The present study delves into the examination of mental workload experienced by pilots operating within the context of airfield traffic patterns. Within this framework, electrocardiographic (ECG) indicators indicative of mental workload were identified. A comprehensive investigation was conducted, involving a six-degree-of-freedom simulation flight experiment encompassing airfield traffic pattern missions undertaken by pilot students, with the aim of quantifying mental workload levels throughout various phases of flight. Data were systematically gathered across distinct flight stages. Employing factor analysis, the ECG indicators of pilots were utilized to construct a robust model characterizing pilot mental workload. Subsequently, an in-depth analysis and validation of the dynamics of mental workload levels among pilots across diverse flight phases were performed. The findings underscore the enhanced reliability and validity of the heart rate variability index as opposed to the heart rate index in gauging pilot mental workload. Furthermore, the results reveal that during takeoff and ascent stages, mental workload tends to be relatively lower and exhibits a declining trajectory, whereas during the cruise phase, mental workload remains at a diminished level with a smooth, gradual progression. And the approach and landing phase registers the highest levels of mental workload. In addition, unanticipated events exert a discernible impact on mental workload, eliciting a substantial upsurge therein.