CDI Error

[elsmoko]

Hi Pete,

This problem is most likely caused by installation of other 3rd party

FS2004 software but I'm trying to troubleshoot to avoid a un/reinstall

of the sim (and FSNAV and other goodies).

Problem > NAV 1 VOR CDI needle indicates approx 2.5 degrees left

when I'm "on course" and the FS GPS path (flight plan generated)

and FSNAV match (show me "on course") . Any advice to correct

this problem would be greatly appreciated.

Do you happen to know what file(s) store the data used to control the

CDI needle? Is there one (general) file for all aircraft or does each

aircraft have it's own unique NAV 1/VOR/CDI data.

Many thanks for of your very fine FS utilities.

Best regards,

Ken Boardman

elsmoko@cox.net

[Pete Dowson]

Problem > NAV 1 VOR CDI needle indicates approx 2.5 degrees left

when I'm "on course" and the FS GPS path (flight plan generated)

and FSNAV match (show me "on course") . Any advice to correct

this problem would be greatly appreciated.

The CDI deviation is just another variable provided by the simulation engine. Are the segments of course short? There may well be small errors in the great circle calculations which will show up as such errors on longer segments.

But I don't use either the FS plans or GPS nor FSNav so I've no experience of their accuracy or otherwise. The CDI is likely to be more accurate as it derives directly from FS's real time simulations. BUT check this on a default aircraft -- other gauge implementations may differ.

You may get some more help in the FS2004 Forum, too, where there's a wider range of users I think.

Do you happen to know what file(s) store the data used to control the CDI needle? Is there one (general) file for all aircraft or does each

aircraft have it's own unique NAV 1/VOR/CDI data.

All NAVAID position and frequency data is contained in the scenery. For VOR radial deviations the CDI is calculated in real time based on the position of your aircraft, the position of the VOR and the selected radial. Naturally, as you get closer and closer to the VOR the radials become closer and therefore minor deviations look more and more significant. When you are quite close the VOR radial indications become almost useless because the radials are too close and you are above the VOR rather than so much laterally spaced from it. It is normal to ignore VOR deviations when close, just maintain heading and resume the opposite radial well after crossing.

How that all works when using the GPS to set the course I really don't know.

Regards,

Pete