In the Northern Hemisphere, the magnetic compass will normally indicate a turn toward the south when the aircraft is decelerated on which heading?

• A. West heading
• B. East heading
• C. North heading
• D. South heading

Answer: (A)

Acceleration/deceleration error on a magnetic compass in the Northern Hemisphere is being tested here. When you speed up, the compass tends to indicate turning toward the north; when you slow down, it tends to indicate turning toward the south. This stems from how the suspended magnetic needle reacts to longitudinal acceleration in the Earth’s magnetic field.

On a west heading, decelerating produces the classic south indication because the combination of backward acceleration along your path and the horizontal magnetic field components causes the needle to deflect toward the south, making the compass appear to turn in that direction. This heading-specific behavior is why the west heading is the scenario described by the question.