[mikejb]

I've seen different reports about what's in the training. I think the challenge here is to detect that the system is running haywire and then disabling it. It's not a common situation, never trained, and possibly only something the pilot might have read on the way to the airport. Not ideal for a high-stress situation.

[WalterBright]

On the 737 airplanes, when the stab trim is running a wheel on the side of the center console turns and makes a loud clacking sound. It is designed to be obvious.

You can see a picture of the wheel here:

https://www.quora.com/What-are-the-spinning-wheels-in-an-air...

[mikejb]

You have to make the connection though: that clacking noise is probably that new system I read about doing something. Then you have to determine whether that system is the cause of the problem, and whether disabling the system will either fix the issue, or possibly make it worse.

[WalterBright]

The clacking sound happens whenever the stabilizer trim is in operation, which is frequently, and has been in 737s for decades.

The pilots would be very familiar with the sound and what it represents. The trim wheel also spins when the trim is running, a large and obvious indication (I posted a link to a photo of it).