Compass behavior

[silverheels2]

Hi all:
I have been away from FS for 3-4 years after starting out with FS 98, 2002, then FS 9. But I kinda just got bored with the whole thing because I just became competent in flying all the heavy iron that I drifted away. Well, now I'm back and flying the Wilco Citation x and having a lot of fun with it. There are so many nice sceneries for FS 9 of smaller airports in beautiful locations in the US and Caribbean. anyway, the reason for the post is to describe some strange (to me) behavior of the whiskey compass. The other day I had an issue with headings where the CDU headings for the flight plan being flown, the flight plan headings on the kneeboard, and the MFD headings were 10-15 degrees in disagreement. Although the aircraft went to the destination ok. But the ILS approach was wierd because the heading after loc capture was off. And the runway headings where I was flying were also "off" according to the whiskey and the MFD, and by quite a lot, say 10-15 degrees. Well, I searched the forum and found an earlier post which suggested taking magdec.bgl and placing it in the Addon Scenery folder like any other add on. Well, that apparently solved the problem with the MFD and runway headings but there is still sort of a curious behavior with the whiskey compass I wanted to bring up. It seems that the whiskey heading, which should agree with the MFD aircraft heading (not the track - but the heading, due to winds) is often off by a few degrees, say less than 5 degrees. Sometimes it is, and sometimes it isn't. I seem to recall that the whiskey does line up with the runway heading although I'll need to check that today. It's not really an issue because I don't actually fly using the whiskey, but just curious.
Anyone have any thoughts on this?

My system is 3.2 gig Pentium, 1 gig memory, ATI 9800.

[NikeHerk67]

I don't own or fly the Wilco Citation however.....

I did a quick search and came up with old (2006) discussion on the Wilco Citation in the Vatsim forum. Perhaps they've improved upon it by now, but it seems, at one time, there was a design problem. http://forums.vatsim.net/viewtopic.php?t=44645

My first thought, since I fly a lot of vintage aircraft, of course was to look and see if the "gyro drift" box was checked in the realism settings.

Best I can do......I hope you find the solution.

[jgf]

I have a similar problem, though to a greater degree, randomly with any aircraft, any area. What's wrong with this image-

[NikeHerk67]

That's a good question.
It looks like your heading should be somewhere near M370 degrees not M195 degrees, since the magnetic varation is -15.5 or so degrees, at your screen shot location.


My actual heading is T360 (degrees true) and M344 (degrees magnetic). Since the magnetic varation at KJER is -15.9 degrees or 15.9 degrees less than 360 degrees this is correct.



Sorry about the picture quality.

Edit: Adding more information

See Ronzie's response to Joe D's post. Your problem could be an addon scenery or your FSUIPC installation as well.

[silverheels2]

I've flown a number of flights since the original post and the whiskey still seems to be randomly off 3-5 degrees relative to the gyro and/or FMS and flight plan. It's not really a problem. Just curious. I have a lot of experience with compasses and electronic GPS driven moving maps on my boat. The steering compass at the helm is subject to deviation as well as variation. As you know, deviation is platform related while variation is a function of the earth's magnetic field. Now the steering compass NEVER agrees with the chart plotter precisely, off around the same as I am seeing on the whiskey. Is it possible that FS 9 is that sophisticated? remember, the FMS gets me to the destination precisely.

[NikeHerk67]

I've flown a number of flights since the original post and the whiskey still seems to be randomly off 3-5 degrees relative to the gyro and/or FMS and flight plan. It's not really a problem. Just curious. I have a lot of experience with compasses and electronic GPS driven moving maps on my boat. The steering compass at the helm is subject to deviation as well as variation.

As you know, deviation is platform related while variation is a function of the earth's magnetic field. Now the steering compass NEVER agrees with the chart plotter precisely, off around the same as I am seeing on the whiskey. Is it possible that FS 9 is that sophisticated? remember, the FMS gets me to the destination precisely.

The only way to check it for sure is to turn off real world weather. You've not specified where you're flying so it's hard to say how much the compass is off as you say. When you create a flight plan in the FS the route is not direct and the compass heading will be different from start to finish. On a flat map the plan is an arc. In the real world, such as your boat, all magnetic compasses do have deviations. If you have an aircraft the mechanic will check the magnetic compass, using an accurate compass rose painted on an apron, and they'll create a deviation card showing exactly how far the compass is off in 30 degree increments starting from 0/30/60 degrees and so on all the way around the rose.
And no, FS isn’t that sophisticated as to have compass deviations, but it would be interesting if they did.
As you probably know, not all ILS approaches are lined up directly with the runways, neither in the real world nor in FS. MS has done at pretty good job, in most cases, to create ILS offsets and LDAs.

I'd say, if your wiskey compass off 3 to 5 degrees all the time it is probably due to some add-on that is loading before the default scenery containing the original magdec.bgl created in FS9 back in 2003.

Ronzie is much more up on this subject than I am and has posted at great responses to a simular problem here http://www.flightsim.com/vbfs/showth...d-new-problems

I've done a little scenery work myself and have actually moved the center of an airport to match Earth Google's coordinates but am very careful not to change FS's original heading settings for this reason.