Characterisation of Systems of Systems Failures

摘要

Systems of Systems (SoS) are systems in which the components are systems in their own right, designed separatelyand capable of independent action, yet working together to achieve shared goals. SoS are increasingly commonplace,for example Controlled Airspace and Network Centric Warfare.The increasing role of such systems in safety-critical applications establishes the need for methods to analyse andjustify their safety. However, the essential characteristics of SoS present serious difficulties for traditional hazardanalysis techniques. Operational independence, heterogenous composition, emergent behaviour and the desire fordynamic reconfiguration make conventional hazard analysis impractical. For example, it is simply not possibleto exhaustively enumerate all of the possible interactions that might take place in an SoS of any considerablecomplexity.Through systematic consideration of the characteristics of SoS, this paper classifies the types of failures associatedwith these systems. For example, the fact that components have some level of autonomy carries with it potentialhazards arising from conflicts of responsibility.Understanding of the failure modes of SoS can serve as a basis for improved identification and understanding ofSoS hazards. Through means of an example-the shooting down of Black Hawk helicopters by friendly fire duringOperation Provide Comfort - this paper illustrates how these failure modes can be seen to be key contributors inhistorical SoS accidents.