By how much of a threat is that, you ask? According to researchers Eli Dourado and Samuel Hammond, injury caused by a drone collision would likely only happen once every 1.87 million years. For the sake of reference, the duo analyzed 25 years of what the FAA calls “wildlife strike” data, that is, a list of reports filed optionally by pilots after they’ve experienced an in-flight collision with birds. As they combed through more than 160,000 different reports, Dourado and Hammond found that only 14,314 of the collisions caused any serious damage — in other words, just 11 percent caused damage.
In fact, the research also showed that birds crowd the skies (and get in the way of commercial and civilian aircraft) substantially more than drones do, despite reported media claiming the opposite. Moreover, the complete analysis of the wildlife strike data pushed Hammond and Dourado to conclude that the chances of a plane striking a bird are significantly higher than one striking a drone. They went so far as to say “contrary to sensational media headlines, the skies are crowded not by drones but by fowl.”
Further clarifying their point, the researchers note that the most severe aircraft accidents are always the product of an impact with a large bird, with some 398 total injuries ever having been reported. What skews this data even more is the fact 100 of those injuries came during a 2009 US Airways crash into the Hudson River in which a flock of geese was sucked into the plane’s engines shortly after takeoff. Additionally, the 25 years of available data only show 12 fatalities caused by wildlife strikes on aircraft with just one occurring to someone aboard a commercial flight.
“Not a single one of the fatal incidents involved a bird that was reported as ‘small,'” Hammond and Dourado say in their research. “Bird strikes provide an excellent parallel phenomenon for estimating the magnitude of damage a small UAS could cause my colliding with a manned aircraft. To date, a UAS has never collided with an aircraft in U.S. airspace.”
What makes Hammond and Dourado’s research seem even more credible is that they aren’t the only ones who’ve dug through data and come up with similar conclusions. In a 2015 study conducted by the Academy of Model Aeronautics, research showed the accuracy of reported near-miss incidents between an airplane and small drone appears to be wildly off. The most strikingly errant statistic concerned just how much of a “close call” each of the 764 near-misses actually were. According to the AMA, just 27 (or 3.5 percent) could feasibly be designated as near misses or near collisions.
“The FAA needs to better analyze and categorize pilot reports to indicate which present serious safety risks (near mid-air collisions) and which could be more appropriately classified as sightings,” the AMA suggests in its research. “Contrary to the FAA’s assertion in its press release of August 12, and the widespread media reporting that followed, the narrative descriptions and notations in the 764 reports suggest that the number of actual ‘close calls’ appears to be in the dozens, not hundreds.”
Hammond and Dourado in their published findings acknowledge that birds and drones are comprised of different materials. They concede that this fact could render drone-aircraft strikes more likely to cause damage than bird-aircraft collisions but stress that they do not have a way to “empirically assess” the assumed damage accrued by a UAV’s rigid materials. Neither of them, however, find the existing evidence compelling enough to deem drones an immediate threat to airspace. Instead, they feel the probability of a collision is at an “acceptable level.”
