An aircraft instrument that provides a measure of the sideslip or yaw of the aircraft, defined as the angular measure of the relative wind in relation to a vertical plane passing through the longitudinal center of the aircraft. This device is not common to production aircraft, being found in only a few vertical takeoff and landing (VTOL) aircraft which operate in the low-speed regime. The measurement of yaw is accomplished either by a balanced vane which aligns with the wind, or through a set of pressure sensors that determine the difference in static pressure on each side of the vertical plane and hence the sideslip. The device provides equivalent information in the lateral-directional (yaw and roll) axis to the angle of attack in the longitudinal (pitch) axis.