This question is directed to pilots of the big iron, at heavy landing weights, specifically the MD-11  carrying about 90 tons of payload.

When the autopilot has captured the localiser and the plane is configured for the approach, does the autopilot run out of available stab trim?

I would suspect that the answer is a definitive NO! I also suspect the autopilot uses elevator input in conjunction with stab trim.

I think one of the issues within the SIM (FSX:SE) is that the autopilot controls pitch using stab trim alone even if the aircraft has elevators too.

(Yes, it seems that I appear to have found another of Sky Sim's MD-11 foibles..)

Thanks.

Maybe the CG is too far forward due to wrong loading? Another reason would be a too low approach speed. Theses are the only two reasons I can think of why you could run out of stab trim, regardless if the elevator is being used as well or not.

Edited November 11, 20196 yr by FDEdev

The CG was quite forward at around 20%, but still within limits according to the Sky Sim manual (12-34%).

I've revisited the cfg file with a "fudge" which at least seems to look "correct" when compared to the real thing. htail_incidence is now -1 rather than +2. My initial findings are at the end of my screenshot thread: https://www.avsim.com/forums/topic/563326-lima-to-miami-mad-dog-cargo-time/?tab=comments#comment-4105550

I shall carry out some more flights to see if this setting is good enough dynamics-wise, or if it is TOO good 😉