Cognitive Work Analysis (CWA) is an appropriate approach in high-stakes domains, such as Air Traffic Management (ATM). It provides focus on human expert performance in regular as well as contingency situations. However, CWA is not suitable for the design of a first-of-a-kind system, since there is nothing to analyze before the start of the design process. In 2017, unmanned traffic management (UTM) for intense drone traffic in cities was such a system. Making things worse, the UTM system has to be in place before the traffic, since it provides basic safety. In this paper we present conceptual designing as a bootstrapping approach to CWA for UTM as a first-of-a-kind system.