[swhitt]

Manual Stabilizer Trim

Excessive airloads on the stabilizer may require effort by both pilots to correct the mis-trim. In extreme cases it may be necessary to aerodynamically relieve the airloads to allow manual trimming. Accelerate or decelerate towards the in-trim speed while attempting to trim manually.

https://www.pilot18.com/wp-content/uploads/2017/01/B737NG_FC... page 312 (8.16)

[cjbprime]

To be clear, that's a link that agrees with me that it can be impossible, not a link that says they just needed to work harder.

It's also from a 20 year-old manual, and isn't present on newer manuals, and pilots haven't trained on it in decades. Not appropriate to expect pilots to know, and possibly not helpful here: the pilots were low altitude, so allowing the nose to drop even further (to relieve aerodynamic load) may have been deadly too.

[swhitt]

https://www.satcom.guru/2019/04/stabilizer-trim-loads-and-ra... does a pretty good job of summarizing it I think. It sounds incredibly difficult to do.