I've been using the MD11 in FSX for many weeks with great success with everything functioning as it should.But in the last fortnight an inexplicable problem has occurred ... when in autoflight/nav mode the aircraft struggles to hold the programmed fmc course.During climb and cruise it will veer up to forty degrees either side of the course as it struggles to hold the desired heading.At first I thought it was due to wind shift changes (I use Active Sky Advanced) but I've since ruled this out.The aircraft has been behaving perfectly up until now and I can't figure out what's going on.Anyone else experienced this and if so what's the solution?Thanks.Frank

If it isn't wind shifts then there's not a known reason for course deviation, and wind shifts usually impact airspeed/altitude much more than heading. Maybe a screen shot would be helpful.

If it isn't wind shifts then there's not a known reason for course deviation, and wind shifts usually impact airspeed/altitude much more than heading. Maybe a screen shot would be helpful.

I think this also may be the issue described in the 744X "unknown problem" post. Do you have all of the wx smoothing functions turned on in ASA? If you have FSUIPC ensure all of the wx smoothing functions are turned on as well.

I think this also may be the issue described in the 744X "unknown problem" post. Do you have all of the wx smoothing functions turned on in ASA? If you have FSUIPC ensure all of the wx smoothing functions are turned on as well.

Have smoothing functions in ASA and FSUIPC turned on.Thought it might have been a c of g issue but that's not the case.It's a real mystery, especially as it came right out of the blue without me changing anything in FSX.Frank