Long before stories of Unmanned Aircraft Systems (UAS), or “drones,” appeared frequently in the news, NASA and the Federal Aviation Administration (FAA) recognized the need to safely manage UAS flying at low altitudes in airspace not currently managed by the FAA. For more than 25 years, NASA has conducted air traffic management system research in partnership with the FAA, providing a variety of computer-based tools that help maintain safety in increasingly crowded skies.“The sky could become increasingly crowded as personal and commercial uses of unmanned aircraft systems (UAS) become more popular,” said Parimal Kopardekar, manager of NASA’s Safe Autonomous Systems Operations project, as innovators constantly conceive new beneficial civilian applications for these aircraft, including goods delivery, infrastructure inspection, search and rescue, and agricultural monitoring.Last year, NASA’s Ames Research Center in Moffett Field, CA, released an open call to invite government, industry, and academic partners to collaborate with NASA to conduct and identify research needs, and to accelerate the development of a UAS management system. Around the same time, several major technology companies, such as Amazon and Google, announced plans to launch their own UAS applications. However, before these and any other commercial efforts took flight, a safety system had to be in place to make sure the new unmanned aircraft didn’t collide into buildings, airplanes, or each other.