I’m not sure if these examples, of the way I think of it, will help or confuse you more.
I think of True North as always being the constant, and Magnetic Variation, as always being the variable.
At LAX when heading magnetic 360 or 0 degrees you're actually heading +14 degrees from true north
Or, when you’re flying Magnetic 360 degrees you’re actually flying +14 degrees true. To fly true north (0 degrees) you must turn LEFT -14 degrees which is the variation at that location.
(Years from now it may only be 12 or 13 degrees). It varies.
The Agonic Line is an imaginary line where magnetic north and true north are the same and is located in the USA just east of Chicago as example. The Magnetic pole is true north from there in northern Canada near the Arctic Circle.
When taking flying lessons in western PA with a magnetic variation of -8.1 degrees my instructor would request me to fly true north, east, south, or west just to keep me aware of where I was really heading on the map. That was years and years ago, I'm sure it's changed by now...probably less as the magnetic pole is moving more north.
I could visualize heading to northern Canada somewhere above Chicago so I always knew that I needed to turn RIGHT to a heading plus 8 degrees from the compass.
To add to the confusion we had a compass deviation card that showed us the calibrated compass headings for every 30 degrees. It didn’t take too long to memorize that information on the card. The compass might only be accruate at two headings and vary from plus or minus a few degrees, usually not more than about 5 degrees or so.
As example, if, the card had on it for 90 degrees to steer 87 degrees then to head due east I’d need to set the compass to 87+8 or 95 degrees to head due east.
One more example: It may help you to draw a line from the magnetic north pole to LAX and then to JFK on a map. When heading 0 degrees on the compass you're following that line. Then it's easy to tell which way you need to turn to true north. From there it's the same for each heading all around the compass.
Last edited by NikeHerk67; 05-04-2012 at 05:58 AM.
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