BACKGROUND: Standard low-resolution electromagnetic tomography (sLORETA) was used to accurately detect EEG changes in mental fatigue of air traffic controllers (ATCo) under a simulated air traffic control (ATC) task. We explored the changes in standard current density, activated cortical intensity, and brain source location. METHODS: The participants were instructed to use the tower flight command simulation training system for three hours of uninterrupted ATC task. The 3-hour EEG signal was divided into four stages: task start, 1st hour, 2nd hour, and task end. Each stage was preprocessed for 3 minutes to explore the EEG changes and then processed by sLORETA in a statistical non-parametric mapping analysis. RESULTS: The current density distribution of δ and α oscillations differed significantly during the four tasks, while θ, β and γ oscillations did not. Changes in δ oscillations of the brain during mental fatigue were detected mainly in the postcentral gyrus (BA2 and BA3), precentral gyrus (BA4 and BA6), inferior temporal gyrus (BA20), and superior temporal gyrus (BA38). The α oscillations were found mainly decreased in the postcentral gyrus (BA2) and inferior parietal lobule (BA40) when the task was in progress compared with the end of the task. CONCLUSION: The superior temporal gyrus and somatosensory cortex were the main activated cortical regions during the simulated ATC task. The α and δ oscillations showed contrasting activity during simulated ATC task, which might reflect the release of task-relevant brain's areas from inhibition and enhance the neural activity.