STPA-based hazard analysis of a complex UAV system in take-off

The ATRC-UAV system is a multifunction system with close subsystem component interactions. Considering its complexity, component hardware failures are no longer the only reason for flight testing accidents, and a comprehensive approach is needed for hazard analysis. Systems-Theoretic Process Analysis (STPA) is a novel technique based on systems theory rather than traditional reliability theories. It addresses safety of complex systems as a control problem rather than a failure problem. In this paper, we adopt STPA on a subscale Unmanned Aerial Vehicle (UAV) system take-off hazard analysis and the potential feasibility of STPA for complex UAV system is demonstrated. Unsafe control actions during take-off and their relevant control flaws are identified and safety constrains at different levels are specified. In addition to component failures, we discover that component interactions and flawed human decision making might also lead to violation of safety constrains by using STPA.