Hello,I had not used my PMDG (737/747) for sometime when i yesterday noticed that my 747 was not at any time on course, it was constantly roughly 15 degress of course in LNAV mode, even between short sectors.This obvoisly has a technical rather than natural epxlanation but i cant figure out what. Please read the following.1. En route between KIAD and EGLL and around KEWR i noticed this.2. I then stoped the sim and placed my 747 on various runways, such as KEWR, ESSA, EGKK and the same thing happens. The compass heading of the Aircraft various from the acctual heading of the Runway by as much as 15 degrees att all times, i then switched to Level D 767, and that was both correct and perfect.3. I Uninstalled the whole PMDG package and reinstalled the first 737-600/700 package (with updates) and did the test. Same failure, switched to Level D again, no failure.During the years i have had the pleassure of running PMDG aircrafts i never had any troubble, i should also ad that the re-insatll i did today was the second one in short time due to a serious crash of my computer that forced me re-insatll both Level-D and PMDG, i after that re-insatll never flew PMDG untill yesterday but have flown other aircrafts such as Level D and RFP 747-200. I need some help here and would appreciate any tip.All the bestMattias

As others will verify as well, this is an issue with some 3rd party scenery product you've added which is causing your FS9 magnetic variation to be wrong.

Thank you for a swift answer that certainly did the trick. The problem was caused by "Lagos Hurghada Scenery". The question that remains is why the scenerymaket does not fix it if it affects the entire FS9?All the best/m

Why indeed...Regards,