It's a "roller coaster" procedure where the plane is pitched down to lessen aerodynamic forces on the stabiliser, allowing the trim wheels to be manually turned, then pitched up to regain altitude. The process is repeated as necessary until the trim wheels can be manually moved without it.
Interesting, it seems similar to how large sailboats need to head into or down wind when attempting to trim sails in some conditions? (to reduce pressure on the sails to allow trimming to be doable by hand)
Yeah, with the important difference that in sailing you lose speed (and heel) when heading into the wind, whereas a plane will go even faster towards the ground... Scary!
Yes. Mentour mentions it in the video I have posted above.
You unload the stabilizer by pitching down for a few seconds so that you can trim it back somewhat.
However, that is not something you can do close to the ground (you lose altitude, obviously) and the "vomit comet" ride won't be appreciated by the passengers neither.
