Course, track, route and heading
edit
True heading (left) and magnetic heading (right)
Heading and track (A to B)
1 – True North
2 – Heading, the direction the vessel is "pointing towards"
3 – Magnetic north, which differs from true north by the magnetic variation.
4 – Compass north, including a two-part error; the magnetic variation (6) and the ship's own magnetic field (5)
5 – Magnetic deviation, caused by vessel's magnetic field.
6 – Magnetic variation, caused by variations in Earth's magnetic field.
7 – Compass heading or compass course, before correction for magnetic deviation or magnetic variation.
8 – Magnetic heading, the compass heading corrected for magnetic deviation but not magnetic variation; thus, the heading reliative to magnetic north.
9, 10 – Effects of crosswind and tidal current, causing the vessel's track to differ from its heading.
A, B – Vessel's track.
The path that a vessel follows over the ground is called a ground track, course made good or course over the ground.[1] For an aircraft it is simply its track.[3] The intended track is a route. For ships and aircraft, routes are typically straight-line segments between waypoints. A navigator determines the bearing (the compass direction from the craft's current position) of the next waypoint. Because water currents or wind can cause a craft to drift off course, a navigator sets a course to steer that compensates for drift. The helmsman or pilot points the craft on a heading that corresponds to the course to steer. If the predicted drift is correct, then the craft's track will correspond to the planned course to the next waypoint.[1][3] Course directions are specified in degrees from north, either true or magnetic. In aviation, north is usually expressed as 360°.[4] Navigators used ordinal directions, instead of compass degrees, e.g. "northeast" instead of 45° until the mid-20th century when the use of degrees became prevalent.[5]
- ^ a b c
Bartlett, Tim (2008), Adlard Coles Book of Navigations, Adlard Coles, p. 176, ISBN 978-0713689396
- ^
Husick, Charles B. (2009). Chapman Piloting, Seamanship and Small Boat Handling. Sterling Publishing Company, Inc. p. 927. ISBN 9781588167446.
- ^ a b c Federal Aviation Administration (FAA) (2016-09-25). Pilot's Handbook of Aeronautical Knowledge: FAA-H-8083-25B. Ravenio Books.
- ^ Michael Nolan (2010). Fundamentals of Air Traffic Control. Cengage Learning. p. 201. ISBN 978-1-4354-8272-2.
For example, a runway heading north would have a magnetic heading of 360°.
- ^ Rousmaniere, John; Smith, Mark (1999). The Annapolis Book of Seamanship: Third Edition: Completely Revised, Expanded and Updated. Simon and Schuster. p. 234. ISBN 9780684854205.