Introduction

The US and Europe are paving the way for the integration of unmanned aerial vehicles (UAVs) into civil airspace. Some commentators suggest that commercial cargo UAVs will be flying through the skies in the next 5 years. While there is now considerable momentum in the expansion of this industry in the civil arena, a number of aspects must still be addressed in order to satisfy the regulators, insurers and the general public about the use of drones in civil airspace. It is, however, no longer a question of “if”, but “when”.

The use of UAVs in a military context is well established and documented, but their use is confined to segregated airspace. Equally the use of small UAVs, such as for agricultural, search and rescue or survey operations, is in low airspace and limited. The challenge faced now is to enable UAVs to share non-segregated airspace with other, manned, aircraft.

Safety is the overriding principle in enabling this integration. This article looks at some of the developments in this area.

Technology

The performance of UAVs is ever improving as is the technology looking at the safety of UAV flight. For a UAV flight, like that for an aircraft, there are three main interfaces1 - between the pilot and UAV, between the UAV and air traffic control, and between the UAV and other air traffic.

It will be some time before UAVs are fully autonomous and therefore the reliability and safety of the data-link and controls between a UAV and the pilot, who is on the ground and potentially miles away, are of paramount importance.

In 2012, a group of University of Texas students took control of a US military UAV by hacking into its communication system in response to a dare from the US Department of Homeland Security. The potential risk to the UAV’s safe navigation and control means this is a real focus to ensure public confidence in the technology.

Secure communication is one of the aspects of UAV flight for which ASTREA, a partnership of UK government departments, aviation industry partners and academic institutions, has been looking to find solutions. ASTREA has developed a project using airborne Internet Protocol (IP) architecture, whereby the communication signal is sent through multiple stops, instead of one (known as multi-hop data routing), while maintaining end-to-end security.

The reliability and security of the necessary communication channels will be crucial for any integration of UAVs into non-segregated airspace and to convince the general public, insurers and the regulators that it is safe.

The use of UAVs in a civil commercial context is currently for small UAVs used for tele-observation activities, such as disaster response, search and rescue operations, pipeline monitoring and security activities for the petrochemical industry. There is also a focus on making such systems as small and light as possible. A further technological focus is on collision avoidance systems. As has been documented in the press, there have been mid-air collisions involving military UAVs. For obvious reasons the development of sophisticated and robust “sense-and-avoid” systems has been a key focus for the civil UAV sector. (Sense-and-avoid systems are collision warning and avoidance systems that use either electro-optical cameras, laser radar devices or transponders.)

ADS-B (automatic dependent surveillance-broadcast) transponders broadcast the aircraft’s location in real time and deliver information on altitude and velocity, but also provide the UAV itself with data on other aircraft in the sky, weather and terrain. This type of transponder will be a Federal Aviation Administration (FAA) requirement for most aircraft operating in US airspace from January 2020.

There are a number of companies and groupings working on the development of “sense-and-avoid” systems, including ASTREA. A combined effort by five European countries (Sweden, Germany, France, Italy and Spain) and 11 industrial parties are developing the “Mid-Air Collision Avoidance System” (MIDCAS), which integrates ADS-B with electro-optical cameras and an infrared camera to identify other aircraft.

The large number of companies involved, particularly in the US and Europe, in developing the technologies for the safe integration of commercial UAVs means that it should not be long until that technology is fully ready. It then is a question of regulatory approval.

Regulatory

In order to fly in non-segregated airspace commercial UAVs will need to meet the same level of airworthiness as manned aircraft and obtain the appropriate certification. In addition, each of the elements and technology that make a UAV “unmanned”, such as the “sense-and-avoid” system, will require its own airworthiness certification. This is where the regulator and industry will need to work closely together.

ASTREA, for example, addressed the regulatory aspects through a “Virtual Certification” programme together with the Civil Aviation Authority for the certification of systems unique to UAVs. It applied this programme to be able to carry out a remotely piloted flight of a Jetstream 31 aircraft through UK airspace at the beginning of last year.

The FAA Modernization and Reform Act was passed by US Congress on 14 February 2012. It sets a deadline for the FAA to “allow the safe integration” of UAVs into US national airspace by 30 September 2015 - a date not that far away. As part of this drive the FAA recently announced the six public entities selected to develop unmanned aircraft systems (UAS) research and test sites around the country.

Europe is not far behind. The EU set up a UAS initiative in 2011 and launched a study on the integration of UAVs as part of the Single European Sky initiative. A final report from the European Remotely Piloted Aircraft System Steering Group on the integration of UAVs into European airspace was presented to the European Commission in June 2013, with a view to integration starting in 2016.

Conclusion

It is clear that the integration of UAVs into non-segregated airspace requires a high level of collaboration between those in the UAV industry and aviation regulatory bodies, partly because it is such a new technology. In an industry renowned for its robust safety culture, integration may not come as soon as some predict, since the regulators will need to be satisfied of the safety of the technology. Nevertheless, the not too distant future of civil aviation will be both “manned” and “unmanned”.