What's your declination?

[Grumpy Old Man]

What's your declination? If your compass is equipped to adjust for magnetic declination (and it should be) the following link is very useful in finding the declination in your AO.

http://magnetic-declination.com/

As I have only used Brunton pocket transits for the last 40 years, I have no idea if other compasses are equipped to adjust the declination as Bruntons are, but I found the declination for my AO this morning and adjusted my compasses accordingly. Now, my compass needle, which points to magnetic north, also accurately tells me true north.

[idahobob]

I use Cammenga Tritium Lensatic Compasses, exclusively.

Started using them waaaaay back in '67 when I first went into the green machine.

And of course , you can set the declination on them.

Bob
III

[robsdak]

- 2 degrees 53 degrees W

[ak474u]

I like women, that's my declination. Oh, you mean compasses. Not sure you can set it on mine.

[bacpacker]

I am -5 degrees, 25'w.

I learned something today I wasn't aware of. Your declination can change over time. I always thought I was about -4 degrees w. Glad to know that, something else to keep track of.

Also here is another link for finding your declination.

http://www.ngdc.noaa.gov/geomag-web/

Great post Grumpy

[ak474u]

I am -5 degrees, 25'w.

I learned something today I wasn't aware of. Your declination can change over time. I always thought I was about -4 degrees w. Glad to know that, something else to keep track of.

Also here is another link for finding your declination.

http://www.ngdc.noaa.gov/geomag-web/

Great post Grumpy

I read something about older FAA maps are wrong because of declination changes at certain airports, something like if you approach by the old headings you miss the runway by 20 feet or something to that effect.

[bacpacker]

I'll have to try and find it again, but I found a site that showed locations from the 1790's with the declination and updated it every ten years. I was surprised how much it varied. My locations went from around -2 degrees to almost -6 degrees during that period.

For short distances 2 degrees won't be off that much, but for several miles is can mean a lot.

[Stormfeather]

Sounds about right. . .
Magnetic declination: -1° 30' WEST
Declination is NEGATIVE
Inclination: 71° 0'
Magnetic field strength: 55248.5 nT

[Fidel MD]

Runway numbers are based on the magnetic heading of the runway, rounded off to the nearest ten degrees. Because the magnetic variation changes a bit (usually around 10-15 seconds of arc a year) every now and then, and usually because of the rounding over rules, the numbers need to change.

So, a couple times a year in the US, runways are closed for a day or two, the numbers painted over and then repainted. This is a big hassle if there is an instrument approach, since all of the approaches, charts, etc have to be re-surveyed and reprinted.

[Stormfeather]

Thats actually interesting news Fidel, I did not know that!