Flight fatigue is a combined result of both physical and mental fatigue. Fatigue assessment methods primarily include subjective scales, and objective methods that analyze various physiological signals related to flight fatigue. These involve collecting and analyzing key physiological parameters, such as electrocardiogram (ECG), electromyogram (EMG), and comparing them with subjective evaluations to determine whether a pilot is experiencing fatigue. However, most studies on long-duration fatigue have focused on automotive driving, typically over periods of about 4 h. Given the significant differences between fighter jet operations, which involve extreme combat conditions and extended flight durations, it is necessary to conduct long-duration flight experiments lasting around 8 h. There is currently a lack of a comprehensive and effective system for evaluating pilot fatigue during long-duration flights in fighter jets. Using a single physiological signal to evaluate and predict pilot fatigue carries inherent errors and uncertainties. Research has increasingly focused on fusing multiple physiological signals to improve fatigue detection accuracy. This study, based on the ejection seats of China’s 4th-generation fighter jets, aims to assess both mental and physical fatigue in pilots after prolonged simulated flights, identify effective fatigue evaluation indicators, and develop a robust evaluation model.