A very sad thing is that the MCAS has no off switch. The only way to stop if from controlling the plane was to cut power to the electric motors that run the trim. However doing that also means that you can’t use the electric manual controls mounted on the Yoke. So the pilots were never able to gain manual control of the planes trim. Full mechanical manual control was not an option due to the forces at work.
It appears that the fatal moment came when the pilots restored power to the electric trim motors(in an attempt to regain use of the yoke controls), and the MCAS system was then able to instantly put the plane into its unrecoverable fatal dive. It had actually never stopped trying to crash the plane, as the data log shows. MCAS had no idea if it had control of the motors or not.
So they in the process of make several changes to the software. All of which should have been in place to begin with. I think those changes will help a lot, but I believe that the software will still be lacking certain types of error checking, and suicide prevention calculations. But at least it will be much more difficult for MCAS to remain on line if there are problems.
The fact is that this software was not fit to run a coke machine, let alone an airplane.
“The only way to stop if from controlling the plane was to cut power to the electric motors that run the trim. “
The yoke trim button over-rides MCAS.