Wayne Farley's Aviation Blog - Air Traffic Management

The suspension of flights in and out of the UK’s second busiest airport, Gatwick, after a small drone, or perhaps multiple drones, were spotted over the airport has brought the question of How to stop a Drone? into the limelight.

With hundreds of flights canceled and thousands of passengers stranded, the airport literally ground to a halt between December 19 and 21 due to the safety hazard.

So should drones be shot down, jammed, trapped in a net, or something else? Lots of ideas are being thrown around, but the solution seems to be illusive.

For starters, there is no silver bullet that can be used to eliminate the threat. In order to stop a drone, the first challenge is finding it. The block of airspace around an airport is very large, and by comparison, a drone is like a needle in a haystack.

Drones are too small to be detected by conventional radar, and they are not required to carry transponders to be detected the way commercial airliners are.

In the UK, the authorities deployed helicopters, police officers on the ground, and a military-grade system to find the drone or drones.

But what happens after you have the drone? Speaking on a BBC program, U.K.’s secretary of state for transport, Chris Grayling said “you can’t just fire weapons haphazardly in what is a built-up area around the airport.” So shooting down a drone in the middle of a metropolis is not an option.

Arthur Holland Michel, co-director of the Center for the Study of the Drone at Bard College says that the use of more specialized weapons like military-grade lasers or surface-to-air missiles can work better, but those missiles typically cost far more than the average drone. But here again, deploying them around a commercial airport has the potential to cause more problems than it solves.

The British authorities is reported to be employing a range of options including an Israeli-developed system known as Drone Dome. The system finds the drone by using a combination of radar, cameras and wireless communications sensors. It can then use signal jamming to interfere with the GPS or radio signal to and from the drone.

A report published by Michel in February, found at least 235 counter-drone products either on the market or under active development. Counter-drone technology, also known as counter-UAS, C-UAS, or counter-UAV technology, refers to systems that are used to detect and/or intercept unmanned aircraft.

According to Michel, “we’ve seen things like water cannons, programmable ammunition, lights and lasers to dazzle the drone’s sensors.”

In an entirely different approach to C-UAS, Dutch firm Guard From Above trains large birds of prey to intercept rogue drones in mid-flight. According to Guard from Above, the eagles—which wear protective shin-guards in order to shield their legs from the drone’s rotors—have a 95 percent intercept rate, which is likely higher than many mechanical kinetic alternatives.

Some companies have even developed anti-drone drones that can either fire a net or simply crash into the offending vehicle.

So in the end, the best way to stop a drone, may very well be with another drones.