A study conducted in the skies around Daytona Beach airport in May revealed "troubling" findings about the frequency in which unmanned drones are flown close to U.S. airports, the study's authors wrote.
"It is very likely that operations of UASs [unmanned aerial systems] are much more frequent than we would expect," Ryan Wallace, an Embry-Riddle assistant professor of aeronautical science, who was lead author of the study, said in an interview. "These operations create potential risk for aeronautical activity and manned aviation, particularly because of their proximity to airports and other manned aviation activities."
During the 13-day study, the researchers used a drone signal monitor called a DJI AeroScope to detect small drone activities near the Daytona airport. Over that time, they detected 192 drone operations into the airport's airspace -- almost all of them within a five-mile radius of the airport and at an altitude of 1,000 feet or less.
The authors noted two particularly worrisome incidents. In the first case, a drone was operated along the coastline at 462 feet of altitude, where it was in close proximity to two aircraft that the authors presume to have been banner towing operations.
Even more egregious, the authors said, was the second incident, in which a drone was detected at 90 feet of altitude and within .25 nautical miles of the Daytona Beach airport approach path. Just seconds before that detection, the study says, an aircraft was on approach to the airport.
"It is highly probable that the aircraft descended through the UAS altitude while on approach," the authors wrote.
"Considering that close encounters with other aerial objects are generally rare events, finding two within the span of a 13-day sampling period is particularly troubling," they added.
In the interview, Wallace noted that larger airports, which tend to be in more densely developed areas than Daytona airport, are likely surrounded by more drone activity.
Embry-Riddle also monitored drone activity in the skies to the south of Tampa airport this spring, where they detected higher than expected drone activity, Wallace said. A paper reporting the results of that study is under peer review and is likely to be published soon, he added.
The Embry-Riddle study follows the U.S. Government Accountability Office's revelation in May that the FAA collected 6,117 reports of sightings of potentially unsafe drone use between February 2014 and April of this year.
Though federal regulations restrict drone use in key air space, including in air space around commercial airports, Wallace said that many operators don't follow the rules.
"It really comes down to continuing to promote education so that people understand these drones are tools not toys, and that when they are flown as toys the rules need to be respected," he said.