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Lately I have noticed that Skyvector's Flight Planning tool "Nav Log" has been showing very wrong magnetic variation corrections for particular legs of my flight plans. The corrections appear to be egregiously wrong and this has been going for at least a few months (since I've noticed). That combination makes me doubt myself, since I'd imagine it would be fixed by now.

I created an example route to show what I mean. I made the route KFRR to KLVL which goes along the 10W variation line:

Flight Plan

I included some waypoints on the way to see when Skyvector would give bogus magnetic variations. And sure enough this is the flight plan it reports:

Skyvector's Flight Plan

I highlighted in red the legs where it gives a +6 variation correction instead of what should be the correct +10. Is this just simply a bug or am I missing something here?

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1 Answer 1

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Not a bug.

VOR magnetic variation is rarely if ever realigned, and the +6° is the current alignment of the VOR FAK, probably matching what it was during installation. Realignment is expensive and would also require republishing the airways, etc.

enter image description here
FAA Chart Supplement (PDF); yellow highlight showing FAK's 6°W alignment

And below is an example of how the magnetic radial is affected by the VOR's alignment when compared with an RNAV course.

enter image description here
FAA InFO 12009 (PDF)

Related: Is my understanding of magnetic variation and declination (for a VOR) correct?

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  • $\begingroup$ Thanks for the answer. Do you know why SkyVector would prioritize the (apparently often outdated) VOR's declination rather than the local variation, which it clearly knows judging from the other waypoints? $\endgroup$
    – GolanTrevize
    Dec 24, 2021 at 16:01
  • $\begingroup$ You're welcome @GolanTrevize: unless you're using a custom waypoint, SV uses the data from the FAA's CIFP dataset (otherwise the IGRF model for custom wpts). Remember that a VOR's radials remain fixed with reference to the station, so think of them as tracks with numbers, and the declination at the time of installation is what matters. $\endgroup$
    – user14897
    Dec 24, 2021 at 16:41

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