Hello everybody:I have a confusing issue. I've noticed my aircraft (all models) no longer stick to the GPS course, but rather swing from port to starboard along the GPS route.In addition, my compass/GPS heading indicators gradually swing WAY out of alignment - as far as 180 deg.!!!!I am not sure what is causing the symptoms.My system:Pent. 4 running at 3.0 gigsXP SP2FS9Nvidia 58001 gig ramFlight Yoke/pedalsTrackIRVoice BuddyGround Env. 1.6Can anyone come up with ideas for cause of issue?Or a fix?Thanks for all the help, guys!Clayton

Hi,>>>I have a confusing issue. I've noticed my aircraft (all models) no longer stick to the GPS course, but rather swing from port to starboard along the GPS route<<>>In addition, my compass/GPS heading indicators gradually swing WAY out of alignment - as far as 180 deg.!!!!<<

I've read through the forum deeper this morning.I noticed that SUMUv3 is causing similar issues (I did install it last week) with some users, although they mention FS2002. Some say it is causing the issue in FS9, as well.I aim to remove it when I return from my trip and see if that is the culprit.Thanks again Andy!Clayton

So I just couldn't wait...I went ahead and uninstalled SUMU v3, and, voila, issue corrected!!!I'm back, baby...and this time, I know which direction I'm flying! Watch out up there!Talk to you soon.Clayton

Hello Clayton!Glad you're back in business. I discovered the root cause of this issue the other day and just to let you know, it appears that the SUMU1.bgl file that comes with the SUMU scenery package is corrupted and is the cause of the problem - for some reason it wreacks all kinds of havoc with headings all over the world in FS2004. Pretty weird, but glad we could find a solution. In the mean time, if you like to fly to SUMU, there are other pretty good freeware addons for it here on AVSIM.Happy Flying!Sincerely,Dennis D. Mullert

Hi,Ahem... glad I could help;) Andy.