What happens to the compass card during acceleration when flying on an easterly heading?

When flying on an easterly heading and the helicopter accelerates, the compass card will exhibit a behavior known as "variation" due to the Earth's magnetic field dynamics. During acceleration, especially on an easterly heading, the magnetic compass tends to lag behind the actual heading. This occurs because the acceleration induces a false heading indication where the compass card appears to rotate toward North.

The reason this happens is due to the inertia of the compass fluid and the magnet's response to changes in movement. When you accelerate to the east, the compass experiences a shift that reflects an apparent heading to the North for a brief moment before it stabilizes again, creating confusion about the actual heading for pilots. Understanding this behavior is crucial for effective navigation and awareness of potential heading errors during operations.