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Although VOR stations follow magnetic north, do VOR's on a chart follow true north?

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    $\begingroup$ Which charts are you asking about? $\endgroup$
    – Pondlife
    May 11, 2020 at 1:46
  • $\begingroup$ They are set to magnetic north, but magnetic north at the time they were instituted. So if a VOR was buit in 1968, it would point at the location at which magnetic north existed in 1968, and if one was built today, it would point at the current magnetic north (5 year model). The VOR's orientations aren't updated over time. $\endgroup$
    – Ryan Mortensen
    May 11, 2020 at 5:01
  • $\begingroup$ Aeronautical charts $\endgroup$
    – Lungelo
    May 11, 2020 at 12:04
  • $\begingroup$ @Pondlife. When I asked this question I was talking about Aeronautical charts that are, for example, 1:500 000. But I would like to know about 2 types of charts; aeronautical charts and plotting charts (where only radio stations, isogonal lines and lines of longitude and latitude appear). So finally, my question is, which orientation do VOR's follow on aeronautical charts and plotting charts? Any help would be appreciated. $\endgroup$
    – Lungelo
    May 11, 2020 at 12:18
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    $\begingroup$ @RyanMortensen - according to the FAA, if the charted North of the VOR and the actual magnetic North are off at least 6°, the FAA will have all of the aeronautical charts updated. $\endgroup$
    – Dean F.
    May 18, 2020 at 13:49

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As per the FAA's legend they are referenced to magnetic north

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Compass rosette will be based on the five year epoch magnetic variation model.

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Both the signal and the representation on the sectional chart of a VOR will be oriented to magnetic North. There will be some fluctuation caused by magnetic drift. Adjustments will be made for this.

According to the FAA FAQ website...

Why is there a difference between the magnetic variation for the airport and the VOR located at the same airport?
When a navaid is first constructed, the antenna is physically oriented to True North. Then a potentiometer adjustment is made to slave the navaid with Magnetic North. This action matches the isogonic line making it agree with a magnetic compass. Initially these two values are the same, but the magnetic variation of the earth changes at differing rates depending upon location and time.

Navigational aids go into service and remain online 24 hours a day, 365 days a year. The FAA performs periodic maintenance; however, readjustments to match the isogonic value require a total shut down of the equipment, plus recertification and flight check verification. This process begins when a navigational aid is out of tolerance by at least +/-6 degrees. GPS databases use a MAGVAR model to calculate the most up-to-date magnetic variation.

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  • $\begingroup$ one of the comments says the VOR headings are not updated as magnetic north drifts--?? $\endgroup$
    – quiet flyer
    May 11, 2020 at 13:10
  • $\begingroup$ @quietflyer - The FAA website states that the VOR headings are updated after they reach a certain tolerance. $\endgroup$
    – Dean F.
    May 18, 2020 at 13:30

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