GATWICK. Heathrow. Newark. Dubai. Dublin. In the past four months, airports have been brought to a standstill by the sight of drones hovering above runways. Last week, rules came into force in the UK that make it illegal to fly drones within 5 kilometres of an airport. But is there anything more we can do to stop them becoming a weaponised nuisance?
The drone sightings all resulted in the immediate grounding of flights due to fears that a collision could cause a commercial aircraft to crash. “These really high-profile incidents have brought to light not only the threat posed by drones, but the difficulty in countering them effectively,” says Arthur Holland Michel at the Center for the Study of the Drone at Bard College, New York.
Most of the incidents lasted less than an hour. But given that flights at major airports take off or land so frequently – every 45 seconds at Heathrow in west London – even grounding planes for a short spell has considerable consequences. When passengers, crews and aircraft end up in the wrong place, it can take weeks to rectify.
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As a result, waiting for nuisance drone operators to get bored and fly off isn’t an option. Airports must be able to take active measures to prevent drones from ever reaching their airspace, or grounding them if they manage to slip through undetected.
“Anti-drone technology is a massive growth area and countries around the world are interested in it,” says Ulrike Franke, who studies drones at the European Council on Foreign Relations.
The US Department of Defense is spending hundreds of millions of dollars on research and development for counter-drone systems, says Michel, while a slew of companies are selling anti-drone technology – more than 155 firms in 33 nations, according to a . Around a third of these systems can both detect and attack drones, with the remainder roughly equally split between doing one or the other.
“These incidents expose both the threat posed by drones and the difficulty in countering them”
Signal jamming is the most popular way to stop a drone in mid-flight: about 100 anti-drone systems on sale disrupt either the radio frequency (RF) link between the drone and its operator, or the drone’s GPS connection, causing it to land in place or return to its take-off point.
“In order to disrupt an RF signal, you transmit more energy on that frequency,” says Jonathan Aitken at the University of Sheffield, UK. “If it’s overpowered, you lose the link between the controller and the drone.”
A defence system developed by UK-based Chess Dynamics uses this method and was installed at Gatwick, near London, after its trouble with drones, . And Ronald Reagan Washington National Airport near Washington DC jams RF signals in a 55-kilometre radius around its airspace. Portable jammers are also available. A gun developed by Australian firm DroneShield held in that country.
Shoot them down
RF jamming is not without issues, however. It would be incredibly disruptive in tourist hotspots, for example. “You don’t want to jam all Wi-Fi or mobile phone signals in a 1-kilometre radius around Buckingham Palace,” says Franke. Even at airports, it can cause problems. “We have sensitive equipment on an airfield,” says Aitken. “Putting a high-powered RF beam into that environment may damage other antennas.”
GPS jamming is also not guaranteed to bring down a drone. After a series of drone attacks by Islamic State in Iraq in early 2017 (see “Malicious drone use”), coalition forces asked drone manufacturer DJI to geofence the city of Mosul by updating the app used to control its drones, preventing GPS use and enforcing a no-fly zone. The terrorists simply switched off the GPS. While most autonomous drones rely on satellite navigation, skilled pilots can fly without the technology.
Away from war zones, exasperated holiday-makers experiencing disruption often call for drones to just be shot down, but this isn’t really workable, especially in populated areas. “Drones are very cheap and air-defence systems are very expensive,” says Michel. Even bullets are dangerous, as anything fired into the air will eventually come down at lethal speed.
This means such radical action is only really acceptable in life-or-death situations. “There are many things you can do in a military environment that you can’t do in a civilian environment,” says Franke. Costs aside, the risk that a misfire could prove deadly meant the British police were loathe to shoot down the Gatwick and Heathrow drones either side of Christmas 2018.
Then there are the more wacky ideas. Numerous police forces have tried and failed to train eagles to snatch drones out of the air, while police in Tokyo, Japan, have a squadron of interceptor drones that fire a net with an attached parachute that can take a target drone out of the sky. Similar technology was also used at the South Korean Winter Olympics in 2018.
Before you even think about taking a drone out of the air, you need to find it. “There are lots of birds in the sky,” says Franke. “And birds aren’t that different from drones.” They’re both relatively small, travel slowly and existing radar systems aren’t calibrated to detect them. Cameras also struggle to discern between drones that are close and aircraft that are far away.
Still, new ideas for drone detection are being developed. In the UK, Cranfield University is working on a system that will use 4G and 5G mobile connections to provide real-time detection, and is testing it on a private air corridor near the university’s airport. However, there is little to stop those wanting to shake off detection simply disabling 4G and 5G capabilities on their drone before flying.
Opinions are split as to whether anti-drone technology has a bright future. “I’d like to come up with an easy answer, saying there are lots of people researching it and we’ve got one nice solution that’s going to fit, but there’s not one,” says Aitken.
“You don’t want to jam all phone signals in a 1-kilometre radius around Buckingham Palace”
However, the sheer weight of ongoing research means a solution is likely to come soon, says Franke. “A lot of different technologies are being developed, and I think in the next few years we’re going to have some kind of anti-drone technology installed around airports, prisons and other important areas.”
She forecasts that portable technology – anti-drone rifles that can direct an RF beam to overcome a single drone, for instance – will become more commonplace, while systems that combine multiple methods of detecting and stopping drones will become more popular and effective.
But it might take something entirely new, says Michel. “People are waiting for that silver bullet, that new paradigm,” he says. “We’re hoping there’s a teenager in a basement somewhere concocting a new machine that’s putting the final nail into the coffin of drone attacks.”
Malicious drone use
In recent years, consumer drones have disrupted airports and been used for weaponised attacks
25 February 2017
In a video, Islamic State claims to have carried out a drone-based attack in Mosul, Iraq, by dropping a warhead from an off-the-shelf drone – although some experts say the footage appears to be fake. The terrorist group uses a similar method to destroy an arms depot in Syria the following October.
4 August 2018
Venezuelan president Nicolás Maduro survives an assassination attempt while giving a speech in Caracas. Two drones carrying explosives were used in an apparent effort to kill him: one manages to hover close to Maduro and detonate its payload, while the other explodes two blocks away.
19-21 December 2018
More than 140,000 passengers and over 1000 flights are affected by drone sightings at Gatwick Airport, near London. More than 100 sightings were reported over three days, according to police, who believe an airport employee may have been behind the chaos.
21 February 2019
In the latest incident of drone-based disruption, flights are suspended at Dublin Airport in Ireland after a “confirmed sighting of a drone”. Travel into and out of the airport resumes after half an hour, but not before three flights are diverted to nearby airports.
