Rendi, it's just a guess, but I suppose that certain aircraft's complex systems requires knowing where the sim is installed, and it gets that information from the Registry entry...

 

...so, if the Registry entry is missing or incorrect, bad things happen. :unknw:

 

That's the only reason I can think of that the "Flight 1 Registry Fix" might make the difference.

 

In any case, manually "fixing" the entry for Prepar3D is fairly simple and quick to do.

Thanks Fr. My point is if ILS is misaligned/mismatched with RW navdata, doesnt one need to update the airport afcad to bring it to todays heading.

To get everything to match approach plates would require a great deal more than just an updated AFCAD.

See this post I made yesterday about magnetic declination: http://forum.avsim.net/topic/436590-updating-magnetic-variation-in-p3d-2/

 

Maybe those updates can help the problem, however I note there is a warning in the readme about running the fixer exe against Airports ILS directly, as they are supposed to be set to calibrated values not actual magnetic declination.

 

I did read elsewhere that Prepar3d doesn't call up magdec.bgl, so updating each airport bgl individually may be the only way.

 

The only true way to know for sure is to find a problem airport, backup the files, and do some testing with the tools provided by that website.. 

 

I haven't got time at the moment as I'm still going through the long re-installation process for my new computer...

I did read elsewhere that Prepar3d doesn't call up magdec.bgl, so updating each airport bgl individually may be the only way.

Prepar3D 2.1 does call up magdec.bgl in ...scenery\Base\scenery - as a check test would have shown.

I have used this several times to correct the heading of PMDG MD11 on the RW and in flight....The register repair from F1 is the only way to fix that problem....unsure how it works but does fix it, no other file like magdec or any other correction helps...I have install the MD11 in P3D but can not use it as plane heading sits and fly's about 15 deg to the right.  I know it make no sense but is the only fix.

percy lee

The reason this happens is because on our older products (747 and MD-11) the FMC needs to know where the magdec.bgl file is to read the sim's magnetic variation values to use in its calculations. It has to know where FSX is to do this, so it looks for the registry entry and then finds the file from there. If it doesn't find it, you get everything displayed as true headings, without any magnetic variation correction applied - that causes the problems you see on the ND and with the AP. The newer products like the NGX and 777 find the file through a different method and aren't affected by the missing registry entry.

Thanks, Ryan. It seems my "educated guess" in reply #16 above was correct then.