Acceleration error on a magnetic compass occurs when the aircraft accelerates on which headings, causing the compass card to rotate toward which direction?

• A. East or West, toward North
• B. North or South, toward East
• C. East or West, toward South
• D. North or South, toward North

Answer: (A)

Acceleration error on a magnetic compass comes from the inertia of the magnetized compass card as the airplane changes speed. When you accelerate on an east or west heading, the needle tends to lag behind the change in velocity, causing the compass card to deflect toward the geographic north. If you decelerate on those headings, the deflection reverses toward the south. On north or south headings, this acceleration-induced deflection is minimal, so the error is mainly observed on east or west headings with the card turning toward the north.