[WalterBright]

The pilots would have seen the nose down action as an uncommanded stabilizer trim movement. The solution is to shut off the power to the stab trim. This would work and would require no knowledge of the stall avoidance mechanism.

[sokoloff]

Exactly this. Following the existing memory items and QRH checklist items taught to every 737 pilot is (very, very likely) enough to overcome this contemplated scenario of a runaway trim from a flaw in the stability system. (It's remotely possible that the crew holds no blame in that they followed the checklist properly and the cutout switches were defective or the checklist response was otherwise insufficient.)

[JshWright]

It's also possible they were simply overloaded by a misbehaving aircraft in very busy phase of flight. Would it have been technically possible for them to recognize and correct that issue? Maybe (obviously we don't know enough to make that call), but even if that were the case, I think "blame" is pretty strong word to use in evaluating the pilots' actions in this accident.

[bronco21016]

Would runaway trim be the thing they were reacting to? It seems to me the trim was pitching down due to the design of the stall system. I’m imagining they were getting erroneous stall warnings due to the AOA sensor feeding bad data. If I’m in an aircraft and I’m getting stall warnings, stick shakers, and stick pushers I’m definitely not going to run runaway trim memory items.

[sokoloff]

It's pretty likely that they weren't reacting to runaway trim; on that we agree.

The trim wheels are large, painted mostly black with alternating, offset white stripes (so the motion is quite visible), and have a very distinctive clacker on them. https://www.youtube.com/watch?v=cQirIH_DuAs

It's possible that the crew fought to keep the airplane in a basic attitude flying configuration for several minutes without ever noticing the trim in motion unexpectedly, but that seems unlikely, particularly when the act of holding the nose up to hold attitude was accompanied by increasing nose down trim.

Minor note: there is no stick pusher in the 73. Those tend to only be installed on T-tail aircraft. Synthetic elevator feel increases, but no pusher only a shaker.

[WalterBright]

Here's a picture of the cockpit, showing the location of the power switches, trim switches, and the wheel that turns when the stab trim is running.

I find it hard to understand how the pilots would not know the stab trim was moving, and how to cut it off.

https://www.nytimes.com/interactive/2018/11/16/world/asia/li...

[augustz]

One question I have: on Boeing how easy is it to just jump down to secondary law to give up some of the flight envelope protections. Can that be switched manually? How exactly does that look?

If you know computer is getting garbage data / plane acting in an unusual way, you can dial things back. These planes and their engines are so reliable and maintenance is usually so good that it seems you could fall back to closer to direct law flying (power setting / pitch / etc) and at least keep plane out of the drink / gain some altitude.