The threat of rogue drones and how to stop them

The popularity and widespread availability of drones is causing concern for airports, military bases, power stations, and other sensitive areas. As well as the risk of a drone causing a fatal accident with a manned aircraft, they can also be a tool for spying and intelligence gathering. Drones are being used to smuggle drugs and cell phones into prisons, and there are fears terrorists could use one to carry explosives or weapons. These threats have led to the development of counter-drone technology.

Changes in the laws governing the use of unmanned aircraft is one solution to the problem of mis-use, but there will always be those who will act irresponsibly and ignore legislation. In December 2018, London’s Gatwick Airport was closed for nearly two days following numerous sightings of drones around the runway. Two local people were eventually arrested, but later released without charges. This incident highlighted the problem and prompted other airports to review their policies for dealing with drone activity.

There has been some debate as to whether a drone could bring down a large aircraft in the event of a collision. Up until recently, bird strikes were one of the greatest threats to manned aircraft. There have been cases where birds have caused serious harm to jet engines, and a drone made of metal and plastic could inflict more damage than feathers and bones. A drone is unlikely to reach the altitudes passenger aircraft fly at, but there is a risk around airports during take off and landing.

Tests of counter-drone technology by the US government in recent years have cast doubts on whether the systems currently available are effective. Radar systems designed to identify and track small unmanned aircraft are unreliable when drones hover in place. The high volume of radio broadcasts in the vicinity of airports can make drone transmissions hard to pinpoint, and stronger signals can mask their presence. False sightings are a common problem, and these can lead to unnecessary airport closures and disruption.

Grabbing a shotgun to take down a trespassing drone may sound like an easy answer, but it’s not safe or legal. The Battelle Corporation has developed a more sophisticated solution for shooting down a drone with a device firing concentrated energy to disrupt GPS reception and remote control signal rather than bullets.

An English start-up company, Open Works Engineering, has developed a shoulder-mounted net cannon as a way to bring down rogue drones. A sophisticated tracking system locks on to the drone before firing a capsule containing the net. The built-in parachute ensures that the captured aircraft is brought back to the ground slowly to minimise the risk of damage to people and property in the vicinity. The net cannon can be reloaded in less than ten seconds, allowing it deal with several drones at a time. Nets can also be fired from drones, and some systems allow a rogue aircraft to be captured so it can be examined.

Technology isn’t the only counter-drone option, and birds of prey have been trained to take down unmanned aircraft in the Netherlands. Law enforcement agents are using eagles to pluck drones from the air if they’re flown where they shouldn’t be.

Drone use is projected to escalate rapidly over the next decade, and this will mean governments, private companies, and the military will need to develop solutions to combat rogue operators. Effective measures to protect sensitive locations and minimize the risk of collisions involve a combination of drone detection systems and tools to remove them from the air. Unmanned aircraft can bring many benefits, but it’s essential that air safety is maintained.