Bard College: “Drone Sightings and Close Encounters with Airplanes on the Rise”

A recent study from the Bard College Center for the Study of the Drone evinces an increase in the dangers drones pose to manned aircraft since late 2013.

Pilots have reported an increasing number of incidents with drones. This increase has occurred as interest in drones has grown the past few years, despite a framework of rules designed to ensure aircraft safety. By Federal Aviation Administration rules, drones may not be operated within 5 miles of an airport or at an altitude above 400 feet.

The study sought to understand “why” the aircraft-drone incidents were occurring and to discuss potential solutions to the problem. After reading the study, though, it is unclear whether the authors were able to ascertain “why” the incidents occurred, beyond the increase in the number of drones operated in the United States’ airspace.

The study looked at “close encounters” and “sightings” of drones. The study defined a “close encounter” as where a drone comes within 500 feet of a manned aircraft, when a pilot declares a “Near MidAir Collision,” when a pilot takes evasive action, or when the pilot uses descriptive language that indicates the drone as being dangerously close (for example: “almost hit” or “passed just above”).

The first three criteria are objective. It is relatively easy to determine when a pilot states a drone came within 500 feet of an aircraft. Similarly, researchers can discern when a pilot uses certain language, or takes evasive action. The final criteria, though, can be subjective, relying both on the judgment of a pilot and on the discernment of the researcher.

The study also states a “sighting” occurred when a drone was “spotted above its legal ceiling or in the vicinity of an airport or aircraft, but does not pose a clear potential for a collision.”

With those definitions established, the study analyzed 921 “incidents”, classifying 64.5 percent of those incidents as “sightings” and 35.5 percent of them as “close encounters.” Some of the study’s findings include:

  • Where pilots reported the distance from an airport of an incident, almost 60 percent of the aircraft-drone incidents occurred within the five mile “no-drone zone”;
  • Where pilots reported the altitude of an incident, roughly 90 percent of the aircraft-drone incidents occurred at altitudes above 400 feet and 28 percent occurred above 4,000 feet; and
  • Most incidents were reported by single engine propeller aircraft, which generally operate at lower altitudes than commercial jets;

The study includes a number of proposed solutions, from Geo-Fencing to Sense and Avoid Technology to drone registration and better operator education. Some of the solutions seem to reflect common sense. Other solutions do not appear aimed at any particular problem or by admission will not address causes underlying the incidents.

Geo-Fencing is software installed on drones that prevents them from operating within FAA restricted airspaces. For example, drones with geo-fencing software would not fly within 5 miles of an airport or at altitudes above 400 feet.

Sense-and-Avoid Technology uses a drone’s camera to detect obstacles and uses software installed on the drone to avoid the obstacles. While the technology is not fully developed, the FAA is working with manufacturers to develop common standards.

The FAA has proposed rules requiring all drone operators to register their drones with the FAA. The drones would have “tail” numbers, which would allow for easy identification in the event of an “incident”. At least, that is what the FAA and proponents of the registration system claim, but the study seems to admit drone registration will do little to curb aircraft-drone incidents as “many of the incidents in our database involve drones operating at relatively large distances from manned aircraft, it may not always be possible for the reporting party to identify the registration number on the drone.”

Despite these findings and proposed solutions, the study does not address the problem underlying the increase in incidents. It is unclear whether the number of “incidents” has increased due to lack of operator education, software flaws allowing drones to operate in “no-drone zones,” or deliberate forays into restricted areas.

The Bard College Study lays a good foundation for establishing a baseline for future studies. Other than linking the increase in aircraft-drone incidents to an increase in the number of drones sold, the study failed to examine any other potential causal factors between incidents and drone operators.  Without understanding why the number of incidents has increased beyond the explosion of interest in drones, it is impossible to craft meaningful solutions to address those incidents.

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