What happens when the radio connection to a drone is interrupted? How can drones fly autonomously even in congested traffic? These and other questions were addressed by the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) in the final phase of its City Air Traffic Management (City-ATM) project. The researchers focused on investigating traffic scenarios in which a large number of drones with varying equipment are operated jointly and without conflict in shared airspace. At the end of 2021, the final flight tests with several drones took place at the National Experimental Test Center for Unmanned Aircraft Systems in Cochstedt, where the researchers demonstrated the functionalities they had developed.