Researchers have counted 241 near-collisions between drones and manned aircraft in the U.S., a finding that is sure to add to growing concern over how to regulate what has become a increasingly popular commercial gadget.
In a report issued on Friday, Bard College's Center for the Study of the Drone researchers said that of the 241 incidents that met the Federal Aviation Administration's definition for near-collisions — with a drone-to-aircraft proximity of less than 500 feet — 90 involved commercial jetliners.
Some near collisions were razor thin — 51 of the sightings were reported as being as close as 50 feet or less.
The FAA prohibits unmanned aircraft within five miles of any airport without
permission from air traffic controllers.
The Center for the Study of the Drone, which based its findings on data from the FAA reports and Department of Interior, cautioned that exact distances can be hard to judge by pilots traveling at high speeds. Still, the numbers were a clear indication of the dangers posed by the general public's increasing embrace of unmanned drones.
Federal regulators have been grappling with how to reconcile the commercial popularity of drones with the need to keep skies clear for aircraft. For example, the potential of a mid-air collision has on multiple occasions forced water-dropping aircraft to temporarily avoid a fire zone, infuriating firefighters.
As part of an effort to bring more accountability to the market, the U.S. Department of Transportation in October announced plans to require every drone to be registered with the federal government by the end of the year.
Overall, the new report, which includes data from between Dec. 17, 2013, and Sept. 12, 2015, found that there were 921 incidents involving drones and manned aircraft — 64% of which posed no safety threat.
The urban areas with the highest number of reported close-call incidents were New York/Newark, 86; Los Angeles, 39; Miami, 24; Chicago, 20; and Boston, 20.
Dan Gettinger, co-director of the Center for the Study of the Drone, said in a statement that the findings add "a critical layer of detail and context to the conversation on the use of drones at home."
“We are looking to furnish stakeholders and the public with a reliable, data-driven guide to the potential risks posed by drones to manned flight," he added.
Manufacturers currently test the structural integrity of aircraft engines by firing dead birds at them at high velocities, but the FAA hasn't said when it will require tests with drones.
Meanwhile, the Associated Press reported that the number of drones spotted flying in restricted airspace has increased dramatically. In May 2014, 10 incidents were reported to the FAA; in May 2015, there were 100 incidents.