In this paper, we show that qualitative comparative analysis (QCA) is well suited to studying complex phenomena. We focus here on the supposed correlation between the organization of air traffic control services and the trend towards commercialization orientation of the suppliers of these services. A simple statistical analysis (regression) seems to confirm this correlation, which has been suggested by the European Commission. However, if we use QCA on the same data, we can go beyond this general trend and demonstrate that a large variety of different models are possible. QCA also demonstrates that there are no simple laws that explain the results.