Data from two simulator experiments were examined to investigate whether performing an auditory task influences pilots' gaze behaviour. Gaze behaviour was measured while participants performed a manual flying task with an auditory task (dual-task condition) or without (single-task condition). Experiment 1 took place in a fixed-base, fixed-wing simulator with 15 novice military pilots. Experiment 2 took place in a moving-base, rotary-wing simulator with 13 experienced military helicopter pilots. Percentage dwell time outside significantly increased in the dual-task condition compared to the single-task condition in both experiments, by a factor of 1.2 and 1.5 respectively. Mean duration of fixations outside significantly increased for pilots, while it decreased for novices. In novices, altitude control performance was also significantly reduced when performing the auditory task, whereas bank angle control performance significantly increased in experienced pilots. The impact on gaze behaviour may potentially serve as a behavioural indicator of pilot auditory workload.