What does the term 'isogonic lines' refer to?

The term 'isogonic lines' refers to lines on a map that represent equal magnetic variation, which is the difference between magnetic north and true north at a given location. These lines are essential for navigation, as they allow aviators and mariners to adjust their compass readings to account for the local magnetic deviation caused by the Earth's magnetic field. By understanding where these lines are located and what they indicate, pilots can make more accurate navigational decisions.

In aviation, accurate navigational references are crucial for ensuring safe flight operations, and recognizing the significance of isogonic lines helps pilots correctly interpret their instruments and adjust their navigation accordingly.