A Rotary Air-data System (RADS) periodically samples pressure data from a main rotor blade mounted pitot-scoop integrated with a high accuracy pressure sensor to compute a velocity vector that is resolvable into the aircraft's coordinate system. Mathematical techniques are employed which provide accurate computations of static pressure without a static pressure sensor. The RADS also computes the direction of the relative wind which is particularly useful when the pilot executes hover or low speed, low altitude maneuvers in restricted visibility. The availability of relative wind velocity information coupled with navigation data enhances the ability of rotary aircraft to perform accurate low altitude hover, fire control and other autopilot maneuvers.