Complex availability problems solved with simulation

System owners and operators are increasingly emphasizing the actual amount of time equipment is capable of performing its intended function. For military systems, added complexity, longer service life requirements, reduced periodic maintenance, and less frequent checkouts are increasing system availability requirements. However, these factors compound the difficulty in estimating the system's true availability. With dormant or semi-dormant systems, the amount of time a system appears'' available may differ form the real'' availability. The difference in real'' and apparent'' availability is often the result of a transition from an operational but dormant state to an inoperational but dormant state. The major contributions from this research are: the development of the concept of complex'' availability that applies to systems which combine two or more elements of instantaneous, mission system, or steady-state availability; and the development of modeling technique to estimate the real'' availability for a system which involves complex'' availability. 28 refs., 2 figs