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I am studying how instrument flight procedures are coded to ARINC-424 format, and since I was curious about the method used to determine the outbound/inbound magnetic courses, I checked the section describing the magnetic variation field.

ARINC-424 Version 18, Page 75, section 5.39: […] the government authority has established the value as valid for everything associated with a given location. For example, if a Magnetic Variation of Record is established for an airport location, everything referenced to that airport will use the same value. This is of interest as it means that Terminal Procedure design is also based on that value.

Does this imply that an officially published chart will depict each leg's magnetic azimuth based on the magnetic declination value of the associated airport, rather than the magnetic declination corresponding to the first point of the particular leg of the procedure?

In other words, if I want to find the true azimuth of an aircraft's heading, while it follows a specific terminal procedure, do I substract from the magnetic azimuth depicted on chart the magnetic variation value of the associated airport?

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    $\begingroup$ The distances between the farthest point in the procedure and the airfield are small enough that there shouldn't be significant magnetic variation between the two. $\endgroup$ – GdD Jun 14 at 12:00

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