The argument of Boeing for MCAS to be not "safety critical" is, that there is a trim cut out switch in every airplane, which is to be activated in case of a "tr

The argument of Boeing for MCAS to be not "safety critical" is, that there is a trim cut out switch in every airplane, which is to be activated in case of a "trim runaway" to cut of all electricity to the trimming system, including MCAS. As this is a memory checklist, every problems should be able to just switch off MCAS in case of a problem... As mentioned in the talk, the problem is, that reality differs, and the MCAS actions don't appear to the pilot like a normal trim runaway. Actually, the day before the Lion Air crash, the machine already had the same problem, but the pilots (as the story goes due to the advice of a third pilot present) did activate the cut out switch and solved the problem. That still doesn't explain why Boeing didn't implement at least consistency checking with the other sensor. And of course, we know now, how wrong Boeing was in their assumption. Unfortunately the next day, the other crew did not do this. And on the Ethiopian Air flight, they did activate the cut out switch, but way to late and didn't regain control of the machine, as it was out of trim too far.