What should the Ball indicate in the Turn Coordinator during an Instrument Check when moving?

In a properly coordinated turn, the ball in the Turn Coordinator should indicate opposite the direction of the turn. This behavior is a demonstration of the principles of flight dynamics, specifically how the forces act on an aircraft during a turn.

When an aircraft enters a banked turn, the centrifugal force acting on the aircraft results in a component of the lift vector acting outward from the turn, which can cause the aircraft to skid or slip if not properly managed. The Turn Coordinator aids in visualizing this, as the ball shows the relationship between the aircraft's coordination and the actual turn.

If the aircraft is making a turn and the ball is on the side opposite to the direction of the turn, this indicates that the aircraft is effectively managing its balance—meaning that the bank angle is appropriate for the rate of turn. Conversely, if the ball is on the same side as the turn, it suggests a skid, while a centered ball indicates a steady, balanced flight with no rotation being applied.

Therefore, for correct coordination during an Instrument Check, the ball's behavior providing information about the state of the turn can be crucial to safely piloting the aircraft.