The use of realistic engine usage prediction for creation of the structural design criteria for advanced propulsion systems is being encouraged by the Air Force and Navy. Inclusion of realistic structural design criteria early in the conceptual design phase will help minimize the system life cycle cost by reducing costly usage related structural deficiencies. To this end, several engine usage prediction models are currently under development by industry. Unfortunately, little continuously recorded operational engine usage data exist for the purpose of building and verifying these models. Under the Engine Usage Data Acquisition Program, the Aero Propulsion Laboratory obtained about 240 h of this type data from A-10, F-15, and F-5E aircraft during Tactical Air Force Red Flag exercises and home base training flights. A statistical and subjective analysis of these data was performed. The results show that 1) tactical aircraft engines spend a considerable amount of time in ground operation; 2) the three systems have usage containing a large number of small amplitude throttle cycles; 3) aircraft thrust to weight and mission type greatly influence mission throttle cycle content and time at temperature; 4) combat flying can be more engine damaging than peacetime training; and 5) pilot-to-pilot variation dramatically influences engine damage accumulation. The authors urge that the American engine manufacturing community enlarge the continuously recorded engine usage data base to include a broad range of aircraft and missions and to use these data to develop and validate engine usage prediction models.