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I noticed on SkyVector that, for example, the Resolute Bay VOR (YRB) and Baker Lake VOR (YBK) seem to be oriented in such a way that the 360 radial is pointing in the direction of true north (and I don't think the variation is anywhere near zero there).

I know VORs are supposed to be oriented according to magnetic north, but is it common practice close to the magnetic poles to have them point true instead? If so, is there any way to tell if a particular VOR is doing just that, except looking at the chart and noticing that the small arrow is pointing north rather than off to one side?

DeltaLima
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falstro
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4 Answers4

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In Canadian Airspace, Northern Domestic Airspace (NDA) is the area of compass unreliability within which runways and NAVAIDs are oriented to true or grid north versus magnetic north.

You should not need to worry about which NAVAID is to true north; simply keep track of whether you're in Southern or Northern Domestic Airspace.

NDA and SDA

Community
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chatty
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  • Cool, how do I know which airspace I'm in, is it visible on the sectionals or something? – falstro Jan 04 '14 at 15:58
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    The Canadian LO charts shows a black line with T letters along the border. It's also clearly labelled as Northern Domestic Airspace (Compass indications may be erratic. True tracks apply). Here's an example of how it appears on the LO 5 chart. Canadian LO5 Chart – chatty Jan 04 '14 at 16:16
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VOR stations in areas of magnetic compass unreliability are oriented with respect to True North.

I don't think you can tell if it's pointing true north by looking at the charts. However, it doesn't really matter anyway because your own compass would be unreliable as well when flying in the vicinity of such a VOR. After all, when navigating using a VOR, you don't fly a heading, you fly a radial.

Farhan
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Philippe Leybaert
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    Sure you fly a radial and not a compass heading, but which one? Unless you only want to fly to the station and never leave, you might want to intercept an outbound one, makes it pretty important which way they're pointing, or you might end up discovering santa's workshop. :) And you can tell from the small arrow on the chart which way radial 360 is pointing, so it's not impossible, but that little arrow is pretty subtle, especially if you're in the air trying to figure out which radial to use when your GPS breaks down. – falstro Dec 24 '13 at 18:20
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    Incidentally his is also true of runway numbering: In parts of Canada you'll find runways numbered with true (rather than magnetic) headings because the magnetic declination is so extreme using magnetic headings is impractical. – voretaq7 Dec 24 '13 at 18:26
  • If you're flying anywhere near those weird VORs, you're either IFR or you've plotted your intended route on a chart in relation to the VOR. If your compass is unreliable you'll have to rely on GPS or VOR radials anyway. – Philippe Leybaert Dec 24 '13 at 18:27
  • Let's say you're relying on GPS, it breaks down, and you look at your chart and your plotted course, decide you want to use the outbound radial of a VOR to bring in the right direction, now should you use the magnetic or true course from your navigation log, usual answer is magnetic, which would put you maybe 20 degrees off course, which at 40 miles from the station is a 14 miles deviation. Of course you're right, but let's say I didn't note the radials and only the course; or for that matter, it's easy to miss during planning, you can't say it doesn't matter which way is north. – falstro Dec 24 '13 at 18:38
  • Let me answer that with a question: if you were flying in that area, would you be using magnetic courses and headings in your navigation log? – Philippe Leybaert Dec 24 '13 at 18:42
  • Both, I always do, everywhere. And you're probably right, it's not easy to accidentally have a VOR along your route be oriented differently from the rest. The closest I could find was Frobay to Hall beach, which is over 400 miles, the rest are all NDBs, pretty much. Still, I guess I'd like it to be more obvious that they're not magnetic somehow... and you still need to know if it points true or magnetic north, or you will dial in the wrong radial :) – falstro Dec 24 '13 at 18:59
  • If you're flying in an area where a magnetic compass is known to be unreliable, you would NEVER use magnetic headings for navigation. It just wouldn't make sense. – Philippe Leybaert Dec 24 '13 at 19:11
  • You're missing my point, you still need to know if the VOR is oriented according to true or magnetic north, or you will pick the wrong radial, regardless of how you fly. As I mentioned, Frobay uses magnetic. There will always be a border between VORs being magnetic or true, and you need to know that you're about to cross that border. This is regardless whether your compass is reliable or not, it's all about the VORs and turning your intended route into the correct radial. – falstro Dec 24 '13 at 19:15
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In areas of large magnetic declination, approaches and runways are given in true instead of magnetic headings, designated by T after the heading, such as RNAV 13T approach. If you are assigned a VOR radial, just follow that radial whether it is true or magnetic.

The important thing is that you don't use magnetic headings on a true approach. Look out for that capital T up north.

xpda
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  • Cool, didn't know about the T. If you're not being assigned a radial, but selecting one yourself, do you know if there's a way to determine if the VOR is using true north or not, except for the tiny arrow on the chart? – falstro Dec 25 '13 at 17:01
  • It doesn't look any different on the chart. You should be able to check the Facility Directory (or Canadian counterpart) for the magnetic variation. Here's some info for using one in an approach: http://www.avcanada.ca/forums2/viewtopic.php?f=54&t=78868 – xpda Dec 27 '13 at 04:00
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Even in areas where compasses are not actively unreliable, magnetic variation changes over time so that VORs and runways might no longer be aligned to their nominal magnetic bearings. Runways are usually renumbered to correct this, but old VORs are usually left in place because many charts depend on their original alignment.

As well as magnetic and true north systems, there is a "Greenwich" system used for polar navigation which is aligned to the prime meridian rather than to any local concept of "north". I'm fairly sure this is used by aircraft that overfly either pole, but there are no permanent navaids or runways that would be aligned to such a system.

Chromatix
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