Complexities of system of systems operational availability modeling

Calculating operational availability (A_o) for a system of systems (SoS) presents unique challenges to reliability, availability, and maintainability (RAM) assessment, modeling, and analysis. System interdependencies and complex interrelated sustainment operations that exist in a SoS present complexities that must be accounted for in calculating or estimating A_o for the SoS. These system interdependencies affect the operating, operable, and down times of the individual systems. Both system-level and SoS-level A_o performance must be assessed within the SoS context for logistics and planning purposes. However, metrics calculated for the individual systems as part of the SoS may not be appropriate for assessing the individual system performance against their individual system requirements. In most cases, simulation modeling is required to capture the complex operating, operable, and down time hours of a SoS and the systems in the SoS, and to accurately aggregate the individual system availabilities to higher SoS levels. This paper explores some of the complexities involved in SoS A_o modeling and presents So S simulation results from a modeled SoS application.