Which of the arrows in the magnetic variation symbol represents which North value (Magnetic N, True N)? According to my calculations, the arrow pointing to the top should point to magnetic north, perpendicular to the page. But I am not sure.
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2$\begingroup$ Related: Are Jeppesen Approach, SID charts in Magnetic North or True North? $\endgroup$– BianfableFeb 10 at 7:10
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2$\begingroup$ You say "according to my calculations" - what calculations did you make? As it stands the question is essentially a duplicate of the link @Bianfable posted, but if you explain your thinking you might get a more interesting answer tailored to your understanding. $\endgroup$– TypeIAFeb 10 at 7:40
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$\begingroup$ To find magnetic north, variation is added or subtracted from true north. If the variation is eastward, you subtract the variation from true north to find magnetic north. But if the variation is west, you add variation to true north to get magnetic north... $\endgroup$– pilot162Feb 10 at 9:01
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$\begingroup$ ...If the variation is west, the direction of increase will always be clockwise on the 360-degree dial, so the true north arrow will be to the left of the magnetic north arrow. But if the variation is east, the direction of decrease will always be counterclockwise on the 360-degree dial, so the true north arrow will stay to the right of the magnetic north arrow. I hope you have the ability to perceive what I mean. $\endgroup$– pilot162Feb 10 at 9:01
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1 Answer
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The chart is always drawn with true north pointing straight up. The magnetic variation is given on the arrow pointing along the local direction of the field lines (not technically towards magnetic north). So 10°W means the local field lines are 10° to the West of true north.
You said in the comments
To find magnetic north, variation is added or subtracted from true north. If the variation is eastward, you subtract the variation from true north to find magnetic north. But if the variation is west, you add variation to true north to get magnetic north.
This is not quite correct. This rule applies to a heading or course, not the direction of true/magnetic north. Consider this picture:
We have 10°W variation, so we have to add the variation to the true heading to get the magnetic heading:
$$ \color{green}{\text{true heading}} + \text{variation} = \color{red}{\text{magnetic heading}} $$
$$ \color{green}{30^\circ} + 10^\circ = \color{red}{40^\circ} $$
Therefore, your pictures are perfectly consistent with this rule (if applied to a heading or course).
