The team detected 24 instances between August 2018 and July 2021 in which drones came within 500 feet of a piloted aircraft in a single location.
Researchers at Embry-Riddle Aeronautical University in Florida and Unmanned Robotic Systems Analysis (URSA) have developed a new way to accurately count and objectively analyse close encounters between drones and aeroplanes – without depending solely on pilot sightings.
The team analysed over 1.8 million piloted aircraft operations and nearly 460,000 flights by small, uncrewed aerial systems (sUAS) around Dallas–Fort Worth airport.
During a three-year period, the team identified 24 near-midair collisions (NMACs) between sUAS and aircraft, including two in 2018, one in 2019, 14 in 2020 and seven in 2021. The majority of close calls occurred within 1.5 miles of a runway approach or departure zone.
To avoid collisions, the researchers recommended extending the runway exclusion zone for drones at the end of high-risk runways from around one mile to 3.5 miles.
“That modification would provide enhanced protection for piloted aircraft operating at less than 500 feet above ground level during approach or departure,” said Ryan Wallace, one of the study’s authors. “Typically, small, uncrewed aircraft don’t fly above 400 feet.”
Drone flying close to a plane / iStock
Image credit: iStock
Until now, the majority of information researchers had on near collisions between drones and planes was pilots’ personal experience. Using only this data, the Federal Aviation Administration (FAA) recorded 2,596 of these encounters in 2021 – more than double the 1,210 reports during the first full calendar year of tracking in 2015.
The goal of the Embry-Riddle researchers was to devise a more reliable way to gather detailed information about NMACs between drones and aeroplanes.
To do so, the team relied on an unmanned aerial system detection device connected to an antenna on top of Dallas–Fort Worth airport’s busy Terminal C concourse. For each sUAS within a 30-mile radius, the device captured telemetry, altitude, launch location and other details.
Researchers combined that information with ADS-B (automatic dependent surveillance-broadcast), as well as Mode S messages transmitted by aeroplanes and tracked by the OpenSky Network. All this information was then fed into URSA’s Airspace Awareness Platform, or AAP-NMAC – a proprietary data analytics software.
“We hope that our findings will help improve aviation safety by reducing the risk of collisions between unmanned aircraft systems and piloted aircraft operating in the national airspace system,” Wallace said.
Across all the 24 close-call events the system detected, the mean lateral distance between the drone and the aeroplane was only about 215 feet. Commercial air carriers were involved in 11 NMACs, while seven incidents involved helicopters and six involved general aviation aircraft.
All of the helicopter encounters happened within 1.25 miles of a heliport. Similarly, in 10 of the 11 air carrier encounters, the aircraft was within 1.5 miles of approach or departure and lower than 500 feet above the ground.
“Operations within the vicinity of an airport are critical flight phases for pilots with high workload levels. It is within these areas where aircraft have added susceptibility of a collision with sUAS,” said Scott Winter, co-author of the research article. “The findings from this study provide objective data for operators, government agencies and airlines to understand sUAS operations better and prevent possible conflicts.”
As of 2020, an estimated 1.46 million sUAS were operating in the US national airspace system, the FAA has reported. By 2025, the FAA predicts the small sUAS fleet will include nearly 2.4 million units.
“The proliferation of drones, particularly ones available to the general public, poses obvious risks,” said research collaborator Dr Stephen Rice. “Unfortunately, not all drone operators are responsible, knowledgeable or safety-minded. Many of them are not even aware of the rules they must follow.”
In the majority (96 per cent) of the near collision events recorded by the team, the drone was operating in excess of the maximum permissible altitude for that area.
The researchers’ findings were published in the SAE (Society of Automotive Engineers) International Journal of Aerospace.
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