What happens when a drone hits a plane?

You know the rules by now: Don’t fly your drone anywhere in controlled airspace where it might conflict with manned aircraft — unless you have a specific reason for making the flight, have all requisite permissions or waivers from the FAA or your local regulatory authority — and really know what you’re doing. Why? You’ll see.

The phenomenal growth of drones in the past seven years has given rise to a tremendous number of new use-case scenarios. Drones are being used for mapping, security, Search & Rescue, high-end videography and photography, surveying, archaeological research, police work, and more. And while there’s recognition now of the many amazing things that drones can do for us, there’s also concern about the potential dangers posed by drones. Specifically, what might happen if a drone collided with a manned aircraft. What damage might be caused? Researchers have been trying to get an answer to this question.

A deliberate collision

One of the ways to test what might happen is to have an actual collision between a real aircraft and a drone under controlled circumstances. And recently, in Hungary, that’s precisely what they did. Using a Russian-built Antonov AN-2, a series of collisions were staged. One of them hit the biplane’s strut, another the bottom surface of the lower airfoil, and a third was buzzed through the propellors.

The video is in Hungarian, so you may want to scrub ahead to the various collisions, which are followed by slow-motion shots and then a look at the damage.

Bigger than a Cessna…

In this case, the research was being done in scenarios as close to real-world as they could make them. And while the data here is useful, it doesn’t represent what might happen with a smaller aircraft – or at higher speeds. Some of those who commented on the YouTube video suggested that the AN-2 is built like a tank, and may not have necessarily been the best aircraft for this kind of test.

Even though the damage to the AN-2 seems superficial, it would still take several hours to repair taking this aircraft out of service. More than likely an aircraft of this size would receive superficial damage if it was to strike a drone but the potential is there to cause catastrophic damage (on a smaller aircraft)

Joe Morales, YouTube User

Back to the lab again

Another way of conducting these kinds of tests is in the lab. It might not be as “real-world,” but tests can be conducted without risking damage to an aircraft or potential injury to a human. In these tests, people at the University of Dayton Research Institute fired an older Phantom 2 at the leading edge of a Mooney M20 aircraft wing. The drone was fired using a compressed air cannon, with the UAV impacting at 238 MPH – a figure that would soon be challenged. This is what happened at that speed:

Realistic?

It’s pretty clear, in this example, that the drone would have caused serious damage if a dead-on collision had occurred at this speed. But this is a maximum speed for that aircraft, not the kind of speed it would routinely be flying during takeoff or landing. And it’s during that procedure, when the aircraft is at lower altitudes, that a collision is more likely to occur.

Immediately after this research was publicized, DJI took issue with how the research was carried out. Flying at 238 MPH, said the company, was unrealistic – and assumed maximum speed for the aircraft and greater than the maximum speed the Phantom 2 was capable of. DJI also suggested that the research revealed that a bird strike would cause more damage than a drone – but that the bird strike was minimized.

UDRI staged its video to create a scenario inconceivable in real life, at a higher speed than the combined maximum speed of the drone and airplane, which is also faster than U.S. Federal Aviation Administration (FAA) testing guidelines. UDRI has not disclosed its testing methodology or the resulting data, and while it acknowledged that a similar test with a simulated bird caused “more apparent damage,” it has only promoted the video showing damage from a DJI drone.

DJI Statement

Pushback

DJI pushed back, and hard. The company’s Vice President of Policy and Legal Affairs, Brendan Schulman, called much of the research methodology – and the publicized conclusions – into question.

…The impact velocity tested, 238 mph, far exceeds any conceivable collision speed between a Mooney M20 and a DJI Phantom 2. The M20J Pilots Operating Handbook lists the maximum structural speed of a Mooney 20 at 174 knots, which is 200 mph. Cruise speed will typically be 140-160 knots (161-184 mph), more than a mile above ground. The Phantom, and our other drones, have built-in altitude limitation features.  Thus in the altitudes no higher than several hundred feet above ground where a drone is likely to operate, the Mooney M20 would be taking off or landing at speeds between 70-88 knots (81-101 mph).

Brendan Schulman, DJI

The DJI refutation is quite lengthy, and ultimately ends with this Call to Action:

We respectfully demand that you withdraw your research, remove the alarmist video from circulation, and issue a corrective statement to the public and to all of the media outlets you have appeared in, acknowledging that the configuration of the test was invalid given the flight envelopes of the two aircraft tested, FAA testing standards, and the limited value of a single test.

Brendan Schulman

The video, which received wide play by media outlets, reflected an unrealistic scenario. The Dayton Daily News quoted DJI’s North America Communications Director, Adam Lisberg, as saying the following:

What this video shows, is that if you take the wing of a small airplane and fire something at it at hundreds of miles an hour, you will damage it. I could have told you that.

Adam Lisberg

The DJI bias

You have to feel for DJI a bit. Because the manufacturer sells more drones than anyone else, these are the drones most often selected for any tests around drone safety. And, when the images from such tests go briefly viral, an impression is left associating DJI with these impacts and subsequent damage – even though if the deliberate collision happened to involve questionable testing methodology..

Newer, smaller, lighter

The trend, at least with DJI, seems to be toward smaller and lighter consumer drones. A Mavic Air 2, for example, is much smaller and lighter than that Phantom 2 (which looks almost antique now – and was two years old at the time the research was carried out). It would seem much less likely to cause a problem than the older generation. An Inspire 2, of course, would be heavier. But the odds are that someone owning a higher-end drone like that would be a professional and unlikely to be flying where it might come into conflict with manned aviation. (And a Mavic Mini? At 249 grams, it would pose the least risk.)

Use your brains

We’re not engineers. We can’t say, with great certainty, what the risks are. What we can tell you, however, is that if a collision did lead to damage to a manned aircraft, the stakes are potentially very high. And so it’s simply not worth the risk – ever.

Fly your drone where it’s supposed to be. Avoid flying near airports. Obey the rules. And, as the FAA likes to say, Know Before You Fly.