Magnetic Dip is the tendency of a magnet to align with the Earth's magnetic field lines, causing the north end of a compass needle to dip down in the Northern Hemisphere (positive dip) and up in the Southern Hemisphere (negative dip). The magnetic compass will tend to dip more at the poles than closer to the magnetic equator.

Magnetic Dip: Turning Errors

A turning error that can take place involves a turn from a Northerly heading, during that time the compass will briefly indicate a turn in the opposite direction. The other turning error can take place when turning from a Southerly heading, which will cause the compass to indicate a turn in the correct direction, but this will occur at a faster rate.

Remember UNOS (northern hemisphere):

• Undershoot North

• Overshoot South

The aircraft’s hedging is 270° and the shortest way to a heading 360° is a right turn.

When an aircraft turns from Southerly headings to Northerly headings causes the compass to indicate a turn in the correct direction, but this will occur at a faster rate. So in this example the turn must be terminated sooner (about 30°), before heading reaches 360°. The turn must be terminated at 330°.

The indication of the magnetic compass should the turn be terminated is 330°