System-Theoretic Requirements Definition for Human Interactions on Future Rotary-Wing Aircraft
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Abstract
Future rotary-wing aircraft designs are highly complex, optionally manned, and include advanced teaming concepts that create unknown human-automation interaction safety risks. System-Theoretic Process Analysis (STPA) enables analysis of hazards on these complex systems. This paper demonstrates how to apply STPA in future helicopters' early concept development to prevent unacceptable losses. The system is modeled as a hierarchical control structure to capture interactions between components, including human and software controllers. Unsafe control actions are identified from these relationships and are used to systematically derive causal scenarios that arise from both hazardous interactions between system components and component failures. System requirements are then generated to mitigate these scenarios. A subset of the scenarios and requirements that address human factors related concerns are highlighted. Early identification of these problems helps designers (1) refine the concept of operations and control responsibilities and (2) effectively design safety into the system.