Characterizing Observer Sense of Safety When Witnessing Complex Aircraft Trajectories

As the number of unmanned aerial vehicles (UAVs) in low-altitude missions is increasing, it becomes crucial to ensure that people feel safe under that air space and as passengers on aircraft. Ideally, UAVs should operate in a manner that is both safe and predictable to non-expert human observers. This study examines how people rate airspace safety and collision likelihood when witnessing simulated UAV aircraft trajectories of varying complexity. Participants rated each scenario based on their perception of the likelihood of collision (PLC) and sense of safety (SoS), providing insights into how humans assess flight safety as both passengers inside an aircraft and ground observers. The results reveal important aspects of human safety perception while witnessing crowded airspaces. Observers on the ground report feeling less safe compared to those inside the aircraft, highlighting the influence of perspective on safety perception. Furthermore, the complexity of UAV trajectories does not linearly correlate with perceived safety; instead, curved trajectories such as sinusoidal and looped paths are particularly associated with a decreased sense of safety when viewed from the ground. These findings suggest that human observers struggle to accurately assess safety in complex flight scenarios, emphasizing the need for UAV designers to consider how people will view the vehicle's behavior.