Course (navigation)

In navigation, an object's course is the direction over the ground along which the object is currently moving.

The line connecting the object's consecutive positions on the ground is referred to as the ground track. The track the object 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 object is pointing, its orientation.

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° . 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.

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