Rotary Unmanned Air Vehicle (UAV) is expected to enable on-demand and highly automated air transportation services over metropolitan areas. However, safety is the biggest concerns for operating rotary UAV because it flies over people and significant infrastructure. Therefore, safety risk analysis for rotary UAV operation is an essential step for operation validation. Rotary UAV safety risk can be evaluated using the probability of Harm to Human (HH). The P(HH) is defined by multiplication of P(HH|CO), P(CO|SV) and P(SV) where P(HH|CO) is the probability of HH given collision (CO), P(CO|SV) is the probability of CO given Separation Violation (SV), and P(SV) is the probability of SV which means there is a violation of a predefined safety boundary. In this study, we focused on P(HH|CO). P(HH|CO) depends on vehicle specifications and operation environments. Thus, in this paper, we assumed a helicopter as rotary UAV fuselage and 4 different operation environments with population density. P(HH|CO) was computed using the lethal area which is derived from the descent angle considering the lift of the propeller. By using the result of this study, safety boundary satisfying Target Level of Safety (TLS) which is a requirement for operation safety can be determined.

Keywords: TLS, probability of casualty, rotary wing UAV