The digitalization of business processes implies important changes in the organization of air traffic control companies. In this research, we have developed an original critical incident drill approach based on service design techniques combined with risk management. The aim is to take into account the co-production elements inherent to any complex service system and also the necessary interplay between explicit (information) and tacit (know-how) knowledge. The critical incident drill begins with a preparation where immersion episodes and modeling of new digital processes by the service blueprint allows to imagine coherent and coordinated interactions between human expertise, information system and any external IT provider. Once ready the new process is simulated in real size and conditions. Co-creation between stakeholders makes it possible to conduct a relevant analysis of the risks as well as opportunities for improvement. This approach has been used successfully by skyguide to test and implement new air traffic management digitalized processes.