Flight Crew Alertness and Sleep Relative to Timing of In-Flight Rest Periods in Long-Haul Flights

Area of Science:

• Aviation Physiology
• Sleep Science
• Human Factors in Flight Operations

Background:

• Augmented long-haul flights utilize in-flight breaks for pilot rest.
• Current U.S. Federal Aviation Administration regulations restrict the landing pilot to the third rest break.
• The efficacy of this restriction on pilot sleep and performance is not well understood.

Purpose of the Study:

• To investigate the impact of rest break timing on pilot sleep, alertness, and fatigue.
• To compare self-reported sleep duration and psychometric ratings between pilots using the second versus third in-flight rest break.
• To determine if the second rest break is noninferior to the third rest break for landing pilot readiness.

Main Methods:

• A survey was administered to pilots on augmented operations in two U.S. commercial airlines.
• Participants reported in-flight sleep duration and completed the Samn-Perelli fatigue and Karolinska Sleepiness scales at top-of-descent.
• Noninferiority analysis compared the second and third rest breaks, with repeated measures ANOVA assessing the influence of home-base time (HBT).

Main Results:

• Data from 500 pilots across 787 flights indicated the second rest break was noninferior to the third for sleep duration (1.5 vs. 1.4 hours), fatigue (2.0 vs. 2.9), and sleepiness (2.6 vs. 3.8).
• Pilot sleep, fatigue, and sleepiness measures were significantly influenced by the circadian time of day (HBT).
• No significant difference was found in key performance indicators between pilots using the second versus third rest break.

Conclusions:

• Self-reported sleep, fatigue, and sleepiness for pilots using the second rest break were equivalent or superior to those using the third break.
• Findings support offering pilots flexibility in choosing between the second or third in-flight rest break.
• This flexibility may enhance pilot readiness for landing during augmented flight operations.