The angular difference between true north and magnetic north is known as what?

• A. Deviation
• B. Variation
• C. Magnetic dip
• D. Compass error

Answer: (C)

The angular difference between true north and magnetic north is called variation, also known as magnetic declination. It varies by location and changes slowly over time as the Earth's magnetic field moves. In practice, you adjust headings by this variation when converting from true to magnetic: add the variation if it’s east, subtract it if it’s west. This correction is essential because a compass points toward magnetic north, not true north. The other terms refer to different ideas: deviation is the local interference inside the aircraft that skews the compass; magnetic dip (inclination) is the angle the magnetic field makes with the surface of the Earth; compass error is the overall error from all sources affecting a compass reading.