Until now, army drones fly in segregated airspace, but soon they will also be allowed for civil airspace. For this purpose, military companies are developing automatic avoid systems. The “Eurodrone” will be the first to implement this as standard; in Germany, the “Triton” spy drone may be faster.

The European defence companies Airbus, Dassault and Leonardo want to develop the armed “Eurodrone” to production readiness by 2025. The medium-altitude-long-endurance drone (MALE) should then be flown by the Bundeswehr and other armies of the EU. In Germany, military drones have so far been operating exclusively in specially reserved airspaces. That could change soon: The Eurodrone is to be fully integrated into the so-called controlled airspace.

According to the plans, the unmanned aeroplane would then be placed on an equal footing with civil aviation and would also be subject to the control of civil air traffic controllers. However, a prerequisite for flying in civil airspace is the installation of a functional evasion system (See and Avoid, SAA or Detect and Avoid, DAA). The drones are to react to impending collisions in the air and initiate automatic flight maneuvers.

So far only manual evasive manoeuvres

According to the German federal government, there is currently no reliable or even certified SAA system. However, to avoid collisions is necessary so that the drones can be controlled beyond line of sight via satellite. The arms companies Thales and Leonardo have carried out such a test flight, which is unique in Europe, as part of an EU project.

Conventional drones such as the “Heron TP” ordered by the Bundeswehr only have a warning system for possible collisions (Traffic Alert and Collision Avoidance System, TCAS). In the case of the “Heron”, the TCAS gives vertical evasion recommendations, the drone can then change into ascent or descent. However, the manoeuvre must be initiated by the pilots of the drone.

Warnings also come from a weather radar, which will also be installed in the Heron of the German Armed Forces to detect thunderstorm cells. In addition, Heron sends position and other flight data via a transponder (Automatic Dependent Surveillance – Broadcast System, ADS-B), including speed, altitude and course. The data are received and processed by civilian flight control. Web pages for tracking aircraft movements also use the transponder data.

Ministry of Defense commissions research

For the use of military drones (also for civilian applications) the development of an automatic avoid system is of decisive importance. The Federal Ministry of Defence (BMVg) has therefore commissioned “experimental investigations” to close these “technology gaps”. This is not about the development of a complete SAA system, but about the investigation of its “core elements”.
Logo of the project “Enhanced Remotely Piloted Aircraft System Autonomy” led by the German BMVg. All rights reserved FDFA

At EU level, the Ministry of Defence is researching a “Mid-air Collision Avoidance System” (MIDCAS) with military personnel from France, Italy, Sweden and Spain. The aim is to develop a standardised European procedure for evasive manoeuvres of unmanned aerial vehicles. The German defence companies Airbus, Diehl BGT Defence and ESG Elektroniksystem- und Logistik GmbH are participating in the project of the European Defence Agency (EDA). The German Aerospace Center is also part of the consortium. The EDA is also working on the standardisation of sensors for the automatic determination of the distance of other aircraft.

In another EDA project “Enhanced Remotely Piloted Aircraft System Autonomy”, the German Ministry of Defence, as project leader, is investigating technologies for automatic take-offs and landings, so-called taxiing on the way to the tarmac, and automatic emergency landing procedures. The drones are to be integrated into the processes of civil air traffic controllers. Here too, Airbus and ESG are involved. It is planned that the German “Heron” drones will also receive such an “autonomous take-off and landing system”. It is based on GPS position data and an integrated radar-based system serves as an emergency landing system.

German giant drones with evasion system

Finally, the European Defence Agency has commissioned a study to assess the air safety of drones. The British military company Thales and the Dutch space institute NLR have investigated the automated and semi-automated processes necessary for integration into European airspace.

According to its own statements, the NLR has already developed a reliable evasion system for helicopter drones of the Austrian manufacturer Schiebel. The Israeli Elbit group intends to develop a collision avoidance technology for the military drones ordered by Switzerland by 2021. The Israeli manufacturer of the “Heron” drones is also working with the US company Honeywell on such a process, but it is not ready for use. According to media reports, Honeywell’s cooperation with the US manufacturer of “Predator” drones is much more advanced.

By 2023, the US drones “Triton” are also to receive the “ACAS Xu” avoid system developed on behalf of NASA. The Bundeswehr wants to buy three of these “Triton” and equip them with espionage technology from Airbus. According to the Federal Ministry of Defence, the development of the “ACAS Xu”, which is already being tested, is “very advanced” and could be available from 2020. The “exact technical design” of the alternative system for the German “Triton” will now be coordinated by the Ministry with the US Navy and the responsible US authorities. It is therefore quite possible that the giant drones will be operating in German civil airspace in a few years.

Image: Non-airworthy model of the ILA in Berlin (all rights reserved Airbus).