On September 24, 1929, then-Lieutenant (later General) James H. "Jimmy" Doolittle, U.S. Army, demonstrated the first "blind" flight, performed exclusively by reference to instruments and without outside visibility, and proved that instrument flying was feasible.[8][9] Doolittle used newly developed gyroscopic instruments—attitude indicator and gyrocompass—to help him maintain his aircraft's attitude and heading, and a specially designed directional radio system to navigate to and from the airport.[10][note 1] Doolittle's experimental equipment was purpose-built for his demonstration flights; for instrument flying to become practical, the technology had to be reliable, mass-produced and widely deployed, both on the ground and in the aircraft fleet.[4]