In aviation, the turn and bank indicator shows both the rate of turn and the coordination of the turn. The rate of turn is indicated gyroscopically and the coordination of the turn is shown by a inclinometer, which works in a way similar to a simple pendulum. No pitch information is provided.
The rate of turn is the actual rate at which the airplane is rotating. Tick marks generally show a 'standard rate turn' (3 degrees per second). The indicator is a white vertical needle. There are white markings at top center (for zero rate of turn), and one on each side, representing standard rate of turn to the left and right, respectively.
The coordination of the turn indicates whether the airplane is banked appropriately for its rate of turn. In an uncoordinated turn, the plane either slips or skids. In a properly coordinated turn, a passenger asked to point straight down would always point in the same direction relative to the airplane, straight into his seat, regardless of the actual bank angle of the plane.
The turn and bank indicator has been largely replaced by the newer turn coordinator. The turn and bank instrument is usually seen only on aircraft manufactured prior to about 1970.