(Bloomberg) — The millions of small civilian drones plying thenation's skies can cause significant damage to airliners andbusiness jets in a midair collision, new research commissioned bythe U.S. Federal Aviation Administration concluded.

While most drones weigh only a few pounds, they include motorsand other metal equipment that could cause significant damage to aircraft engines, windshields orwings upon impact, according to the study by an FAA researchcenter.

Even though airliners and other aircraft are designed to takeimpacts from birds, “it doesn't mean they are going to be able towithstand a 4-pound or an 8-pound UAS impact,” said GerardoOlivares, a researcher at Wichita State University who helped leadthe study. He referred to drones as UAS, or unmanned aerialsystems.

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The results of the government-sanctioned study, the mostcomprehensive of its kind to date, add urgency to FAA's efforts toimprove safety as the industry pushes to expand droneoperations in everything from delivering consumer goods toperforming aerial inspections. It also comes on the heels of thefirst two midair collisions between small drones and traditionalaircraft in North America.

Last month the FAA said reports of drone-safety incidents,including flying improperly or getting too close to otheraircraft, now average about 250 a month, up more than 50 percentfrom a year earlier. The reports include near-collisions describedby pilots on airliners, law-enforcement helicopters or aerialtankers fighting wildfires.

The agency estimates that 2.3 million of the devices will besold for recreational use in the U.S. this year. As of Nov. 3, morethan 838,000 people had registered with FAA as owners of small,civilian drones.

Researchers at four universities conducted impact tests andcomputer modeling over the past 14 months, attempting to determinethe potential hazards to common single-aisle airliners and businessjets. The work was peer-reviewed by NASA and aircraftmanufacturers, Olivares said.

The researchers said that drone manufacturers could reduce thepotential risks if they used less metal in their devices. Theresearch also highlights the need for automated systems on dronesthat sense other aircraft and move out of the way, they said.

Crash dynamics

Olivares, who is director of crash dynamics at Wichita State'sNational Institute for Aviation Research, said it didn't appearthat any of the impacts from a 2.7-pound (1.2-kilogram) quadcopteror a 4-pound fixed-wing model plane would prove catastrophic toairplanes.

The 4-pound model plane was capable of causing severe damage —defined as penetrating the fuselage and damaging an aircraft'sinternal structure — in a collision with multiple areas of the tailfins on a jetliner such as the Boeing Co. 737.

In addition, jet engines were likely to suffer more seriousdamage from such small drones than a similar-sized bird.

“The Federal Aviation Administration will use the researchresults to help develop operational and collision risk mitigationrequirements for drones,” the agency said in a press release.

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Falling drones

A separate set of tests released by FAA released earlier thisyear found that small drones popular with hobbyists and somecommercial photographers were unlikely to cause serious head andneck injuries if they fell from the sky and hit people. A study byresearchers at Virginia Tech in Blacksburg, Virginia, reachedsimilar conclusions.

Separate from the FAA-sponsored tests, accident investigators inthe U.S. and Canada are looking at the damage caused by two actualcollisions with aircraft.

An Army helicopter struck a SZ DJI Technology Co. Phantom 4drone on Sept. 21 near Staten Island, New York. The device damagedthe UH-60 Black Hawk chopper's rotor blade, window frame andtransmission deck, according to a preliminary report by theNational Transportation Safety Board. The helicopter crew landedsafely.

On Oct. 12, a chartered turboprop carrying six passengers andtwo crew members struck a drone at about 1,500 feet (457meters) altitude as it prepared to land in Quebec, according to theTransportation Safety Board of Canada. The Beechcraft King AirA100, which sustained minor damage to the left wing, landed a shorttime later and there were no injuries.

Current regulations in the U.S. and Canada include provisionsdesigned to prevent drones from operating near aircraft. In mostcases, drones are supposed to stick to low altitudes below whereaircraft operate and they aren't allowed to fly near airportswithout special permission. But the upswing in reported safetyincidents suggests that many unmanned operators either ignore therules or don't know them.

Determining the risks of a midair collision between drones andtraditional planes and helicopters is critical to opening the skiesto greater uses of drones.

Companies ranging from retail and technology giants Amazon.comInc. and Alphabet Inc. to startups such as Flirtey Inc. are hopingto capitalize on drone technology to make commercial deliveries. Atthe same time, other businesses want to expand the use of unmannedcraft for aerial inspections, from Berkshire Hathaway Inc.'s BNSFRailway to Farmers Insurance Group.

Even though these companies plan to fly at low altitudes belowmost human-occupied aircraft, the FAA could impose stricter safetysystems on such drones if collisions could cause catastrophicdamage.

The crash-study results could also steer FAA on its policies forenforcing existing drone-flight rules. As incidents rise, the FAAmay be more inclined to seek fines or criminal penalties on droneusers who flout the rules designed to keep them away from otheraircraft.

The study released Tuesday was done by the Alliance for Safetyof UAS Through Research Excellence, an FAA-sponsored center ofexcellence that goes by the moniker ASSURE.

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