Doggzilla
Well-Known Member
One of my friends was looking over the trim system on the MAX and noticed that a potentially fatal change in switches matches the behavior of the pilot in the most recent crash, and explains both crew's mistakes.
The layout of the trim control switches has been changed from the older models and pilots likely did not notice the change if they weren't specifically told.
On older models the right switch controls the autopilot trim and the left controls the pilot trim.
On the MAX they are changed with primary and secondary instead. So a pilot trained on the older models would accidentally only turn off the secondary if he flipped the right switch in an attempt to cut autopilot trim.
On the second crash the pilot was unable to use manual trim for some reason and engaged MCAS for an unknown reason in an attempt to trim back up. This pilot was trained on the older model, and he hit the left switch that would be the pilot trim only in older models. This gave trim power back to MCAS and guaranteed a fatal crash because he was unable to use manual trim for some reason.
Seeing as how he was trained on the older aircraft where the left switch is the pilot trim only, there is a very good chance he only hit that switch because he did not realize it was the primary and would engage MCAS trim again.
On the first crash they also tried to disable it but were unsuccessful. I do not know if they only flipped the right switch, but there is probably a pretty good chance that was why, if the switch they flipped did not properly disable it.
The layout of the trim control switches has been changed from the older models and pilots likely did not notice the change if they weren't specifically told.
On older models the right switch controls the autopilot trim and the left controls the pilot trim.
On the MAX they are changed with primary and secondary instead. So a pilot trained on the older models would accidentally only turn off the secondary if he flipped the right switch in an attempt to cut autopilot trim.
On the second crash the pilot was unable to use manual trim for some reason and engaged MCAS for an unknown reason in an attempt to trim back up. This pilot was trained on the older model, and he hit the left switch that would be the pilot trim only in older models. This gave trim power back to MCAS and guaranteed a fatal crash because he was unable to use manual trim for some reason.
Seeing as how he was trained on the older aircraft where the left switch is the pilot trim only, there is a very good chance he only hit that switch because he did not realize it was the primary and would engage MCAS trim again.
On the first crash they also tried to disable it but were unsuccessful. I do not know if they only flipped the right switch, but there is probably a pretty good chance that was why, if the switch they flipped did not properly disable it.
