HEMS BVLOS Drone with FLARM-based Detect & Avoid

Swiss HEMS-operator Rega presented a new type of aircraft for searching for missing persons: the newly developed Rega drone can autonomously scan large search areas and is equipped with various sensors, such as a thermal camera. As a result, in future, Rega will have at its disposal an additional device to help it search for people in distress if the helicopter has to remain on the ground due to poor visibility.

“We observed the development of drone technology from an early stage and were always convinced that drones could be of help in particular on search missions,” says Head of Helicopter Operations Sascha Hardegger. However, there is currently no drone system on the market that meets all of Rega’s requirements. In particular, it is not possible to operate a relatively small, lightweight and flexible drone over a distance of several kilometres and for several hours without visual contact with the drone pilot. “As a result, we took the initiative and decided to develop a Rega drone ourselves in collaboration with suitable partners”.

With its three rotor blades, a rotor diameter of just over two metres and 10 kg payload, the new Rega drone looks like a mini helicopter. During a search mission, it scans large search areas precisely and autonomously (16 km2 in 2 hours with 80 km/h). It is able to independently detect and avoid other aircraft or obstacles, such as helicopters and overhead cables. This is possible thanks to anti-collision systems, coupled with countless data stored in the drone’s in-flight computer, such as digital models of the terrain and obstacle databases. The drone operates without visual contact with the pilot (BVLOS), has an endurance of 3 hours and maximal speed of 120 km/h.

With two redundant GNSS receivers, the Rega drone flies autonomously on a predefined route. It follows the topography of the terrain at an altitude of around 80–100 metres above ground level. In addition, a ground radar is built into the drone. Like many aircraft in Switzerland, the drone is equipped with the FLARM anti-collision system. The FLARM signals are evaluated on board. If necessary, the drone will automatically alter its flight path in order to avoid an impending collision.

Thanks to the FLARM anti-collision warning system, the drone is mutually recognisable electronically by other aircraft from a considerable distance. The drone pilot at the ground control station is constantly connected with the so-called U-space. This is an air traffic management system that is currently being set up to coordinate unmanned aircraft in jointly used airspace. It aims to prevent the drone from getting dangerously close to known air traffic.

For the event that, despite all the precautions described above, the Rega drone does get dangerously close to an aircraft and runs the risk of colliding with it, it is equipped with an active, automatic anticollision function (detect & avoid, DAA). Based on the signals transmitted by the FLARM anti-collision warning system, the drone autonomously alters its flight path in good time to avoid colliding with the other aircraft. Around 80 percent of all aircraft in Switzerland, including all of Rega’s helicopters, are voluntarily equipped with FLARM, and the system is also becoming increasingly popular with paraglider pilots. This collision avoidance function will soon be enhanced with a built-in radar device to avoid non-cooperative traffic.