In accelerated or decelerated flight, the magnetic compass will normally indicate correctly only when the aircraft is on which headings?

• A. North or South
• B. East or West
• C. Any heading
• D. No heading

Answer: (A)

When the aircraft accelerates or decelerates, the magnetic compass experiences an acceleration/deceleration error due to the way the needle responds to changes in movement relative to the Earth's magnetic field. This causes the compass to momentarily deflect toward the north during acceleration and toward the south during deceleration, especially noticeable on east or west headings. On a north or south heading, that error aligns with the direction you’re actually flying, so the indicated heading remains correct. For that reason, the compass is normally accurate only when the aircraft is on a north or south heading during acceleration or deceleration.