The association between fatigue, sleep loss and simulated flight data measures in regional airline pilots : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University, Sleep/Wake Research Centre, School of Health Sciences, Wellington, New Zealand

Abstract

The impact of fatigue on flight crew performance can be investigated by identifying causal links between fatigue related impairment and embedded performance measures. To investigate the feasibility of recording simulated flight data measures in operational settings, this study sought to identify what key processes need to be in place. In addition, by investigating the association between measures of fatigue and simulated flight data measures, the study also sought to identify if fatigue related changes in flight crew performance are detectable.

Sixteen regional airline pilots, working as eight flight crew, were monitored during a 12 day flight duty period protocol. The protocol consisted of two simulated flights, one which followed four consecutive days where flight duty periods were scheduled (the non-rested condition) and one which followed two consecutive days free from duty (the rested condition). The simulated flights, conducted in a full flight simulator, were representative of normal flights.

Although logistically challenging, the study demonstrated the feasibility of conducting a simulator study in operational settings and that it is possible to record simulated flight data measures from a Simulator Operations Quality Assurance programme. The flight duty period protocol was partially successful. In the non-rested condition, participants initially experienced cumulative sleep debt and ratings of fatigue and sleepiness were significantly higher both before and following each simulated flight. However, following the last sleep opportunity before each simulated flight, there were no flight duty period protocol differences in any sleep related variables aside from cumulative sleep debt and time since sleep. Changes in flight crew performance were identified, with greater variability observed in some initial climb measures during the non-rested condition. Findings were mixed, an increase in time since sleep was associated with reduced variability in some initial climb measures and time taken to complete the go around/missed approach procedure checklist increased with greater time since sleep and with a greater amount of sleep in the previous 48 hour period. Increases in ratings of fatigue and sleepiness were associated with increased variation in some initial climb measures.

Results from this study illustrate that the methodology and the accuracy of simulated flight data measures is sufficient to warrant further investigation into the influence of fatigue on flight crew performance.