Workload predictions from a biomathematical model compared to top-of-descent NASA Task Load Index scores in commercial pilots

Abstract

Biomathematical models of fatigue (BMMFs) are commonly used to predict cognitive alertness in commercial aviation. Accounting for workload in association with routine job tasks may help BMMFs to more accurately predict fatigue in real world operations. This study compared the accuracy of BMMF workload predictions (SF Workload) against pilot self-report of workload during normal flight operations. N=99 pilots from a major Asia-based airline completed the NASA Task Load Index (TLX) at top of descent (TOD) during a multiple-flight three-day roster that consisted of daytime flying. SF Workload predictions and TLX scores were normalized to a 100-point scale and compared using equivalence testing. SF Workload predictions were statistically non-different from pilot TLX scores at the same TOD (64 ± 7 vs. 65 ± 15; both t=1.56, p=0.06) using the two one-sided t-test (TOST) approach, indicating high workload and that BMMF predictions are non-inferior to pilot self-report as a means of estimating workload. Establishing the accuracy of workload predictions against real-world reports in a commercial pilot population is an important step towards risk management in situations where high workload may create a safety risk.