The Trim key (Numpad 0) still doesn't work and I still haven't figured out how to turn off the AFCS for the heck of it. AFCS off and Vortex Rings, even though they are mentioned in the manual, do not appear to be implemented. Too bad.
I believe that section of the manual is left over from previous versions of the title. SAR1 for instance had trim, autopilot, autohover with a blip switch for speed and altitude, a working AFCS that if decoupled made life REAL interesting etc. SAR4 to my knowledge has none of that.