Just before Christmas 2018, there was significant interruption and delay when a drone was spotted at Gatwick Airport. As well as causing a lot of frustration for air operators and travellers, the incident initiated discussions among the general public and within the industry, much of which deserves closer scrutiny to avoid potentially dangerous decision-making in response to similar future events.

What has the aviation industry put in place?

For some time the aviation industry has been warning about the dangers posed by drones and the disruption they are capable of causing. Close encounters of aircraft with drones have occurred for a number of years now, from a handful of sightings in 2015, to over 160 sightings last year in the UK alone.

Aviation has been pushing for stricter controls and laws covering the use of drones. The UK Government and Civil Aviation Authority, as in many other countries, not only drew up guidelines for manufacturers, but also sought to educate drone users by drawing up a set of rules for the safe operation of their drone.

If you own and use a drone, therefore, you can’t fly your drone above 400 feet and it must remain within sight of the operator or a responsible person acting as your lookout (this responsible person could be your best mate as long as he or she is over 18). This is unless you have a commercial licence to operate outside the rules, such as for film companies, surveyors, etc..

Why are drones dangerous? 

Birds have been colliding with planes since the time of the Wright Brothers. A bird causes a lot of damage to an aircraft on initial impact, but as the bones are hollow, birds don’t have much mass and come off a lot worse than the aircraft.

Drones, on the other hand, have solid metal parts like motors and gears and a solid battery as well. Therefore, a drone will cause at least as much damage on initial impact; but because a drone has mass, it also has inertia, which means it continues further inside the aircraft causing more catastrophic internal damage to the aircraft's internal structure rather than just the skin as a bird tends to do. This is why following a drone sighting, airports will close and not allow any traffic flow to prevent the possibility of an aircraft hitting a drone.

On the day in question, Gatwick had a report of a drone over the airport, so they put their drone plan into action and closed the airport. After a period of time there were no more sightings, so the airport prepared to open again. Then a drone reappeared and the whole process began again, with the delay lasting for 36 hours. It became apparent that the drone was being deliberately targeted at the airport to cause maximum disruption to operations.

Can’t we just shoot them down? 

It is possible to shoot down a drone, but only if it is close and static. But a relatively small target around 500 feet the air that's moving erratically would challenge any marksman. Furthermore, if the shot missed, the bullet or projectile would eventually fall to earth somewhere, and they can do as much damage coming down as they can going up.

What about jamming the signal? 

To some degree this method does work. The problem is that you first need to know the frequency used to control the drone must first be known. The alternative is to use a blanket frequency blocker that covers a wide range of frequencies, but, of course, the obvious problem to using ‘blockers’ is that this technology could well have an effect on other radio or electronic equipment. At an airport with aircraft navigation systems, radars, computers, and radios for ground and air communications, that could cause more problems than it solves.

What about Geo-fencing? 

Geo-fencing is more new technology and can be very effective. The programme comprises a small GPS system so the drone ‘knows’ where it is in space and it can be programmed to stop the drone being flown into areas where it shouldn’t be, like airports, prisons, nuclear facilities etc. But like most technology, Geo-fencing can be hacked and either modified or disabled. For someone intent on causing trouble hacking would be a relatively easy thing to do.

What about nets, trap drones - or eagles?

These are among the more novel ideas being suggested to counter the drone threat. They are, like the others, only effective to a degree and in very specific situations.

For now, drones pose a very real threat to aviation safety and the possibility of an aircraft being bought down by a drone is a reality. What is needed now is suitable, proportionate and effective legislation backed up by robust prosecutions and sentencing. In parallel to this we will have to keep developing the technologies that will restrict drones from flying where they shouldn’t be or, defences that can disable a rogue drone before it presents a serious danger.

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