Evaluating the risk of unmanned aircraft ground impacts

Currently many countries are developing regulation to allow unmanned aircraft systems (UAS) operations in their National Airspace System (NAS). Successful integration requires UAS to achieve, at a minimum, an equivalent level of safety to that of manned aviation. Safety is primarily defined in terms of the risk to human life, although potential collateral damages to property can also be taken into account. This paper presents a novel, general, quite conservative and rather simple method that calculates the probability of fatalities and the fatality rates associated with a ground impact. Spatial analysis results are presented that indicate where unmanned aircraft may fly based on obtained reliability and safety levels and provide a coherent comparison of reliability requirements between unmanned aircraft of different families.