Operating small unmanned aircraft systems (sUAS) beyond visual line of sight (BVLOS) without appropriate waivers and risk mitigations presents a serious hazard to manned aircraft and other users of the National Airspace System. According to federal regulations codified in 14 CFR 107 and PL 112-95 Sec. 336, sUAS operators are required to fly their craft within visual line of sight. Currently, no data exists to determine if operators are compliant with these rules. The authors sought to conduct an exploratory research study to determine the distance operators fly their sUAS craft and evaluate the likelihood of remaining in visual contact using modeling techniques. Using the DJI AeroScope detection device, the authors sampled 30 days of sUAS flight data from a location in the southern U.S. Collected data included operator location, unmanned aircraft model, flight telemetry, and other ancillary information. The authors amassed data for 1,013 sUAS flights, however, only 110 flights included the necessary information to determine distance information between the operator and aerial vehicle. Using Greening’s (1976) visual modeling technique, the authors calculated maximum visibility distances for the sUAS models based on size and human visibility limitations, and compared them against detected distance findings. The authors determined that 5.5% of the detected flights were flown at distances exceeding human visual limits. The authors plan to conduct future field studies to compare the calculated visibility models contained in this paper in field test conditions.



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