Hopefully someone has an answer. I'm at a loss. I'm flying the 747 and 737-600/700 on FS9 on Windows 7 64 bit.  All of a sudden, lately, neither one will hold a course using LNAV on the auto pilot. They continuously drift to the right, about 3 to 4 miles for every 10 flown, even with a quartering wind from the right. . I have uninstalled and reinstalled both. FSUIPC has been reinstalled with the most current version, and turbulence is disabled in FSUIPC and the sim options.  My LevelD 767 does not have the same problem. If anyone has any ideas, I'd be happy to hear them.

 

Matt Collins

Try to disable winds aloft.

 

 

They continuously drift to the right, about 3 to 4 miles for every 10 flown, even with a quartering wind from the right.

 

This is a pretty well-known issue, and there are a bunch of threads out there with more detail, should you want to dive into them, but the long and short of it is how the aircraft interacts with weather.

 

Disabling turbulence is only the first step.  If you use an add-on weather program, you should operate it in DWC mode, or similar, to avoid any overcorrection issues.  Otherwise, if your version of FSUIPC is registered (I forget if "disable turbulence" is a reg feature or not since I registered mine so long ago), you can also enable wind/pressure smoothing there.  That will eliminate the issue.

 

 

 

I have uninstalled and reinstalled both.

 

As part of my normal campaign to stomp out the idea that uninstalls/reinstalls solve everything, I have to point out that this can end up causing more issues than it attempts to fix, so please save it as a last resort next time.

While it may be a well known issue, none of the prescribed fixes appear to work. Tried the magdec replacement as well.  Kind of funny to watch the icon track 30 degrees left of course and fly sideways along the route.  Some suggestsions in another forum say it could be a scenery file for an obscure airport causing the problem, but seeing as I've got around 300 sceneries installed (I've been at this awhile), adding and removing each is not a realistic option. It's suggested that moving the magdec to it's own folder and giving it #1 priority, but I think that will only fix mag variations on the ground. I have noticed that though my LVL-D 767 is tracking the route properly, when I assign a heading, it track 5-10 degrees off course too.

 

The solution of turning off the winds aloft seems kind of counterproductive. Kind of takes the fun out of planning based on winds aloft.  Kind of like saying the autoland works great as long as the weather is CAVU.  But that's me.  Back to more digging.

 

Matt Collins

Its not a weather issue!

Its an AFCAD issue. I had the same problem a long time ago at the time the 747 was released 2005. 

 

The trouble maker was an bad AFCAD file for fs2002. 

 

Solution: 

 

Disable all Add On scenerys and check if the aircraft is flying correct. Then, enable the add on scenerys step by step to find the bad AFCAD. 

 

 

The reason why you don´t have the problem with the LEVEL-D 767 is because it has its own magvar model. 

 

PMDG uses the default or updated magdec.bgl file. The bad AFCAD Files are  interfering with it and create this problems. 

 

The best area to test, is far up in the north. I was flying at Ketchikan PAKT when I discovered the problem 2005. If it behaves OK here, then everywhere. 

 

 

 

Jan-Paul

In FSX I would immediatley apply the Flight1 Registry Repair tool http://www.flight1.com/view.asp?page=library (4th option down)

 

If in Windows (anything that isn't XP) you'll need to run as admin.

 

Jan-Paul's info about AFCAD's (from FS2002) is also correct.

Stll don't understand how repairing the registry would fix the problem in FS9 or FSX.  It didn't here.

 

The stray afcad sounds the most plausible. I'd forgotten that from earlier FS versions.  Sometimes scenery desginers, either don't know or get lazy and don't properly define the limits of the scenery.  That being said, putting the magdec file in it's own folder (both the original and the replacement available online were tried and gave it top priority.  Didn't help.  

 

I may have to live with it.  I have way to many addon sceneries and even more afcad files. It would take me way too much time between loading and flight setup time.

 

Matt Collins

The Windows Registry points FSX and addons that use it to where the location of various files are.

 

Quite often the addon 'looses' where certain data is, and as a result thinks that magnetic variation is 0°

 

When you are sitting on the runway, facing perfectly straight down the centreline, the Nav display of aircraft that use the FSX files will see the aircraft (the magnetic variation degrees) left or right of the actual heading.

 

In flight it will fly off course due to this mis-match...

 

I have used FS Registry Repair several times to fix this issue and it works when I do the following

 

1: Run FS_Registry_Repair.exe as Administrator (Right click - Run as administrator)

2: Run the Magnetic Variation file

3: Run FS_Registry_Repair.exe a second time as administrator

4: Run Flight Simulator

 

It's then fixed.

 

But you say you ran it and it didn't help fix the problem.

 

Again, I use FSX, so maybe there's a difference. Not sure.

Well, the testing continues. I've disabled all the scenery except default. Even disabled the addon scenery folder to eliminate all the afcad files, no weather or wind. I even disconnected the joystick and flew with the keyboard. I haven't done that since FS3!! (Yes I go back that far.)  Also tried with the default magdec file and the repair file that's available. It still drifts off course, not anywhere near as bad, but still enough to be given corrections by atc.  With no wind, I'd expect it to be spot on.  Hopefully, someone has a suggestion, because I'm stumped.

 

Matt Collins

Matt,

 

Did you run the registry fix that the others suggested above?   That has helped alot of people in the past.

 

Are you using FSINN to connect to Vatsim/IVAO, or is this everytime regardless to an online network?

Multiple times.

 

Matt Collins