Paul Bertorelli

Today’s reality quiz: You’re in an airport boarding lounge and the gate agent announces your flight has been delayed because a drone was sighted near the airport. In the improbably fantastical world I’ve created for this blog, the agent asks for a vote: Go or stay on the ground? How do you vote? How do the other passengers vote? I’ll get to my answer in a moment, in the wholly unlikely event that you can’t guess.

Drone hysteria seems to wash over the populace, the media and regulators in cyclical waves. But mostly, the two latter players engage in a toxic game of self-reinforcing hyperventilation while the general public stands by in mild confusion. A 2017 Pew research poll  found that only 11 percent of respondents said the presence of drones scared them. More than half said it made them curious and nearly half said it interested them. Half said keep it away from my house.

But really, shouldn’t these people be terrified? The latest round of pearl twisting occurred last week when the networks breathlessly reported that the FBI was obsessing over drones being flown over Mercedes-Benz Stadium in Atlanta ahead of the Super Bowl. A pilot friend who lives in Atlanta reported that he woke up to the sound of an F-16 cycling in and out of burner, evidently exercising to chase down TFR busters or maybe actually pursuing one. The stadium TFR for the game was an absurdly overbroad 30 miles from the venue, but ahead of that, drones were barred from flying within a mile of the stadium.

I would characterize this as the Twin Stupidities. First, drone operators ought to be aware of the restriction and the sensitivities and accept them at face value. And adhere to them. Second, the government goes just a little nuts in establishing the time and size of these restrictions on stadiums and other sites, finds violators and the press picks up on this as though it were actually a security threat. Rinse. Repeat.

The FBI seized at least six drones as of last Friday. Of course, the real risk of these drone flights is to low-flying helicopters which are themselves buzzing around as part of the security apparatus. Drones are a bona fide hazard to them; I wouldn’t dismiss it. But I’m equally skeptical that the industrial-security complex, in its unending quest for more public money for people and gadgets, isn’t overstating the risk by a little or a lot in placing so many helicopters there in the first place.

And speaking of risk, even people in the industry—you and I—have difficulty putting actual numbers on the risk. It’s two-pronged. The first is what’s the probability of an actual drone collision and second, what are the consequences of a collision. Probability is another name for luck, but calculating the likelihood of a collision is all but impossible because although the FAA reported in mid-2018 that more than a million small drones are registered, we don’t know how often they’re flown or where.

This site tracks drone incidents on a daily basis, but details are sparse because it’s based on press reports. The FAA processes dozens of PIREPs on drone sightings and however reliable these reports are or aren’t, they’re occurring multiple times a day at altitudes between a few hundred feet and up to 10,000 feet or higher.

What real risk these sightings represent is thus far theoretical. You’d like to calculate an accident or collision rate of some kind, but there haven’t been any—or too few to consider a calculation. There are two confirmed drone/helicopter collisions—one in New York, one in Mexico—but other drone encounters have been debunked. For comparison, there are typically half a dozen GA midairs every year and the incidence of these has been trending downward. The actual measured midair fatal risk is something like 0.012/100,000 hours, or less. Tiny. Inevitably, there will be drone/aircraft collisions. Perhaps even enough to better understand the risk.

These guys extrapolated wildlife data as a surrogate for drone strikes and estimated one strike per 374,000 years of drone flight. Or, put another way, the probability of collision with a small UAS is 0.0000306/100,000 drone flight hours. That’s orders of magnitude less than the GA midair risk. I might quarrel with that number on an instinctual basis, but I don’t have any better data. It’s vanishingly low.

You may know that the FAA pegs failure risk for Part 25 aircraft components at 10-9, a number that’s functionally close to zero. The drone risk—at least using the wildlife paradigm—is greater, but still a tiny risk. (It’s 10-5.) And that’s just the probability of a strike, not an aircraft loss. That gets us to outcome.

As far as consequences, we have more data, thanks to the FAA’s ASSURE research work that found that a collision between a small drone and a bizjet or airliner would likely cause more significant damage than a bird would. It found that primary structures—wings, horizontal and vertical fins—could be penetrated and damaged, but windshields were less susceptible. It also found that turbines would be significantly damaged by drone ingestion, just as they would be by birds.

Significantly, the FAA data made no assumptions and offered no probabilities on what effect this damage would have on the outcome of the flight—in other words, would the aircraft survive. You’re left to your own devices to determine what you think the risk is.

For light aircraft, last fall, a private research company, the University of Dayton Research Institute, got into a spat with drone maker DJI over this video. It depicted a DJI Phantom annihilating the wing of a Mooney M20 in a simulated collision. At first, I thought DJI did protest too much, but they made the valid claim that UDRI used the highest conceivable closure speeds, which DJI complained generated four times the impact energy of a more realistic collision scenario.

Perhaps so. Although the scenario exists at the outer edge of the possible collision envelope, it could happen. But the larger question is would that damage take down the airplane? My assessment is that it would not. I’ve seen worse wing damage from birds. If it hit the windshield, well, maybe game over. Life has risks and you can’t zero them all.

Taking this knowledge back into the boarding lounge, when the gate agent asks for the imaginary vote, my response would be why haven’t we left yet. My guess is the majority of passengers would vote similarly. I am thus perplexed at the U.K.’s Heathrow and Gatwick shutdowns because of drone sightings. Gatwick was down 36 hours just before Christmas. In the U.S., Newark had a short ground stop of its own last week.

In my view, given the significant disruption and economic loss associated with such action, these decisions are out of sync with the real risk, which is simply demonstrably low regardless of what demons lurk under your bed. I think the U.K. decision entailed a third kind of risk: the political sort. Looking bad for appearing to be callous about public safety. (If Gatwick shuts down, maybe we should, too.)

What’s to be done? Clearly not nothing. Major airports face an unknown risk from small drones and even though it appears minimal, shutting them down periodically is just not an acceptable option. Every time I attend the drone shows, there are always companies displaying anti-drone technology. It’s a growth industry. These devices sort into two types: RFI weapons that delink the drone from its controller and “kinetic” choices that blast it to bits or capture it physically. Think skeet shooting. Airports may just have to make those kinds of investments.

But there’s a paradox here. If you install that equipment, it will be neither cheap nor 100 percent effective at reducing risk that’s already minimal. It acknowledges the reality that the political class and general public prefer a security edifice with nice window treatments. If airports want true 10-9 probability on drone protection, good luck.

I don’t favor banning the sale of small drones, but if a major airline crash is caused by one—low probability in my estimation—it may come to that. In the meantime, the companies that sell these things, the Academy of Model Aeronautics and perhaps even local law enforcement agencies need to do better in educating the shallow end of the gene pool about the rules for flying small UAS. And for serious violations—flying over crowds and strafing stadiums—a few applications of draconian fines might help.

The FAA does pursue civil penalties, but enforcement has been uneven at best. For example, the guy who flew his DJI onto the White House lawn was fined $5500. The owner of a drone chased down by an NYPD helicopter in 2014 was fined $1600, but mitigated it to $800. The FAA reserves the right to revoke a pilot’s certificate—for manned aircraft—for a drone violation. And it did just that to David Quinones in 2015. The FAA pulled his commercial certificate for three months following a drone flying incident in New York in which he claimed not to have violated any aspect of FAR 107.

And however much I might think TFRs around stadiums are government overreach, rules are rules. If you’re of a mind to ignore them, you’re an idiot. Stop doing it.