> The MCAS system was known about after the Lion Air crash, and it baffles me why pilots wouldn't have known about successful corrective action taken on the previous flight. After all, I read about this in the newspaper. It wasn't a secret.
One thing to keep in mind: it’s not like there’s a big sign popping up saying “hey, AoA is faulty, MCAS is trimming down the nose, unless you set Stab Trim switches to cutout. What do you want to do?”
Instead, you have stick shaker activation during climb out, EICAS warnings, chaos, and you struggle to bring things under control by putting the plane into a stable, manual, mode (autopilot off, flaps up, ...), and then MCAS kicks in surreptitiously, more or less (you have the trim wheels turning, but a lot of other stuff is going on), and trims your nose down.
> it baffles me why pilots wouldn't have known about successful corrective action
They did, and they flipped the stab trim switches to cutout, but they didn’t manage to overcome the required forces on the trim wheel to trim properly, and switched the stab trim back on. Now, there was the other issue with there being two stab trim switches on the NG with different function, which, if I understand correctly, would allow you to reenable the electric trim switch on the yoke while keeping the automatic stab trim disabled - but on the MAX apparently those two switches are identical, without that having been mentioned, to avoid recertification (I haven’t seen any proper elucidation of that yet - if you have two identical off switches, do you need to set them both to off, or only one, to turn it off?). I wonder (and again, haven’t seen anything about that yet) whether they flipped one of the switches back on, to get the electric trim support, deeming themselves safe from MCAS as the other one was still cut out, only to be foiled by the aircraft.
One thing to keep in mind: it’s not like there’s a big sign popping up saying “hey, AoA is faulty, MCAS is trimming down the nose, unless you set Stab Trim switches to cutout. What do you want to do?”
Instead, you have stick shaker activation during climb out, EICAS warnings, chaos, and you struggle to bring things under control by putting the plane into a stable, manual, mode (autopilot off, flaps up, ...), and then MCAS kicks in surreptitiously, more or less (you have the trim wheels turning, but a lot of other stuff is going on), and trims your nose down.
> it baffles me why pilots wouldn't have known about successful corrective action
They did, and they flipped the stab trim switches to cutout, but they didn’t manage to overcome the required forces on the trim wheel to trim properly, and switched the stab trim back on. Now, there was the other issue with there being two stab trim switches on the NG with different function, which, if I understand correctly, would allow you to reenable the electric trim switch on the yoke while keeping the automatic stab trim disabled - but on the MAX apparently those two switches are identical, without that having been mentioned, to avoid recertification (I haven’t seen any proper elucidation of that yet - if you have two identical off switches, do you need to set them both to off, or only one, to turn it off?). I wonder (and again, haven’t seen anything about that yet) whether they flipped one of the switches back on, to get the electric trim support, deeming themselves safe from MCAS as the other one was still cut out, only to be foiled by the aircraft.