What does the turn coordinator indicate regarding the bank attitude of the aircraft?

The turn coordinator provides an indirect indication of the bank attitude of the aircraft by showing the rate of turn and the coordination of that turn. While it does not display the bank angle directly, it helps pilots gauge whether the aircraft is in a coordinated turn or if it is skidding or slipping.

When an aircraft is in a standard rate turn (which is roughly three degrees per second), the turn coordinator’s miniature airplane symbol will align with the horizon bar, indicating that the bank is appropriate for that rate of turn. Pilots can use this information to adjust the bank angle and ensure it is neither excessive nor inadequate, thus indirectly assessing the bank attitude necessary for the type of turn intended. This is why it is essential for maintaining control and ensuring the safety of flight maneuvers, particularly in instrument flying conditions.