What is the significance of magnetic variation?

The significance of magnetic variation lies in its role in navigation, specifically how it relates to the difference between magnetic north and true north. This difference is crucial for pilots as they rely on aircraft compasses, which point toward magnetic north, while maps and navigational charts are typically oriented to true north. Understanding magnetic variation allows pilots to adjust their headings appropriately, ensuring accurate navigation and preventing errors due to this discrepancy.

The other options reference aspects of flying that do not pertain to magnetic variation. Airspeed definitions, altitude readings, and fuel calculations are determined by various factors like aircraft performance, pressure settings, and weight, rather than the relationship between magnetic and true north.