The traffic volume of unmanned aircraft systems (UAS) is expected to grow significantly over the coming decade. The European U-space regulation draft defines in abstract terms how UAS traffic will be managed in future. Naturally, the draft omits compliance and implementation details, which are left to working groups at EASA and various standardization bodies. In this paper, we provide an overview of challenges that need to be solved before a UAS traffic management (UTM) that is compliant with the regulation may become operational. Furthermore, we present initial solution approaches with regard to airspace design and deconfliction. Our results are based on experience in implementing a prototypical UTM for the city of Hamburg, Germany, an urban environment in controlled airspace. However, many of our results are applicable to other environments as well.