Fatigue Management Approaches


In general, ICAO Standards and Recommended Practices (SARPs) in various Annexes support two distinct methods for managing fatigue:

  1. a prescriptive approach that requires the Service Provider to comply with duty time limits defined by the State, while managing fatigue hazards using the SMS processes that are in place for managing safety hazards in general ; and

  2. a performance-based​ approach that requires the Service Provider to implement a Fatigue Risk Management System (FRMS) that is approved by the State.


​These approaches share two important features

1. They must be based on scientific principles, knowledge and operational experience:


  • Getting enough sleep (both quantity and quality) on a regular basis is essential for restoring the brain and body. The drive for sleep increases with time awake.

  • Reducing the amount or the quality of sleep, even for a single night, decreases the ability to function and increases sleepiness the next day.

  • The circadian body clock affects the timing and quality of sleep and produces daily highs and lows in performance on various tasks.

  • Workload can contribute to an individual’s level of fatigue. Low workload may unmask physiological sleepiness while high workload may exceed the capacity of a fatigued individual.

  • Knowledge of the operational and organizational context, as well as understanding of the constraints and motivations of the workforce must be considered alongside the science when determining the safety risk that a fatigue-impaired individual represents in that context.   

2. Fatigue management has to be a shared responsibility between the State, Service Providers and individuals:
  • The State is responsible for providing a regulatory framework that enables fatigue management and ensuring that the Service Provider is managing fatigue-related risks to achieve an acceptable level of safety performance.

  • Service Providers are responsible for providing fatigue management education, implementing work schedules that enable individuals to perform their duties safely, and having processes for monitoring and managing fatigue hazards.

  • Individuals are responsible for arriving fit for duty, including making appropriate use of non-work periods to obtain sleep, and for reporting fatigue hazards.

Prescriptive Approach

No "correct" limits, just informed boundaries
- ICAO Standards do not identify the actual limits
- Nor does science!
- Identifying prescribed duty limits requires a risk assessment
Prescriptive limitation regulations identify maximum work periods and minimum non-work periods for specific groups of aviation professionals.  The prescribed limits are essentially informed boundaries identified by the State, inside which the Service Provider must manage their fatigue-related risks as part of their existing safety management processes.  With a prescriptive approach, fatigue is one of the possible hazards that the SMS should consider, but data-driven evidence related to fatigue is not specifically and actively collected unless a fatigue issue has been identified by the SMS.  ​
More information can be found in the Guidance Material on the Resources page.

Performance-based Approach (FRMS)

FRMS is an opportunity for Service Providers to use advances in scientific knowledge to improve safety and gain operational flexibility at the same time​.
The performance-based Fatigue Risk Management System (FRMS) approach represents an opportunity for Service Providers to use advances in scientific knowledge to improve safety, use resources more efficiently and increase operational flexibility. FRMS allows the Service Provider to move outside of the prescribed limits and is focused on managing the actual fatigue risk in the operations to which it applies (rather than addressing the predicted fatigue risk in general, which is the basis of prescriptive limits). FRMS has additional requirements to ensure a level of safety that is at least equivalent to that achieved by operating within the prescriptive limitations and considering fatigue as one of the risks to be managed using generic SMS processes. Where a service provider already has sufficiently mature SMS processes in place, it should not be necessary for them to develop entirely new processes to implement FRMS. Rather, the service provider can build upon the organization’s existing SMS processes to address the added requirements of an FRMS.
Having an FRMS still requires having maximum duty times and minimum rest (or non-work periods), but these are proposed by the Service Provider, may differ from the prescribed limits and must be approved by the State. To get approval, the Service Provider must demonstrate to the regulator that it has appropriate processes and mitigations to achieve an acceptable level of risk.

Not every State should offer FRMS regulations​

The oversight of FRMS, as a performance-based approach, requires extra resources, and a well-trained State inspectorate.  Prescriptive Fatigue Management regulations provide the baseline, in terms of safety equivalence, from which an FRMS is assessed.  Therefore, before providing FRMS regulations, the State needs to be confident that it has robust, scientifically-based prescriptive limitation regulations appropriate to the context in which they are to be used and that their inspectors can adequately oversee the prescriptive limitation regulations, including the use of SMS processes to manage any identified fatigue risks.
While FRMS can offer considerable safety and efficiency benefits, potential safety benefits may be reversed if the State does not have the resources to develop the supporting regulatory processes and provide the necessary oversight.

Not every service provider should implement an FRMS

Where their State has FRMS regulations, Service Providers can decide to manage none, some, or all of their operations under an FRMS.  While FRMS offers the potential for considerable operational flexibility benefits, FRMS shouldn’t be considered a “right”; it’s more a “privilege” for those who have demonstrated that they can use mature SMS processes to manage fatigue and who are prepared to go even further to develop an approved FRMS.
The cost and complexity of implementing an approved FRMS may not be justified for operations that remain inside prescribed limits and where fatigue-related risk is low.  However, this does not preclude a Service Provider from using FRMS processes to manage their fatigue risks within the prescribed limits.
More information can be found in the Guidance Material​ on the Resources page.​
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