Which term describes the angular difference between true north and magnetic north on navigation charts?

Which term describes the angular difference between true north and magnetic north on navigation charts?

• A. Variation
• B. Deviation
• C. Magnetic Declination
• D. True North

Answer: (A)

Magnetic variation is the angular difference between true north (geographic north) and magnetic north as shown on navigation charts. This value lets pilots convert between true headings, which are based on geographic north, and magnetic headings, which the compass indicates. For example, if the chart shows variation to the west, a true heading of 90 degrees would correspond to a magnetic heading of 78 degrees (you subtract the variation). If the variation is to the east, you would add it to the true heading to get the magnetic heading. Variation changes with location and over time as Earth's magnetic field evolves, so charts display the current variation for the area. Deviation refers to errors caused by the aircraft itself, not the chart, and magnetic declination is a broader term sometimes used in other fields, but on navigation charts the offset between true north and magnetic north is labeled as variation.

Magnetic variation is the angular difference between true north (geographic north) and magnetic north as shown on navigation charts. This value lets pilots convert between true headings, which are based on geographic north, and magnetic headings, which the compass indicates. For example, if the chart shows variation to the west, a true heading of 90 degrees would correspond to a magnetic heading of 78 degrees (you subtract the variation). If the variation is to the east, you would add it to the true heading to get the magnetic heading. Variation changes with location and over time as Earth's magnetic field evolves, so charts display the current variation for the area. Deviation refers to errors caused by the aircraft itself, not the chart, and magnetic declination is a broader term sometimes used in other fields, but on navigation charts the offset between true north and magnetic north is labeled as variation.