The growth in drone use has caused an upsurge in near-miss reports and increased the risk of drones disrupting or even colliding with air traffic.
Consumer and commercial drones typically weigh under 10kg and mostly less than 2kg. Quadcopters with four horizontal rotor blades are most common but there are also small fixed-wing drones.
Drones are able to stay in the air for up to 30mins at a time, with quick battery changes and/or multiple drones able to cause persistent disruption. Regulations notwithstanding, drones are certainly capable of flight up to 6000m altitude and up to 8km from their operator and controller, which easily brings them into the same airspace as passenger aircraft approaching or taking-off at airports.
Studies have shown that a drone collision with an aircraft is more damaging than an equivalent energy bird strike, and that drones colliding with aircraft can damage the structure to cause a crash.
Besides the unintentional disruption or collisions caused by drone operators who either don’t know, or choose to ignore, drone safety regulations around airports, there is another risk. From those who intentionally choose to cause disruption.
Consumer drones are capable of lifting small payloads of 500g and commercial drones can carry upwards of 6kg. If a terrorist wants to blow up a passenger plane, delivering the explosives by drone is probably more likely than through airport security on the ground.
There are different technologies available for both monitoring and countering-drones. Monitoring is allowed and recommended. Neutralising drones is still (in most countries) not legally permitted.
Typical monitoring technologies include Radio Frequency (RF) Analysers, Acoustic Systems, Cameras, and Radar. Each has their individual pros and cons and it is recommended that systems purchased for airport drone monitoring are an integration of:
• RF, for identification and triangulation of both drone and controller (if radio signals present);
• Cameras, for visual identification and understanding of threat and intent; and
• Radar, for long range detection, accurate localisation and tracking (also from drone swarms), and drone classification even from autonomous drones not sending any radio signals.
When using radar for drone detection, be it stand-alone or part of an integrated system, it should be micro-doppler radar. Specially designed micro-doppler radars are available that can differentiate birds from drones. This avoids drone alarms caused by birds; a common issue with radar.
Typical countermeasure technologies include, RF Jammers, GPS Spoofers, High Power Microwave (HPM) Devices, Nets and Net Guns, High Energy Lasers, and Birds of Prey. None are allowed due to regulations, but should an exemption be approved, Net Guns have a low collateral damage risk at an airport.
RF jamming, GPS spoofing and Electromagnetic Pulses (EMPs) generated by HPM Devices have an increased electronic collateral damage risk at airports but could be used successfully if coordinated and managed correctly.