Which of the following best describes 'Compass Deviation'?

Compass deviation refers to the error in a magnetic compass caused by local magnetic influences within the vessel or aircraft itself. Unlike magnetic variation, which occurs due to the difference between true north and magnetic north based on geographic location, deviation is specifically related to magnetic fields generated by electronic equipment, metal structures, or even the magnetic properties of the craft itself.

When a compass is affected by these local magnetic influences, it may show readings that deviate from true magnetic north, leading to errors in navigation. Understanding and correcting for this deviation is crucial for accurate navigation, particularly in confined environments such as in aircraft or ships.

The other options do not accurately capture the concept:

• Consistent readings in a magnetic compass suggest a stable environment free from interference, which is not the hallmark of deviation.

• Variation due to atmospheric conditions relates more to changes in magnetic field strength and direction that are external, rather than local interference.

• A fault in navigational equipment could lead to a range of navigation errors, but it does not specifically define the phenomenon of compass deviation, which is fundamentally about local magnetic influence rather than a broader equipment failure.