Taking Controlled Rest in Aviation: How Pilot Fatigue Management Enhances Flight Safety

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Pilots are known for their resilience in the face of fatigue during long-haul flights. With long and unpredictable working hours, the aviation industry has seen significant efforts to address sleepiness. Controlled rest on the flight deck is one such measure aimed at combating unexpected sleepiness. However, a recent study by Cassie J. Hilditch and colleagues aimed to identify why pilots opt for this practice and its impact on their attention levels at critical stages like top-of-descent.

Understanding the Importance of Controlled Rest

Controlled rest allows pilots to take a brief nap in the cockpit during long flights under specific guidelines to alleviate unplanned sleepiness. This helps pilots rest while staying within safety protocols and reduces the chances of uncontrolled, unexpected napping, which could jeopardize flight safety.

Despite the benefits, the concept remains controversial due to varying global regulations and concerns about potential risks. The authors aimed to explore the factors influencing a pilot’s decision to take controlled rest and its effects on alertness and cognitive function.

Research Objectives and Approach

This study had three main goals:

  1. Pre-flight Factors and Timing: Understanding how factors like pre-flight sleep history and the flight’s time of day influence a pilot’s likelihood of opting for controlled rest.
  2. Predictive Measures: Evaluating if neurobehavioral tests conducted pre-flight can predict the likelihood of in-flight controlled rest.
  3. Rest Outcomes: Measuring the impact of controlled rest on attention and sleepiness at top-of-descent.

Researchers collected data from 31 pilots across 120 flights lasting longer than six hours. Pilots wore actiwatches to monitor sleep before and during trips and completed psychomotor vigilance tests (PVT) and Karolinska Sleepiness Scale (KSS) surveys pre-flight and at top-of-descent.

Key Findings

  1. Increased Rest on Night Flights: Pilots were 14 times more likely to take controlled rest during night flights compared to day flights. This is probably due to the circadian low at night when maintaining alertness is challenging.
  2. Predicting Rest Use: Pilots with higher pre-flight KSS sleepiness scores were about four times more likely to take controlled rest, suggesting pilots self-assess their need for this measure.
  3. Improved Response Speeds: Pilots who took controlled rest had faster response speeds at the top of the descent, even after considering pre-flight scores, suggesting enhanced vigilant attention.
  4. No Significant Impact on Sleepiness Scores: Despite improved response speeds, pilots’ KSS sleepiness ratings remained unchanged after controlled rest.

Implications for Aviation

The results highlight that controlled rest is particularly valuable during unaugmented night flights when pilots are most susceptible to fatigue. The modest improvement in response speeds at top-of-descent could mean better decision-making and reaction times during critical flight phases. However, these results also emphasize that controlled rest alone isn’t enough to address chronic fatigue, and it’s crucial to supplement this with other fatigue management strategies.

Future Directions

Further research is needed to understand the qualitative aspects influencing controlled rest, such as cultural attitudes and individual preferences. Studying pre- and post-controlled rest sleepiness and performance more frequently could help optimize this fatigue management tool. Additionally, evaluating sleep patterns with more precision through electroencephalography might offer deeper insights into sleep quality.


Controlled rest on the flight deck can be a valuable tool for managing fatigue, especially on long night flights. This practice might also improve vigilance at critical flight stages, ultimately contributing to safer skies.

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About the Author

Jon Scaccia, with a Ph.D. in clinical-community psychology and a research fellowship at the US Department of Health and Human Services with expertise in public health systems and quality programs. He specializes in implementing innovative, data-informed strategies to enhance community health and development. Jon helped develop the R=MC² readiness model, which aids organizations in effectively navigating change.

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