Modeling Fatigue Associated with Workload in Commercial Aviation Operations

Introduction: Biomathematical models are widely used in commercial aviation to assess fatigue risk during operations. Most models are fundamentally influenced by the two-process model of sleep regulation, which estimates fatigue in relation to prior sleep duration and circadian rhythm/time of day. However, fatigue can also be due to workload. Many factors that contribute to workload are predictably related to scheduling and can be incorporated into a prospective model of fatigue. The biomathematical modeling software SAFTE-FAST recently introduced a Workload Calculator to allow users to estimate job demands during operations. Workload in SAFTE-FAST is modeled as a separate, but intervening, process from cognitive alertness related to time of day or sleep history. An important step toward accurate modeling of workload is to test the accuracy of the Workload Calculator against a real-world measure, like the NASA Task Load Index (TLX) scale. This study compared the accuracy of SAFTE-FAST Workload predictions against TLX scores taken by pilots during normal flight operations using equivalence testing.