What term is used to describe the compass error caused by the aircraft's own magnetic fields and electrical systems?

• A. Magnetic deviation
• B. Magnetic variation
• C. Magnetic inclination
• D. Magnetic resonance

Answer: (A)

Magnetic deviation is the compass error caused by the aircraft’s own magnetic fields and electrical systems. The airplane’s metal structure, engines, wiring, and onboard equipment create local magnetic fields that distort the reading the compass shows, so the indicated heading can be offset from the true magnetic direction. Pilots counter this by using a deviation card specific to the aircraft to apply the proper corrections for each heading. This is different from magnetic variation, which is the difference between true north and magnetic north at a location, and from magnetic inclination, which is the tilt of Earth’s magnetic field; magnetic resonance isn’t a factor in standard aviation navigation.