea that MCAS is meant to give the pilot a feel of the 737 NG plane.

I do not know if MCAS can be turned off during manual flight. I think it can, but indirectly and it does not appear to be known by the pilots.

The patch is part of the original design, to compensate for the unbalanced plane. I call it a ‘patch’ because its an afterthought from the original 737 design and was introduced because of the larger Leap engine.

The case I make is that its a bad design because of fundamental computer science reasons.

It is not due to conventional software bugs that are very difficult to prevent.