0184 Can Subjective Sleepiness Pre-flight Predict the Use of Controlled Rest on the Flight Deck?

Abstract

Abstract Introduction Pilot sleepiness in flight continues to be an issue in aviation due to irregular and extended working hours. In some regions of the world, pilots are allowed to use an in-flight countermeasure called controlled rest, which involves taking a short nap on the flight deck. The use of this countermeasure in practice is understudied. We aimed to investigate whether subjective sleepiness ratings taken pre-flight are predictive of controlled rest use. Methods Data from 94 long (> 6 hours flight duration), non-augmented (two flight crewmembers) flights were analyzed (n = 30 pilots). Mixed-effects logistic regression was used to assess the likelihood of controlled rest based on a Karolinska Sleepiness Scale rating (KSS) taken at pre-flight. Results Controlled rest was taken on 62.77% (n = 59) of the analyzed flights. Pilots with higher KSS ratings (i.e., subjectively sleepier) pre-flight were more likely to take controlled rest during the subsequent flight (b ± SE: 1.03 ± 0.33; OR = 2.81, 95% CI [1.47, 5.37]; p = .002; R2 (Marginal): .28, R2 (Conditional): .51). That is, for every one-unit increase in KSS ratings, there was a near three-fold increase in the odds of taking controlled rest in flight. Conclusion Our results suggest that subjective sleepiness prior to a flight may be predictive of the decision to take controlled rest later in the flight. Further research is needed to understand the influence of other scheduling factors and individual differences. Support (if any) NASA Airspace Operations and Safety Program, System-Wide Safety Project.