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# Compass Deviation & Errors

## Magnetic Dip

The magnet suspended in our compass aligns with Earth’s magnetic field. However, as we move away from the equator, the magnetic field is not parallel to the Earth’s surface. This causes the magnet to ‘dip’ towards the pole.

At the equator, magnetic dip is 0°
At the poles, magnetic dip is 90°

This means that at latitudes greater than 60° North or 60° South the magnetic compass is less accurate.

## Dip Angle

The magnetic force (from the Earth’s magnetic field) that the magnet aligns itself to is known as the Total Magnetic Force (T). This can be divided into the Horizontal Component (H) and the Vertical Component (V).

The Dip Angle is the angle between the Horizontal Component (H) and the Total Magnetic Force (T).

In other words, the dip angle is how far ‘down’ the magnet has dipped from horizontal.

As latitude increases, the Horizontal Component (H) decreases, the Vertical Component (V) increases and Dip Angle increases.

## Compass Errors

Some aircraft components create their own, weaker magnetic fields which interfere with the ability of the compass to align with the Earth’s magnetic field. This causes slight errors in the compass. Components that create their own magnetic fields include:

Aircraft electrical systems
Aircraft metal components