UAS in civil airspace: Demonstrating "sense and avoid" capabilities in flight trials

The mission spectrum of future UAS (unmanned arial system) will require its integration into civil airspace. Among all technologies and procedures that are currently discussed and developed to enable UAS operations in civil controlled airspace, collision avoidance is emerging as a key issue for UAS access to civil airspace. This paper reports about the Sense & Avoid research activities that have been carried out in the frame of the German WASLA-HALE project. Algorithms for sense and avoid have been developed and tested in both simulated scenarios and real flight trials. For the flight trials, DLRpsilas test aircraft ATTAS equipped with a radar sensor served as a UAV demonstrator, and a two other DLR test aircraft, a Dornier Do 228 and a DR-400 served as intruders to the ATTAS aircraft. In the first flight trials, all data coming from the radar sensor have been recorded and processed offline. The developed algorithms showed very promising results. The real target could have been separated form ghost targets, the trajectory of the intruder was predicted with sufficient accuracy and the avoidance algorithm gave correct avoidance advisories. The second flight campaign successfully demonstrated autonomous avoid manoeuvres based on the described sense and avoid algorithms.