PROBE I models an attack air force vs. an interceptor defense in a conflict extending over as many as thirty missions. For any mission, the attack sorties may be allocated to any combination of (1) aircraft with bombs only, assigned to prime targets, (2) similar aircraft targeting hostile interceptor bases, or (3) aircraft with only air-combat weapons that defend the bombers. The model shows the results of one or a series of missions in which the experimenter specifies the allocations; alternatively, it can determine, mission-by-mission, the allocations that (with the total number of missions specified) will maximize a given objective, such as "total bomb tonnage reaching prime targets." The heart of the model is a set of differential equations that represent the rates at which aircraft change from one state to another, e.g., loaded to unloaded--engaged to disengaged, etc. PROBE I is programmed for the IBM 370/158. 130 pp.