Working memory (WM) plays an important role in pilots since they have to continuously integrate and dynamically update information within a rapidly changing environment (Verdière, Roy & Dehais, 2018). WM is essential for overcoming response conflict and optimal selective attention performance. Yet, WM is a capacity-limited system, and some authors suggested that increasing the demands on WM reduces the ability to ignore irrelevant stimuli and can lead to decreased performance in dual– tasking (Lavie & Cox, 1997). Conversely, Simon et al. (2016) suggested that increased WM load is associated with enhanced protection from distraction. The heterogeneity of behavioural paradigms used makes it difficult to discern our understanding of the effect of task difficulty on brain activity and behavioural performance, in the context of WM. To address the conflicting accounts, we aimed to setup a dual-task paradigm similar to the real-world as encountered when piloting a plane. A spatial N-Back task was built concurrently with an auditory detection task. Then, we examined how changes in task difficulty was modulating functional brain activation and effective connectivity (Sun et al., 2019) in some important brain areas involved in WM (i.e., the medial and dorsolateral prefrontal cortex, mPFC and dlPFC). We reasoned that WM-related activation and connectivity would vary in proportion to the task difficulty.