Three-figure bearings

Suppose you were in the middle of nowhere, and there were no signs or landmarks to help you find your way.

Would you know how to find your way home?

Someone might tell you via phone or radio to 'walk to your left', or 'turn through \({60}^\circ\) and then start walking', but how would they know which way you were pointing in the first place?

One way of describing direction from a point is to use three-figure bearings.

Compass

A compass always points north. Bearings are measured from the north line, always in a clockwise direction.

So when someone tells you to walk on a bearing of \({120}^\circ\), you should face north, turn clockwise through \({120}^\circ\) and start walking.

Key fact

Bearings are always described using three figures.

So for less than 100° put an appropriate number of 0s in front, eg 020°, 037°, 002°, 007°.

Example

An aeroplane takes off from Belfast International airport, as shown in the diagram below.

The angle between the north line and the flight path of the aeroplane is \({30}^\circ\).

So we can say that the aeroplane is flying on a bearing of \({030}^\circ\) from Belfast International airport.

Example

A ship sails from a harbour H to a port P, as shown in the diagram.

A ship sails from a harbour H to a port P, as shown in this diagram.

To calculate the bearing subtract \(50^\circ\) from \(360^\circ\) to find the reflex angle (labelled H) as bearings must be given in a clockwise direction from north.

The direction the ship sailed can be given as a bearing of \(310^\circ\).