Hard to catch and hard to kill. The chaos at Gatwick airport highlights the security threat posed by drones and the challenges that authorities face in guarding against them.
Drone incidents at airports are on the rise and pilots fear it's just a question of time before disaster strikes.
"We invested in some research last year with the Department of Transport and the Military Aviation Authority, which proved that these drones, which only weigh two kilograms, but they have batteries and motors, if they hit an aircraft at the right speed, they can go through the windscreen, they can hit a tail rotor of a helicopter, they can cause catastrophic accidents," said pilot Dave Smith and British Airline Pilots’ Association (BALPA) representative
As a potential weapon of disruption, drones are relatively small and highly mobile. Their operators an elusive enemy. That makes it especially difficult for security forces to deal with them.
As one expert told Euronews, in built up urban areas, the possible responses are few: "We're talking of a drone something of the size of a dinner plate, moving at speed, highly maneuverable and therefore it makes it rather hard to actually shoot down with any kind of projectile, be it a bullet or whatever. We look at the major technology that's actually being used by the drone itself, which is the radio frequency that transmits the video and imagery from the drone to the controller. And that's where we've seen the most effective way of combating the encroachment of drones into airspace," he said.
A low tech approach has also been tried at Dutch airports, but using hunting birds has had limited success.
Security has always been a major challenge for aviation, but drone disruption is a new threat the authorities are struggling to cope with.