Hi Guys,Have an allignment problem with both the 747 and 737. The a/c does not stay on course (Magenta line on the Nav Display) it deviates almost immediately after take off to the left on the Nav Display and will stay there the whole route. I am using the Navigraph Airracs, tried several and the problem remains. I also tried an IRS allignment but that was also unsuccessful. Had a look in the Forum but could not get a probable cause and answer.Your assistance is appraciated.Willem Clack

Willem,What autopilot modes were active? Any screenshots to share with us?Cheers,

Hi Mats,Used left Autopilot with Lnav engaged. See the attachments for the screen shots.RegardsWillem

Wilem,Is this happening all the time or just on this specific departure? If it's just this specific one it's probably being caused by the psuedo-waypoints at the start.Btw, why no A/T or VNAV?

Hi Ryan,Thanks for replying. No it is happening at all airports and also during the flight itself. I just set the aircraft up to simulate the problem and forgot to arm the A/T, seldom uses the VNAV as I am flying on IVAO with ATC.Hope you can help, Regards.Willem

Hi All,Any idea on solving this problem or the cause will be appreciated.Thanks and regards.Willem

Willem,I am clueless. But if my memory serves me right I have seen other people looking at these areas:1. Erroneous navdata2. Bad/Missing/Duplicated AFCAD files3. Missing or bad magdec.bglUsually it boils down to something outside the PMDG aircraft. Any new additions installed?Sorry I can't be of more help,

Mats,Thanks, will try.RegardsWillem

Hi Mats,Tried your suggestions and still not working, seems I will have to re-install the 747 and 737 again, not what I want to do, but it seems I have no choice.RegardsWillem

Willem-Normally when we see this- it is the result of a bad AFCAD file in a scenery addon...Unfortunately- a scenery designer will occasionally make an error- not realize the impact the error will have on addons...Might be worth examining any scenery you've put in recently..

Hi Robert,Thanks for your feedback, I think you may be right there, will have a look and report back.RegardsWillem

Hi Robert,I re-installed the 737 and 747 and everything is working again.Thanks and regards.Willem

Pilots, I'm having the same trouble with mine, it just won't hold the flight path. I've updated AIRAC cycle and SIDs/STARs, removed some sceneries, and cycled the IRS yet still wants to veer off course. Hate to have to reinstall... any other ideas?Thanks, Eric, WTR*513

Make sure you input the position of the aircraft in the fmc and not of the airport starting at.This happened to me once, drove me nuts...Ed

I have seen this problem reported a few times here and it seems that most of them solved it by re-intalling the aircrafts.Bat