A new approach has been developed for measuring advances in jet fighter air vehicle performance. The approach recognizes the multiparameter trade-offs imposed by the development process by simultaneously considering trends in a number of performance areas, rather than treating each area separately. Relationships are established between the time of appearance of an aircraft design and such parameters as specific power, sustained load factor, Breguet range, and payload fraction. This approach was used to project where the current acquisition environment is leading us with respect to fighter performance and suggests that (1) U.S. fighter air vehicle performance is advancing at a diminishing rate, (2) increasing the rate of advance may be costly, and (3) performance growth opportunities offered by derivative aircraft seem limited. The results raise some questions about the most desirable mix of investment in air vehicle, avionics, and armament technology.