46 Technology focus | Uncrewed Aircraft System Traffic Management involved, and they must pick out airborne traffic from ground clutter, including moving cars. They also require precise location information to make sense of radar echoes. This is difficult on the ground and even more complex in the sky. To compensate, pilots, and even huge air traffic control radars, rely on cooperative aircraft to beam out their locations using onboard transponders. The onboard radar is the size of a paperback book and weighs less than 1 kg, and it has already been used on crewed aircraft and helicopters to detect non-cooperating traffic. The onboard processor calculates avoidance paths, meaning aircraft do not need a separate computer to do this work. Two quadcopter UAVs flew at each other, 300 ft above the ground, at a test site in the desert. The UAV detected the ‘intruder’ and evaluated its flight path. Then it calculated an avoidance manoeuvre and took over the navigation to fly left, right, up, down or stop in midair, depending on winds and other factors. Once the danger of a collision had passed, the radar released control of the drone and the autopilot guided it back to its original course, all automatically. The team then challenged the radar with increasingly difficult encounters, such as approaching from below to blend into ground clutter and from offset angles, testing the radar’s peripheral vision and high, angular detection capabilities. In other flights, the team instructed the radar to wait longer before acting, forcing it to make more aggressive manoeuvres. The radar has a range of 3 km using a monopulse technology with a system of overlapping beams to increase accuracy and eliminate ground clutter. The radar steers its beams electronically, so it has no moving parts. Approval services An alternative UTM approach, especially around controlled airspace such as an airport, is an Approval Service platform. This allows UAV operators – and, in future, eVTOL pilots – to request and pay for operations within an airport’s airspace digitally at the touch of a button. The Approval Services platform links to flight-planning software without having to contact an airport, airfield or aerodrome to seek approval, and allows delivery services to operate in areas that otherwise would be difficult. By seeking a green light through Approval Services, UAV operators can get flights approved within minutes whereas previously it may have taken weeks. However, making airspace managers pay to configure and impose an administrative fee for reviewing and approving flight requests, where appropriate, is not necessarily popular as it is viewed as contradicting guidance that says UAV operators cannot be charged for access to airspace. In the UK, the CAP 722C guidance provides policy and advice to sponsors of airspace and UAS operators, while the regulations for airspace sponsors and UAS operators can be found in UAS Regulation (EU) 2019/947. Additional platform services are becoming necessary because the amount of information being handled by airspace managers is increasing rapidly. An Approval Services platform enables an airspace manager to understand and manage airspace in a safer, more controlled way, with UAV operation marked clearly on a map and the operator’s details to hand. Japan has developed a UAV traffic management system for multiple operators in the same airspace. The project, named Drones and Robots for Ecologically Sustainable Societies (DRESS) brings together 29 partners, including private companies and research institutions. In the DRESS project, the UTM system includes a simulator, whereby the traffic management of numerous UAV flights can be simulated. The UTM helps multiple UAVs to fly more freely beyond visual line of sight within the same airspace. Testing at the Fukushima Robot Test Field in Minamisoma, a city in Fukushima Prefecture, connected 29 UAS operators via the UTM system and flew 46 drones in a shared airspace of 1 km2, completing a total of 146 flights within one hour. During the test, the UAS operators used the UTM system to obtain information about the geography, climate and airspace, with flight-restricted areas. The operators also shared information on their flight plan (planned flight route or area) and real-time flight status (actual August/September 2024 | Uncrewed Systems Technology An approval service can ease access to airspace for UAV operators (Image courtesy of Altitude Angel)
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