{"id":14210,"date":"2025-06-03T16:11:13","date_gmt":"2025-06-03T10:41:13","guid":{"rendered":"https:\/\/ibexaviation.com\/pilot-training\/?p=14210"},"modified":"2026-07-26T10:10:27","modified_gmt":"2026-07-26T04:40:27","slug":"magmetism-compass","status":"publish","type":"post","link":"https:\/\/ibexaviation.com\/pilot-training\/magmetism-compass\/","title":{"rendered":"Magnetism and Compass"},"content":{"rendered":"<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/general-navigation\/g5-earth-magnetism-1.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<h2>Earth Magnetism<\/h2>\n<p>Earth Magnetism is the Earth&#8217;s natural magnetic field, which acts like a giant magnet with magnetic north and south poles. It allows magnetic compasses to indicate direction for aircraft navigation. Pilots use Earth&#8217;s magnetic field to maintain the correct heading during flight.<\/p>\n<h3>Earth Magnetic Field<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/general-navigation\/g5-earth-magnetism-2.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>The Earth behaves like a giant magnet with a Magnetic North Pole and a Magnetic South Pole.<\/li>\n<li>The Earth&#8217;s magnetic field is not exactly aligned with its rotational (polar) axis.<\/li>\n<li>Magnetic North is not co-located with True North.<\/li>\n<li>Magnetic North is approximately <strong>400 NM<\/strong> away from True North.<\/li>\n<li>Magnetic North drifts at approximately <strong>22 NM per year<\/strong>.<\/li>\n<li>The Magnetic North and South Poles are not diametrically opposite each other.<\/li>\n<\/ul>\n<h3>Magnetic Compass<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/general-navigation\/g5-earth-magnetism-3.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>The magnetic compass is the primary direction-finding instrument in an aircraft.<\/li>\n<li>It uses only the <strong>north-seeking end<\/strong> of the magnet for direction indication.<\/li>\n<li>The magnetic south-seeking end plays no role in direction finding.<\/li>\n<\/ul>\n<h3>Magnetic Variation<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/general-navigation\/g5-earth-magnetism-4.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Variation is the angular difference between <strong>True North<\/strong> and <strong>Magnetic North<\/strong>.<\/li>\n<li>Variation is measured in degrees.<\/li>\n<li>It is expressed as Magnetic North being <strong>East<\/strong> or <strong>West<\/strong> of True North.<\/li>\n<li>Variation depends on the aircraft&#8217;s position relative to the Magnetic North Pole.<\/li>\n<li>The maximum possible variation is <strong>180&deg; East<\/strong> or <strong>180&deg; West<\/strong>.<\/li>\n<\/ul>\n<h3>Isogonal and Agonal Lines<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/general-navigation\/g5-earth-magnetism-5.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li><strong>Isogonals<\/strong> are lines joining places of equal magnetic variation.<\/li>\n<li>Isogonal lines converge toward the True and Magnetic Poles.<\/li>\n<li><strong>Agonal lines<\/strong> join places where the magnetic variation is zero.<\/li>\n<li>An agonal line is approximately a great circle connecting the True and Magnetic North Poles.<\/li>\n<\/ul>\n<h3>Calculation of Magnetic Variation<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/general-navigation\/g5-earth-magnetism-6.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Variation is applied to Magnetic Heading to obtain True Heading.<\/li>\n<li>West variation is considered <strong>negative (-)<\/strong>.<\/li>\n<li>East variation is considered <strong>positive (+)<\/strong>.<\/li>\n<li>Magnetic direction can be calculated using the local variation.<\/li>\n<li><strong>Variation West (-): Magnetic Best<\/strong> (subtract variation).<\/li>\n<li><strong>Variation East (+): Magnetic Least<\/strong> (add variation).<\/li>\n<\/ul>\n<h3>Magnetic Dip Angle<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/general-navigation\/g5-earth-magnetism-7.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>The Earth&#8217;s magnetic field can be resolved into horizontal and vertical components.<\/li>\n<li>The horizontal component provides the directive force for the magnetic compass.<\/li>\n<li>Magnetic dip is the angle between the Earth&#8217;s magnetic field and the horizontal plane.<\/li>\n<li>The dip angle is <strong>0&deg;<\/strong> at the Magnetic Equator, where a freely suspended magnet remains horizontal.<\/li>\n<li>The dip angle is <strong>90&deg;<\/strong> at the Magnetic Poles, where the magnet becomes vertical.<\/li>\n<\/ul>\n<h3>Lines of Inclination<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/general-navigation\/g5-earth-magnetism-8.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Lines of inclination join places having equal magnetic dip.<\/li>\n<li>An <strong>Aclinic Line<\/strong> joins places where the magnetic dip angle is zero.<\/li>\n<li>The Aclinic Line coincides with the Magnetic Equator.<\/li>\n<li>Magnetic field strength is measured in <strong>microtesla (&micro;T)<\/strong>.<\/li>\n<li>A magnetic compass requires a minimum field strength of <strong>6 &micro;T<\/strong> to function properly.<\/li>\n<\/ul>\n<h3>Compass Deviation<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/general-navigation\/g5-earth-magnetism-9.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Electrical equipment and metallic objects near the aircraft compass produce <strong>compass deviation<\/strong>.<\/li>\n<li>Compass deviation is the angular difference between <strong>Magnetic North<\/strong> and <strong>Compass North<\/strong>.<\/li>\n<li>Deviation is measured in degrees.<\/li>\n<li>It is expressed as Compass North being East or West of Magnetic North.<\/li>\n<li>A <strong>Compass Swing<\/strong> is performed to prepare a compass deviation card.<\/li>\n<\/ul>\n<h3>Calculation of Compass Deviation<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/general-navigation\/g5-earth-magnetism-10.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Deviation is applied to Compass Heading to obtain Magnetic Heading.<\/li>\n<li>Compass direction can be calculated using magnetic direction and deviation.<\/li>\n<li><strong>Deviation West (-): Compass Best<\/strong> (subtract deviation).<\/li>\n<li><strong>Deviation East (+): Compass Least<\/strong> (add deviation).<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Earth Magnetism Earth Magnetism is the Earth&#8217;s natural magnetic field, which acts like a giant magnet with magnetic north and south poles. It allows magnetic compasses to indicate direction for aircraft navigation. Pilots use Earth&#8217;s magnetic field to maintain the correct heading during flight. Earth Magnetic Field The Earth behaves like a giant magnet with a Magnetic North Pole and a Magnetic South Pole. The Earth&#8217;s magnetic field is not exactly aligned with its rotational (polar) axis. Magnetic North is not co-located with True North. Magnetic North is approximately 400&hellip;<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"disable_featured_image":false,"footnotes":""},"categories":[324],"tags":[],"class_list":["post-14210","post","type-post","status-publish","format-standard","hentry","category-cpl-atpl-general-navigation"],"_links":{"self":[{"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/posts\/14210","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/comments?post=14210"}],"version-history":[{"count":1,"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/posts\/14210\/revisions"}],"predecessor-version":[{"id":16622,"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/posts\/14210\/revisions\/16622"}],"wp:attachment":[{"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/media?parent=14210"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/categories?post=14210"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/tags?post=14210"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}