Airport Drone Mitigation
Part 5: When a Drone is Jammed…

In the previous post – Drone Jamming Effectiveness at Airports – we discussed the effectiveness, features, and limitations of jammers. Specifically, we looked at what happens to a drone when it’s jammed, and how that can affect airport activities.

Let’s go a bit further to understand what a drone recovery program is and its fundamental issues. What a drone will do when it’s jammed depends on who programmed it, and how it was done.

Deaf and Blind

When a drone is effectively jammed, the drone pilot’s signal commands and/or the GPS signal cannot be received and understood by the drone because of the intense noise interference created by the RF jammer – it’s blocked out. Essentially, the drone is now flying ‘deaf’ because the communications link between the drone pilot’s transmitter and the drone’s receiver has been temporarily severed, or the drone is flying ‘blind’ because the GPS signal is not received as it is blocked out.

Commercial Drones

For most commercial drones, when it loses communication with the pilot, the drone is pre-programmed by the manufacturer to immediately enter hover mode, so it doesn’t hit anything. It will then climb vertically to a safe altitude so it’s clear of any obstacles, then execute a return to home – either where it originally took off from or an updated home location. Some drones will simply land where they are if the programming deems it to be safer to do so (for example, if GPS isn’t available to them and navigation can’t be trusted). If the drone is low on battery power and is unable to make it to the home location, or the return track is deemed too risky, it is usually programmed to go into hover mode and land, or begin its journey home before descending vertically with only sufficient battery power to complete a controlled ‘soft’ landing. All this is without any input from the pilot.

Among the different manufacturers and different models, there are variations of this programmed flight, but it’s essentially a program to return the drone, or to keep the drone safe.

DIY Drones and Hacked Commercial Drones

Most DIY drone enthusiasts will also want to keep their drone safe from harm and be able to return them  home, so the process above is likely to be the same. They may have a more complex program, with multiple safe landing points along a route, especially when working near the edge of the flight endurance envelope. However, a sinister pilot who may want to hit a planned target like a crowd, building or aircraft on the ground, or has attached an Improvised Explosive Device (IED) or chemical aerosol spray to the drone, could reprogram their commercial or DIY drone with a ‘home location’ which is exactly the same location as the ‘target location’!

Crash, Bang, Wallop

Even if you can positively identify the exact make and model of the drone, it’s still not possible to know exactly what it will do when it’s jammed due to many factors:

• Firmware and Software – The firmware and software in the drone are constantly being updated and with it, the program it follows when it loses connectivity with the pilot. As we highlighted before, when jammed, it might land immediately, it might attempt to return home on a reverse route, it might return taking the shortest route to home (which might be straight across a runway, flight path, crowd or into a building, such as an air traffic control tower), or it might return as close to home as possible and land.
• Hacked Drones – The programmer may follow one of the safer programs as referred to above, but may also have programmed the drone with sinister intent. When jammed, it may be programmed to fly directly into a target, or to hover for as long as the battery lasts before crashing. It could perhaps land in a location which causes an obstruction or even mimic that it’s landed and been defeated, before taking off again. It may be programmed to fly a set flight pattern for maximum annoyance so it’s difficult to jam. It might even be programmed to fly away from the airfield to avoid jamming before returning from a different direction each time. The possibilities are as endless as the creativity of the person who programs the drone.
• Unpredictability and Instability – Drones do not always behave as they’re programmed when that amount of energy is fired at them from an RF jammer. Many drones can become unpredictable or unstable and when this occurs things can get out of control very quickly. The drone may lose control and crash where it is or somewhere else in the near vicinity. It may hover until the power fails and crash. The drone may become completely disorientated and attempt to return home, but instead fly a different fight profile crashing elsewhere.

Stop, Stop, Stop ….

When a drone responds to jamming in a way that the operator doesn’t expect, there is little that the jammer operator can do, other than to stop jamming. Having spoken to many jammer operators, I understand that they expect one of these four things to happen:

• the drone will respond unpredictably, resulting in a crash or further issues.
• the drone descends and lands.
• the drone executes its recovery program.
• the drone moves out of jammer range and control reverts back to the drone pilot, who may continue with the initial intent.

Given all the issues regarding jamming operations near airports, airport security and police must decide if jamming is the right solution for them, and whether they should purchase a jamming system or look at alternatives to mitigate the threat from a rogue drone.

In my next blog post, we will look at key questions on whether Jamming is a Viable Solution for Airports.