The Fighter Mafia was a controversial group of U.S. Air Force officers and civilian defense analysts who, in the 1970s, advocated the use of John Boyd and Thomas P. Christie's Energy-Maneuverability (E-M) theory as the sole driver in designing fighter aircraft. The mathematical model developed enabled quantitative (number-driven) one-to-one comparison of the performance of aircraft in terms of air combat maneuvering, independent of real world flight testing. The model was used to identify deficiencies with both designs in service and proposed designs of the time. The Fighter Mafia would influence the specifications of the F-X, and went on to independently develop specifications for the Light Weight Fighter. The group was instrumental in a return to air-combat maneuverability as one of the