A description of the capabilities of SAMSOM II, RAND's operations model for the simulation of aircraft operations and logistics support problems. The manual provides information on input requirements, model logic, and operating instructions; it also describes model outputs and includes a sample simulation to familiarize the user with model operational details. Although designed primarily to simulate typical Air Force operations, SAMSOM II may be used to examine the operational capabilities of other organizations or combinations of aircraft and logistics support elements. The model also simulates operations for one or more weapon systems at one or more bases involving multiple resource allocations and operational requirements. SAMSOM II should prove useful to analysts and managers responsible for monitoring weapon system developments, estimating operations capabilities, and determining logistics support requirements.