At 9pm on December 19th, the UK’s second busiest airport, London Gatwick, was shut down after a drone was spotted flying over the perimeter fence and towards the runway.

What ensued was nothing short of chaos. Over the next 36 hours, further sightings were reported, more than 1,000 flights were diverted or cancelled, and around 140,000 passengers had their Christmas travel plans disrupted.

The incident made international headlines, partly because police claimed whoever was responsible was using equipment that was “adapted and developed” to avoid detection. Rather than a stupid hobbyist or an accidental flyaway, officials painted the incursions as entirely deliberate.

The entire fiasco was devastating for the reputation of Gatwick’s security team, as well as the notion that major airports are prepared for what is a very modern threat.

The question on most observers’ lips was, ‘How?’

How could a heavily protected, highly surveilled and vital infrastructure location in one of the world’s major cities be crippled by a single drone? How was it that police and airport security were unable to apprehend the person or people responsible and were very publicly losing what they described as a game of “cat and mouse”?

And how is it that now, almost three months later, we are still no closer to understanding what happened or who was responsible?

In a very predictable turn of events, similar shutdowns have occurred at airports around the world since: On the other side of London at Heathrow airport, in Dubai and in New Jersey. Perhaps the number of these incursions really is on the rise. But more likely is that overzealous security staff are spotting lights in the sky and jumping to the wrong conclusions. Who knows, that may even be an element of the multiple sightings at Gatwick in the first place.

As you might expect, counter drone companies have also been seeking publicity, explaining how their particular technology would have prevented the Gatwick incident.

There are several ways to stop drones from flying where they shouldn’t. Some are more effective than others, and there doesn’t appear to be a silver bullet on the market as of yet.

Here are some of the ways that companies around the world are proposing to deal with the drone problem.

Kinetic methods

If you had taken a poll across the UK during the Gatwick incident and distilled public sentiment down to a single sentence, “Shoot that thing down” would be pretty close to the result.

But shooting down rogue drones is rarely the best option. For starters, gravity dictates that the drone is going to crash down somewhere and potentially on someone. Even if the immediate area isn’t that sensitive, minor damage to a drone from a partial hit could cause it to veer off in one direction and crash who knows where.

There’s also the issue of forensic data. If you obliterate any threat on sight, it’s going to be much more of a challenge to recover evidence and find out who was responsible.

More complications arise if you assume, as the officials in London did, that the drone was being operated by a sophisticated group or individual. The UAV could be weaponized or rigged with explosives. Security teams want control at this point, the ability to dictate proceedings rather than react to them. Opening fire doesn’t necessarily grant those things.

As a result, several attempts have been made to develop systems capable of capturing rogue drones in mid-air.

These include the SkyWall 100, a shoulder-mounted bazooka from British company Openworks Engineering. The system locks on and fires a net to snag drones and bring them safely down to earth.

Another net-based solution has been developed in the Netherlands. Dutch company Delft Dynamics’ DroneCatcher is designed to be deployed during an incident. It’s essentially a bigger drone fit with a camera, laser rangefinder and net. All of which allows it to catch rogue drones in the act and drag them away to safety. US-based Fortem Technologies’ DroneHunter takes a similar approach.

The most recent addition to the net-based scene came earlier this month, when the US Army patented a grenade featuring a proximity detector and net-firing mechanism. This concept is the most future-proofed we have seen, designed to handle swarms of rogue drones rather than single incursions.

Frying & Hacking

Using electromagnetic energy to disable a drone’s onboard circuitry is one way to drop it out of the sky in a heartbeat.

Military hardware specialists Raytheon have developed a high-energy laser that does exactly that.

Ultimately the threat is brought down to Earth, but a move that direct may not always be the safest or the smartest for the reasons already outlined above.

But Raytheon’s steps in the counter drone space suggest the company is already aware of this and looking to expand its options. Last year, Raytheon partnered with Maryland-based counter-drone company Department 13.

Department 13’s MESMER system can jam radio signals but also effectively hijack rogue drones. It works by manipulating radio protocols to snatch control from the pilot. From that point security teams can force the drone to stop, hover, redirect or land. It’s easy to see how, when used in conjunction with Raytheon’s more direct methods, it could provide an adaptable counter drone measure at events and sensitive locations.

MESMER also gives security teams the ability to white-list friendly drones and remove uncertainty from security operations, which is handy considering that law enforcement agencies are increasingly adopting the technology for their own purposes.

Jamming & Spoofing

Next we get to measures that aim to interfere with the drone’s own sense of position or interrupt the connection between drone and operator: spoofing and jamming respectively.

San Diego startup Citadel Defense Company is developing a jamming system that can detect wifi and radio control protocols before applying a machine learning algorithm to create a jamming signal that ensures interference is restricted to the target. One of the biggest concerns with the use of jamming technology is the fear of collateral damage, so that’s kind of precision a big step.

There are several companies with similar-looking solutions that have gained traction in the past couple of years.

Israeli company Rafael has seen its Drone Dome deployed by military and government agencies around the world. The DroneGun from DroneShield is another shoulder-mounted option that can disrupt rogue drones from over a mile away. DroneShield says the system offers signal jamming across the 2.4 and 5.8 GHz frequencies, as well as the ability to block GPS and GLONASS.

Dedrone and Ohio-based Battelle have been working on a complete, combined system that detects, tracks and mitigates against rogue drones. Battelle’s DroneDefender is restricted to use by federal authorities and buyers have to undergo a strict permitting process. It’s a portable point-and-shoot countermeasure that uses disruptive radio waves to jam a drone’s connection to the pilot and GPS.

No Silver Bullet

The reason there’s no silver bullet drone countermeasure is clear: the sheer variety of threats and potential scenarios make developing a one-size-fits-all solution close to impossible.

That’s why, looking forward, it’s likely that we’ll see sensitive locations continue to deploy multiple systems that attempt to provide situational awareness and active countermeasures.

The technology exists to stop most off-the-shelf drones from flying where you don’t want them to, but even then situations are complicated by external factors: people and property in the line of fire, sensitive infrastructure that could be damaged or disrupted with the use of jamming systems or EMPs, rogue drones with dangerous payloads.

It’s also fair to say that the majority of solutions available today aren’t particularly future-proof. How well will point-and-shoot methods work when multiple drones are approaching, for example? And what will happen when computer vision and onboard AI undermine countermeasures seeking to disrupt radio control and GPS?

That future-proof aspect is most important for one simple reason: This is just the beginning and we haven’t really seen anything yet. Perhaps the biggest question for the various counter drone companies out there is this: what can you seriously do if a malicious, determined and technologically savvy operator with custom gear decides today is their day?

Malek Murison