What does magnetic deviation refer to?

Magnetic deviation refers specifically to the phenomenon where the compass needle is deflected from true magnetic north due to the magnetic influences of the aircraft itself. This can occur due to metal structures, electrical equipment, and other magnetic fields present within the aircraft. Because the compass relies on the Earth's magnetic field to indicate direction, any internal magnetic components can cause inaccuracies in the compass reading, which is critical for navigation.

Understanding magnetic deviation is particularly important for pilots, as they need to calibrate their compass to account for this deviation and ensure accurate navigation. This is usually assessed during pre-flight checks to enhance safety and operational effectiveness.