35 This classification is presented in Fig. 12. Operational/ Environmental Discipline- Level Uncertainty System-Level Fig. 12. Uncertainty Classification for Aircraft Systems Design. 35
11 3 rd Annual Predictive Methods Conference, Newport Beach, California, June 2003 Operational/ environmental uncertainty is concerned with modeling how a vehicle or fleet of vehicles will be utilized over its useful life. System-level uncertainty is concerned with the requirements, synthesis, and predicted performance of a vehicle. Finally, discipline-level uncertainty is concerned with the various contributing analyses that are required to synthesize vehicle alternatives. Uncertainty research in space system design is very recent. Ref. 34 defines uncertainty as “inability to quantify precisely; a distribution that reflects potential outcome”. Uncertainty is classified into development, operational, and model. 34 Fig. 13 illustrates this classification and Table 7 defines these uncertainties. Political Development Model Requirements Development cost Development schedule Development technology Uncertainty Political Lifetime Obsolescence Integration Operations cost Market Operational Development Operational Fig. 13. Uncertainty Classification for Space Architectures. 34 Table 7 Uncertainty Definitions for Space Architectures 34 Uncertainty Subclassification Uncertainty of … Development Political development funding instability Requirements requirements stability Cost developing within a given budget Schedule developing within a given schedule profile Technology technology to provide performance benefits Operational Political operational funding instability Lifetime performing to requirements in a given lifetime Obsolescence performing to evolving expectation in a given lifetime Integration operating within other necessary systems Cost meeting operations cost targets Market meeting demands of an unknown market Model n/a no formal definition This classification and associated definitions appears to build on the management classification provided by Ref. 15. Ref. 34 does not provide significant details on uncertainty types beyond these definitions and primarily concerns itself with mitigating uncertainty by portfolio management (drawing on an analogy to economics).