What is deviation in the context of aircraft navigation?

Deviation in the context of aircraft navigation refers to magnetic interference that affects the compass readings within the aircraft. Specifically, it is caused by magnetic fields from electronic equipment and metal structures inside the aircraft, which distort the magnetic compass's ability to provide an accurate heading.

This magnetic interference can lead to discrepancies between the actual heading of the aircraft and what the compass indicates, necessitating periodic calibration to account for these variations. It’s essential for pilots to understand and compensate for deviation, particularly in navigating and utilizing their compasses effectively during flight.

While other options such as magnetic interference from nearby objects or compass calibration issues may initially seem relevant, they do not specifically address the internal magnetic influences that are classified as deviation. Weather-related navigation errors also fall outside the definition, which is strictly focused on issues arising from the aircraft's internal environment.