Heading (navigation)

In navigation, the heading of a vessel or aircraft is the compass direction in which the craft's bow or nose is pointed.

[a] Any difference between the heading and course is due to the motion of the underlying medium, the air or water, or other effects like skidding or slipping.

The most common use of the TVMDC method is deriving compass courses during nautical navigation from maps.

The Magnetic North Pole is currently in Northern Canada and is moving generally south.

In the year 1900, the agonic line passed roughly through Detroit and then was east of Florida.

It currently passes roughly west of Chicago, IL, and through New Orleans, LA.

The local magnetic variation is indicated on NOAA nautical charts at the center of the compass rose.

The magnitude of the compass deviation varies greatly depending upon the local anomalies created by the vessel.

Electrical wires carrying current have a small magnetic field around them and can cause deviation.

Any type of magnet, such as found in a speaker can also cause large magnitudes of compass deviation.

Some use the mnemonic: True Virgins Make Dull Companions - Going downward Add Whiskey (or West).

Easy way to calculate compass magnetic or true north is maintaining the original signs for variation and deviation (+ for east and -for west): C+(Var)= M+(Dev)= T / T-(Dev)= M-(Var)= C

This wind triangle shows a jet airliner 's heading towards point B (HDG, in black; TAS=True Air Speed) and its course towards C (TR, track, in blue; GS=Ground Speed). The drift angle (shaded red) is due to the wind velocity (W/V, in green).
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.