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UK Civil Aviation Regulations

These are published by the CAA on our UK Regulations pages. EU Regulations and EASA Access Guides published by EASA no longer apply in the UK. Our website and publications are being reviewed to update all references. Any references to EU law and EASA Access guides should be disregarded and where applicable the equivalent UK versions referred to instead.

What is fatigue?

A physiological state of reduced mental or physical performance capability resulting from sleep loss, extended wakefulness, circadian phase, and/or workload (mental and/or physical activity) that can impair a person’s alertness and ability to perform safety-related operational duties (ICAO).

Fatigue can also be mental or emotional in cases where there is significant emotional or mental strain on an individual.

Fatigue can affect anyone; aviation/aerospace maintenance personnel, pilots, cabin crew, supervisors, operations personnel, air traffic controllers and management.

Therefore, it is important to consider the risks of fatigue and how these can be mitigated, for optimal human performance.

Fatigue is a hazard and the risks should be managed within management systems and there are also individual responsibilities.


Risk factors leading to fatigue (not exhaustive):

• Changing work hours/roster patterns

• Changing time zones

• Periods of extended wakefulness

• Excessive workload – physical and cognitive

• Long duty periods

• Loss of sleep

• Emotional stress – from home life or the workplace

• Nutrition

• Illness

• Medication

• Stress as a result of a critical incidents an individual may have experienced or previous operational disruption


Risks associated to operations and the individual arising from fatigue (not exhaustive):

• Impaired judgement and decision making

• Slower reaction time

• Reduced alertness and awareness

• Memory lapses

• Degraded Human Performance

• Reduced ability to process information

• Poor coordination

• Errors

• Less communicative or attentive

• Underestimation of risk

• Physiological issues and general ill health, such as cardiovascular and digestive problems


Mitigating factors:

• Fatigue risks should be managed within the Safety Management System

• Just culture

• Know and look for signs of fatigue in yourself and others

• Flight time limitations, and regulation of air traffic controller hours, and operational staff rostering

• Manage sleep routines for the upcoming rostered duties

• Good diet/nutrition

• Exercise to improve mental and physical health

• Manage workload – delegation, workload assessments

• Optimise schedule for safety critical tasks where possible to set shifts/ times (e.g. day shift)

• Support in the workplace