Safety Considerations for Operation of Different Classes of UAVs in the NAS

Recognizing the significant effort underway to integrate UAV operations in the NAS, a preliminary hazard analysis was conducted for two critical hazards of UAV operation. Models were developed to describe UAV ground impact and midair collisions. Under several assumptions, a model of ground impact was used to calculate the UAV system reliability required to meet a target level of safety, for different UAV classes differentiated by mass. The model showed a significantly higher reliability required for high-mass UAVs, and a large variation in reliability required with population density, with a two order of magnitude increase over metropolitan areas. Midair collision risk was estimated in the vicinity of airways using a model of aircraft collisions based on the density of air traffic in those regions. There is a two order of magnitude difference in risk between on-airway and onaltitude operation and operation away from airways and off major flight levels. Therefore, there are potential operating strategies that can reduce the risk of UAV operation, such as procedural separation from high population and high traffic areas. There are also additional mitigation possibilities to further reduce the risk of integrating UAVs in the NAS. The integration strategies and mitigation requirements are likely to vary greatly for different classes of UAVs.