Which term is used to describe the angular difference between true north and magnetic north as depicted on a chart?

Which term is used to describe the angular difference between true north and magnetic north as depicted on a chart?

• A. Variation
• B. Deviation
• C. Declination
• D. Magnetic drift

Answer: (A)

The difference between true north and magnetic north shown on a chart is called variation. This value tells you how far magnetic north is from true north at that location, which you use to convert between true headings and magnetic headings when navigating. If the variation is east, you subtract it from a true heading to get the magnetic heading; if it's west, you add it. Deviation refers to errors in a compass caused by the vessel or aircraft itself, not the chart's depiction. Declination is a term that some contexts use for the same concept, but on many charts this angular difference is labeled as variation. Magnetic drift describes long-term changes in Earth's magnetic field, not the present chart value.

The difference between true north and magnetic north shown on a chart is called variation. This value tells you how far magnetic north is from true north at that location, which you use to convert between true headings and magnetic headings when navigating. If the variation is east, you subtract it from a true heading to get the magnetic heading; if it's west, you add it. Deviation refers to errors in a compass caused by the vessel or aircraft itself, not the chart's depiction. Declination is a term that some contexts use for the same concept, but on many charts this angular difference is labeled as variation. Magnetic drift describes long-term changes in Earth's magnetic field, not the present chart value.