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In navigation, a vehicle's course is the direction over the ground the vehicle is currently moving in. == Course, track, route and heading == The line connecting the vehicle's consecutive positions on the ground is referred to as the ground track. The ''track'' the vehicle was intended to follow is called the route. For ships and aircraft, the ''route'' is represented by the great circle line that connects the previous waypoint with the next waypoint. The responsibility of a navigator is to make the ''track'' coincide as much as possible with the ''route''. The direction of the ''route'' is called the route course. "Course" exceptionally, and arguably erroneously, may also refer to the ''route'', such as in a course deviation indicator, in which case it no longer constitutes an angle but rather a line. The direction of the great circle line that runs from the current position to the next waypoint is called the course to steer, or the bearing to that waypoint. The tracking angle is the angle between the ''course to steer'' and the ''course''. The heading is the direction to which the "nose" of the vehicle is pointing. Directions (''course to steer'', ''course'', ''heading'' and ''route course'') are typically measured clockwise from north, either true or magnetic, in degrees from 0° to 359°, following compass convention (0° being north, 90° being east, etc.). In aviation, north is usually expressed as 360° instead of 0° 〔(【引用サイトリンク】url=http://www.airliners.net/aviation-forums/tech_ops/read.main/144883/ )〕 . For land based vehicles (like cars) ''heading'' and ''course'' are typically identical, but for aircraft the action of wind, and for vessels the actions of wind and current may cause the two to differ significantly. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Course (navigation)」の詳細全文を読む スポンサード リンク
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