What compass error occurs during deceleration on an easterly heading?

When a helicopter is decelerating on an easterly heading, the compass experiences a specific phenomenon known as magnetic dip, which results in a compass error. During deceleration on an easterly heading, the compass will show a turn toward the south. This occurs because of the dynamics of magnetic fields and the inertia of the compass needle.

As the helicopter slows down, the inertia causes the compass to lag behind the actual heading, causing it to indicate a position slightly to the south. This effect is more pronounced with rapid or substantial changes in speed. Recognizing this behavior is crucial for pilots, as it can lead to navigational inaccuracies if not properly understood or accounted for.

Understanding how the compass behaves during changes in speed and direction helps pilots maintain accurate situational awareness and make informed navigational decisions.