The angular difference between true north and magnetic north is called?

The angular difference between true north and magnetic north is known as variation. This term refers to the discrepancy that exists due to the Earth's magnetic field, which is not aligned perfectly with the geographic poles. Variation is commonly measured in degrees and can change based on geographic location, reflecting how magnetic compasses may not point directly toward true north, hence requiring adjustments for navigation.

Understanding variation is crucial for pilots and navigators, as it allows them to compensate for this difference when plotting courses and navigating, ensuring accuracy in their direction-finding efforts. This understanding is fundamental to safe and effective navigation in both aviation and maritime operations.