Turn indicator is an instrument measuring an angular velocity within ±3°/s of aircraft vertical axis which corresponds to parameters of the turn performed at speed of 350 km/h at the bank of 45°. Turn indicator incorporates a liquid level indicating a slip during turn. Reaching of gyro’s operating speed is indicated by covering of OFF sign at turn indicator dial. The deflection greater than corresponding to an angular velocity of ±4°/s is limited by a dead stop.