A new report from the Mercatus Center of Virginia-based George Mason University has determined that the risk of a collision between small unmanned aircraft systems (UAS) and manned aircraft in the National Airspace System is “minimal.”
The report – authored by Eli Dourado (who recently testified on drones at a Senate committee hearing) and Samuel Hammond – pulls numbers from the Federal Aviation Administration’s (FAA) wildlife strike database, which offers information on animal collisions with manned aircraft from 1990-2014.
“When large birds are ingested in jet engines, they may cause substantial damage, including crashes,” says the Mercatus report. “While these birds do not number in the billions, they still maintain a significant presence. The U.S. is home to nearly 1.9 million turkey vultures, for instance, and between 2 to 3 million snow geese enter the United States each winter,” the report says.
“Contrary to sensational media headlines, the skies are crowded not by drones, but by fowl.”
Of the 160,000 reported wildlife strikes in the past 24 years, 14,314 of them “resulted in damage” to the aircraft, and 80% were from medium or large animals, the report says.
However, it explains, 238 incidents have occurred with either injuries or fatalities, but only 37 have been related to commercial aviation: e.g., not government or privately owned aircraft.
“We should view these 37 incidents over more than 25 years in the context of approximately 27,000 commercial flights per day,” the report says. “In more than 25 years of data, only 12 wildlife strike incidents resulted in fatalities.”
In addition, of these 12, only one aircraft was a commercial airliner, an Atlantic Southeast Airlines plane that “hit a pair of white-tailed deer on its landing roll” in 2000, according to the report, which adds that “not a single one of the fatal incidents involved a bird that was reported as ‘small.’”
Dourado and Hammond estimate that “damage to an aircraft will occur in around 20 percent of strikes with animals weighing around 2 kg” and that “the probability of the incident resulting in passenger injury or death is about 0.2 percent for animals weighing around 2 kg.”
Taking into account a reported 13,414 collisions – counting both birds and flying mammals – in 2014 and an estimated 10 billion birds in national airspace, the study estimates that “plausibly 1 bird in 1 million collides with an aircraft every year.”
“Even if we take UAS operators to be about as deliberate and skilled at avoiding aircraft as birds, we cannot similarly estimate that 1 UAS in 1 million UAS will collide with aircraft every year.”
At the recent Senate hearing, Capt. Tim Canoll, president of the Air Line Pilots Association, International, said, “We know that unsafe situations involving UAS are occurring right now. Each month, the Federal Aviation Administration receives more than 100 reports of UAS sightings from pilots and others.
“While it is almost certain that these events involved recreational rather than commercial UAS operators, they demonstrate the need for UAS pilot education and enhanced safety.”
The Mercatus Center report notes that drones and birds are, of course, made of “different materials,” so the magnitude of damage from a drone could be greater. In addition, jet engines are not required to go through tests for drone strikes as they do for birds.
However, the study concludes that small UAS (weighing under 2 kg) “pose a negligible risk to the safety of the national airspace.”
“We estimate that 6.12×10−6 collisions will cause damage to an aircraft for every 100,000 hours of 2 kg UAS flight time. Or, to put it another way, one damaging incident will occur no more than every 1.87 million years of 2 kg UAS flight time. We further estimate that 6.12×10−8 collisions that cause an injury or fatality to passengers on board an aircraft will occur every 100,000 hours of 2 kg UAS flight time – or once every 187 million years of operation.
“This appears to be an acceptable risk to the airspace.”
Last year, in response to the FAA’s publicly released report on drone activity near manned aircraft, the Academy of Model Aeronautics issued its own analysis of the data, which the group said revealed a more complex picture than initial headlines had suggested. According to AMA, some of the FAA’s reports did not involve drones at all, and only a fraction of the records were truly “close calls” or “near misses.”
The full Mercatus publication can be found here.