This research investigates the use of Solution Space Diagram (SSD) as a measure of sector complexity and also as a predictor of performance and workload, focusing on the scenarios regarding Air Traffic Controller (ATCO)’s ability to detect future conflicts. A human-in-the-loop experiment with varying intercept angle within the same sector layout has been designed and conducted. A short duration and a single predetermined conflict for each scenario were programmed to ensure a controlled experiment environment. The main aim of this experiment is to investigate whether the SSD can predict the workload ratings and subject performance in a conflict detection task. Based on the results, no common pattern can be observed, which can directly associate workload ratings and SSD area properties for various intercept angles. As conflict presented in the experiment between the converging aircraft, it was found that smaller SSD observation angles correlate better with the workload rating. These results were anticipated, as in converging conditions aircraft ahead of the velocity vector will be captured as the main focus. The SSD also does not represent a trigger for conflict detection. There is no consistent SSD area percentage where ATCO would start detecting conflict. Thus, it is concluded that the SSD does not represent a trigger for conflict detection.