What is the main difference between magnetic variation and magnetic deviation?

The main difference between magnetic variation and magnetic deviation lies in their definitions and effects on navigation. Magnetic variation is the angular difference between magnetic north, which is the direction a magnetic compass points, and true north, which represents the geographic north pole. This difference varies depending not only on geographical location but also changes over time due to the movement of the Earth's magnetic fields.

On the other hand, magnetic deviation refers to errors in compass readings caused by magnetic interference from the materials and systems within the aircraft itself, such as electronic equipment or metal structures. Deviation can change based on the aircraft's orientation and the specific magnetic environment created by the cockpit instruments and equipment.

Understanding this distinction is critical for pilots and navigators as they rely on accurate compass readings to ensure they are on the correct course. Thus, the correct answer highlights that variation is the difference between magnetic and true north, while deviation is about the magnetic interference specific to an aircraft’s environment.