Re:Boeing 737 Max: Automated Crashes [video]
by kayfox on Monday December 30, 2019 @05:48PM
(#21917387)
Correction on the Ethiopian flight: They activated the trim cutout, were able to regain most control, and then deactivated it, presumably to adjust the trim, tested that they had trim controls, and then something happened to distract them from trimming it correctly and then cutting it back out.
Had they left it cut out, they would have been able to keep it under control, had they adjusted the trim and then cut it out, they would have been in a decent position to come back and land. It will be interesting to see what the investigation finds about why it was cut back in and then left.
Re:Boeing 737 Max: Automated Crashes [video]
by xvf22 on Monday December 30, 2019 @06:53PM
(#21917782)
In previous models you could cut out the auto trim while still having electric trim on the yoke enabled. Sadly in the MAX Boeing decided to get rid of this feature which would have been pretty damn useful for these crews.
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.