Sectionals - Why are some VORs aligned with True?

1000RR

1000RR

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1000RR
Something I've been meaning to ask... and I noticed it originally when I was doing some solo XC's a few months back for my PPL. Now I'm planning a flight about 150nm away and was planning my route to/from some VORs and noticed it again. Most VORs are aligned as I would expect - with Magnetic North. However, some (at least a few in Florida - OMN, LBV, PHK, LAL, OCF) are aligned with True North. Is this because they have just not been field adjusted to magnetic and the radial signals coming off of it are aligned with True?
 
The declination (difference between the 0 radial and true north) may have never been set to magnetic north, or it may have been that the local variation has changed but the VOR not realigned. When you've got procedures and airways emanating from a VOR, it's not a trivial change to just change the declination.

Note, it's of little consequence as long as you know what it is. Except in degenerate conditions, the radial and magnetic heading only match at the station itself.
 
1000RR said:
Something I've been meaning to ask... and I noticed it originally when I was doing some solo XC's a few months back for my PPL. Now I'm planning a flight about 150nm away and was planning my route to/from some VORs and noticed it again. Most VORs are aligned as I would expect - with Magnetic North. However, some (at least a few in Florida - OMN, LBV, PHK, LAL, OCF) are aligned with True North. Is this because they have just not been field adjusted to magnetic and the radial signals coming off of it are aligned with True?
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Yeah, they don't re-align the VORs for magnetic shift once they are installed. (...of course, I might be wrong...)
 
flyingron said:
The declination (difference between the 0 radial and true north) may have never been set to magnetic north, or it may have been that the local variation has changed but the VOR not realigned. When you've got procedures and airways emanating from a VOR, it's not a trivial change to just change the declination.

Note, it's of little consequence as long as you know what it is. Except in degenerate conditions, the radial and magnetic heading only match at the station itself.
Click to expand...
Seems it was the former in my examples (declination never set, as these are all exactly the magnetic variation 'off') but was thinking along the same lines as you described. I haven't found it to be of consequence, just makes my numbers look off enough that I've gone back and said - what the heck is going on here... and there it is again - a VOR to True, not Magnetic. Thanks for the insight!
 
1000RR said:
Most VORs are aligned as I would expect - with Magnetic North. However, some (at least a few in Florida - OMN, LBV, PHK, LAL, OCF) are aligned with True North. Is this because they have just not been field adjusted to magnetic and the radial signals coming off of it are aligned with True?
Click to expand...
No, they are aligned with magnetic north as of the date last aligned. OMN, for example, was last done in 1965 when the variation was zero:

I tried to find the Order for you on the FAA website, but haven't had enough coffee to navigate their site. Used Fltplan.com instead (which was a bit of a challenge, too, since I don't regularly use it).
 
dtuuri said:
No, they are aligned with magnetic north as of the date last aligned. OMN, for example, was last done in 1965 when the variation was zero:

I tried to find the Order for you on the FAA website, but haven't had enough coffee to navigate their site. Used Fltplan.com instead (which was a bit of a challenge, too, since I don't regularly use it).
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Wow! Good find! I guess I just assumed (I know, bad on my part) that magnetic would change, but only slightly, and guess I was thinking it might go back and forth more and be "around" what it was originally. 7 degree change is pretty impressive.
 
flyingron said:
The declination (difference between the 0 radial and true north) may have never been set to magnetic north, or it may have been that the local variation has changed but the VOR not realigned. When you've got procedures and airways emanating from a VOR, it's not a trivial change to just change the declination.

Note, it's of little consequence as long as you know what it is. Except in degenerate conditions, the radial and magnetic heading only match at the station itself.
Click to expand...

This. And stations are recalibrated on occasion.
 
dtuuri said:
Um, it took 56 years.
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LOL, point taken. You missed my subtlety above. I was thinking the deviation goes "back and forth" and might almost wobble over time, not really continue in one direction. But yes, 56 years is some time for sure. So the deviation that's created over time continues in one direction - is that correct?
 
1000RR said:
LOL, point taken. You missed my subtlety above. I was thinking the deviation goes "back and forth" and might almost wobble over time, not really continue in one direction. But yes, 56 years is some time for sure. So the deviation that's created over time continues in one direction - is that correct?
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Variation. Depends on what the magnetic north pole does. Look up the movement of that over the past couple hundred years.
 
EdFred said:
Variation. Depends on what the magnetic north pole does. Look up the movement of that over the past couple hundred years.
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A quick Google came up with the following. Reading it leads me to believe it moves in one direction.

"The magnetic North Pole is the location in the Northern Hemisphere where the planet's magnetic field lines point straight downwards, penetrating the surface of the Earth. Its location changes at a rate of about 56 kilometers (35 miles) per year. Currently located in the Arctic Ocean north of Canada, it has recently been moving towards the north coast of Russia at an increasing speed. In any case, the magnetic North Pole is hundreds of kilometers away from the geographic North Pole."
 
1000RR said:
A quick Google came up with the following. Reading it leads me to believe it moves in one direction.

"The magnetic North Pole is the location in the Northern Hemisphere where the planet's magnetic field lines point straight downwards, penetrating the surface of the Earth. Its location changes at a rate of about 56 kilometers (35 miles) per year. Currently located in the Arctic Ocean north of Canada, it has recently been moving towards the north coast of Russia at an increasing speed. In any case, the magnetic North Pole is hundreds of kilometers away from the geographic North Pole."
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The Poles are building up steam for an invasion of Russia!
 
Have you bought the signal inverter yet, for when the poles flip?
$2449.00 at Aircraft Spruce. Get in line!
 
The compass rose at College Park, MD was created when the Wright Brothers started their flying school for the Army. About a decade ago, the Museum on the field did an archeological project, and restored that original rose. It is more than 10 degrees from the co located modern rose. And the modern rose is about 1 degree behind already.

1906 to 2010 a a lot of years, with the pole moving that rapidly.
 
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