Validating and extending the three process model of alertness in airline operations

Area of Science:

• Occupational Health
• Transportation Safety
• Biomathematics

Background:

• Sleepiness and fatigue are critical risk factors in the transportation industry.
• Bio-mathematical modeling aids in assessing work schedule safety within Fatigue Risk Management Systems (FRMS).
• The Three Process Model (TPM) is a key tool for predicting sleepiness.

Purpose of the Study:

• To validate the Three Process Model (TPM) for aircrew sleepiness prediction.
• To extend the TPM with functions for modeling jetlag and assessing sleepiness risk in various shift schedules.
• To evaluate the model's accuracy using real-world aircrew data.

Main Methods:

• Collected sleep and sleepiness data from 136 aircrews using a handheld device application.
• Employed multilevel linear and non-linear mixed-effects models to analyze data and validate the TPM.
• Exploratively analyzed model complexity, including a two-process (S+C) model with adjusted circadian phases.

Main Results:

• TPM predictions showed a correlation with observed sleepiness ratings in aircrews.
• The default TPM model can be simplified to a two-process model (S+C) with adjusted circadian phases.
• Extended model includes jetlag acclimatization, individual differences, and probability of sleepiness for risk assessment.

Conclusions:

• The validated and enhanced TPM provides a robust tool for assessing sleepiness and fatigue risks in aviation.
• Model simplification and extensions improve its applicability for diverse shift schedules and jetlag scenarios.
• The findings support the use of advanced sleepiness modeling for improving safety in the transport sector.