Fatigue is an expected part of life for most adults. For the average person, fatigue presents a minor inconvenience, usually resolved with a nap or by stopping the activity that brought it on. For a pilot, fatigue is an occupational hazard.

Accident statistics, reports from pilots themselves, and operational flight studies all show that fatigue is a clear concern within aviation operations. In addition to its effect on safety, fatigue can also have other long-term consequences. Understanding the physiological factors that contribute to fatigue is essential to improving safety, performance, and productivity; and developing effective fatigue management strategies to counter it.

Different Types of Fatigue

Fatigue is defined as a physiological state in which there is decreased capacity to perform cognitive tasks and an increased variability in performance. There are several types of fatigue as defined by the FAA, and all can be experienced by pilots during the course of their normal duties.

• ACUTE FATIGUE is caused by a recent loss of sleep (within the past 24 hours). Humans are detrimentally affected by having less than 8 hours of sleep in the past 24 hours, by being awake more than 17 hours, or by working between the hours of midnight and 6:00 am.
• CHRONIC FATIGUE is caused by not having enough sleep (8 hours in a 24-hour period) for multiple days in a row. This type of fatigue causes performance degradation and has a slow recovery period.
• CIRCADIAN FATIGUE is caused by reduced human performance during a person’s circadian low (typically between 2:00am and 6:00am).
• CUMULATIVE FATIGUE is brought on by repeated mild sleep restrictions or extended hours awake over a series of days.
• TRANSIENT FATIGUE is acute fatigue brought on by extreme sleep deprivation or extended hours awake within a couple of days.

Fatigue Awareness

Fatigue can manifest itself in a variety of ways. Signs of fatigue include:

• Degraded performance; such as making multiple mistakes or taking an unusually long time to perform a normal task.
• Reduced attention time or memory loss; such as not remembering if a flight received clearance to land.
• Loss of situational awareness. This will often lead to errors in judgment and increased reaction time. This situation may be recognized by another crewmember before it is noticed by the affected pilot.

FAA Regulations for Fatigue Management

The FAA regulates crew rest for commercial operations through its FAR 135 and 121 regulations (and here are the FAA FAR Part 135 crew duty rest times regulations). Crew rest, as defined by the FARs, is any time that a crewmember is free from all duties and responsibilities, including flying and administrative work. The FAA places strict limitations on minimum crew rest periods. In spite of mandatory rest periods, pilots still find it difficult to acquire 8 hours of uninterrupted sleep during the 24/7 schedules that often define today’s flight operations.

Because of this, well-planned, science-based fatigue management strategies are crucial for managing sleep loss, sustained periods of wakefulness, and circadian factors that are primary contributors to fatigue-related errors committed during flight operations.

To operate effectively and safely, it is vital for pilots to not only understand the physiological processes of sleep and fatigue but also to employ effective coping strategies.

TrainingBoom’s CRM – Fatigue and Rest online training module can enable your team to protect themselves against the dangers of fatigue.

To learn more, contact us for a demo or hear what our customers have to say.