Errors of magnetic compass;

Of course. A magnetic compass is a simple and reliable navigation tool, but it is subject to several predictable errors. Understanding these errors is crucial for accurate navigation, especially in aviation and maritime contexts.

Here are the primary errors of a magnetic compass, explained from the most fundamental to the more dynamic.

1. Variation (or Magnetic Declination)

This is the most fundamental error, caused by the Earth itself.

• What it is: The angular difference between True North (the geographic North Pole, the axis of Earth’s rotation) and Magnetic North (the point where the Earth’s magnetic field lines point vertically downwards). A compass needle aligns with the local magnetic field, pointing to Magnetic North.
• Cause: The Earth’s magnetic poles do not coincide with its geographic poles. Furthermore, the magnetic poles wander over time.
• Characteristics: Variation is different depending on your location on Earth. It is measured in degrees East or West.
• Correction: Variation information is printed on all aeronautical and nautical charts. Navigators must add or subtract this value to convert between True and Magnetic headings.
  • Mnemonic: “Variation East, Magnetic Least” (Magnetic heading is less than True). “Variation West, Magnetic Best” (Magnetic heading is more than True).