The Application of Magnetic Variation: Past, Present, Future (?)

Michael J. Miressi

Abstract:	When the magnetic compass was a primary--if not sole--means of navigation, the application of magnetic variation was a fairly simple process. True North and Magnetic North are not collocated; the old rhyme “East is Least and West is Best” reminded navigators to apply the correction in the proper direction. Armed with map and compass, a navigator of land, sea, or air could plot a course as a true heading, apply the local magnetic variation, and find a magnetic course to follow. The magnetic compass backed up the idea that the route he was following was the one he really wanted. The advent of radionavigation stations has done nothing to diminish the magnetic compass’ hold on navigation. Navigation stations, aligned with Magnetic North, ensure that their plotted radials coincide with those of the magnetic compass. The Magnetic North Pole is not fixed; variations for a given location constantly change. Navigators took this in stride until the recent advent of sophisticated navigation systems--many with their own magnetic variation models-produced a new problem: systems’ indications of a magnetic course often disagree with published flight data. This paper addresses the application of magnetic variation to components of the National Airspace System (NAS), discusses rates of change and differences in variation, and recommends rules for making this ancient mariners’ computation more relevant for modern navigators.
Published in:	Proceedings of the 48th Annual Meeting of The Institute of Navigation (1992) June 29 - 1, 1992 ANA Westin Hotel Dayton, OH
Pages:	91 - 96
Cite this article:	Miressi, Michael J., "The Application of Magnetic Variation: Past, Present, Future (?)," Proceedings of the 48th Annual Meeting of The Institute of Navigation (1992), Dayton, OH, June 1992, pp. 91-96.
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