Background Long-duration flight missions can lead to physical and mental fatigue in pilots, which may affect their attention and cognitive abilities, thereby affecting their operational abilities.

Objective To evaluate the influence of different duration of flight missions on the cognitive ability of helicopter pilots by comparing the cognitive changes of pilots before and after flight.

Methods The age, quality of sleep in the last month and self-assessment fatigue severity of 95 male helicopter pilots of four helicopter types in army aviation (type-1, type-2, type-3 and type-4) were investigated after different flight durations (3 h and 6 h), and cognitive ability tests (including visual alertness, digital decoding, target tracking and spatial attention span test) were performed before and after the flight.

Results The results showed that most pilots slept well (“very good” accounting for 41.05%; “good” for 56.84%; “fair” for 2.11%). The age of the type-1 and type-4 pilots in the 6 h group was significantly higher than that of the 3 h group, but there was no significant difference in the self-assessment fatigue severity of the four types of helicopter pilots. The cognitive ability test results showed that there were no significant differences in the psychomotor vigilance tests accuracy, the accuracy rate of digital decoding and spatial attention span tests, and the average distance of target tracking of the helicopter pilots before and after the 3 h or 6 h flight.

Conclusion There is no significant difference in the fatigue severity of the four types of helicopter pilots after completing different duration of flight missions, and the 3 h or 6 h flight has no significant adverse effects on the pilot's cognitive ability.