Those switches completely turn off the electric trim. Including the manual electric trim buttons on the yoke. The fully manual system is slow and impossible to use under load. The plane had no means to deactivate MCAS. Only to cripple it by killing the trim motors. And that is the number one reason why those planes crashed. I know that in the second crash the pilots turned off those switches but they could not regain control of the trim. So they turned them back on to regain manual electric trim. When they did that then MCAS also regained control and crashed the plane. If they had not turned those switches back on then it is very probable that they also would have crashed(In a longer amount of time). because of where the trim already was set way off from where it needed to be.
I defer to your expertise in this. Sounds like a fatally flawed system.
CC
Long before the 737 MAX problems the 737 200-300s had tail rudder malfunction caused crashes.
And that was before the bigger engines and trim changes were made on the MAX. -Tom
I read that with any kind of speed with high velocity air over the stabilizers the trim wheel is extremely difficult to turn . Could require both pilots to turn.
And with female pilots?