Technical Papers

Fatigue Risk Assessment Methodologies

EASA 2nd FRM Workshop Cologne November 2015
Author: Kristjof Tritschler

At the 2nd EASA FRMS Workshop 2015 different methodologies were presented to provide an overview of how these may be applied to assess fatigue risk. Different risk assessment approaches were explained with their advantages and shortcomings. The Fatigue Factor Assessment and Mitigation Table was proposed as one fatigue-specific risk assessment methodology for a particular duty or work pattern. This paper contains several amendments to the Luxemburg version:

  • The different methodologies are discussed more in depth;
  • The fatigue factor assessment table is here used with numbers instead of marks;
  • The severity classification is outlined in one version for the worst case, indicating the need for mitigation and the other version to assess the acceptability and expected fatigue impairment after the mitigations;
  • A new type of risk matrix is added to assess fatigue risk as a function of exposure to fatigue factors in the severity dimension and the number of flights per crew member per working week in the likelihood dimension.

Download: Tritschler 2015, Fatigue Risk Assessment Methodologies. Paper presented at EASA FRM Workshop Cologne

In order to download Tritschler 2015, Fatigue Risk Assessment Methodologies please fill out the following fields.



    Fatigue Assessment and Mitigation Methodology

    FRMS Forum Luxembourg 2015
    Author: Kristjof Tritschler, Manager FRMS Germanwings
    At the FRMS Forum 2015 a practicable methodology has been presented for fatigue assessment and mitigation. The proposed “Fatigue Assessment and Mitigation Table” is a simple and profound approach to assess fatigue of a single duty or type of shift, based on numerous scientific studies. This methodology starts by the identification of the root causes of fatigue and provides effective mitigation measures in very short time. Mitigations include the previous nights, shift-changes and workload factors.



    The Influence of Workload Factors on Flight Crew Fatigue

    International Aviation Safety Seminar (IASS) 2010, Milano, Italia
    Authors: Kristjof Tritschler and Steve Bond (Tutor City University London)
    Background: Fatigue is a recognised safety issue in aviation. Comprehensive scientific research has identified time since awake, sleep loss, time on task and circadian disruption as the main causes of fatigue. Today’s requirement for high crew and aircraft utilisation, with tight schedules and short turn-around times between flights, contribute to increased perception of high workload, especially on short-haul. This paper provides guidance how to integrate workload into an operator’s Fatigue Risk Management System (FRMS) and focuses on the influence of workload on flight crew fatigue.
    Methods: Scientific literature has been specifically reviewed to link workload with fatigue. To complement previous research, a field study with 40 pilots of a German Low Cost Carrier was performed. A workload questionnaire included a comparison of the flight- and ground-phase in 6 dimensions of workload. 21 workaday factors had to be assessed, measuring activation, success and fatigue. Importance of team cooperation to manage the workload and the frequency of applied workload management strategies closed the questionnaire.
    Results: 82% of the subjects rated the work on ground to be equally or more exhaustive than the flight phase. “Effort”, “mental demand”, “temporal demands” and “frustration” were higher “on ground” compared to “in flight”. The most significant workaday factors in this study were “critical fuel status”, “aircraft change”, “no ramp agent”, “deficient documentation” and “tight schedule”. To cope with high workload, team work is considered very important for pilots, important for cabin crew, less important for others outside the aircraft. “Plan ahead” is the most frequently applied workload management strategy, followed by “prioritise work” and “take time”. Allocated tasks are less frequently delegated or deferred.
    Conclusion: Workload is one cause of fatigue. But workload is less relevant than expected, however workload management is considered a much more efficient strategy to control fatigue than anticipated. The ground phase is considered a fatigue-relevant phase of “flight” with high temporal pressures and many variables outside the control of the crew like sluggish ground handling or delay. One reason of perceived high workload and fatigue on ground is high activation, sometimes resulting in limited success, rather than task demands. This survey confirms previous scientific studies that time pressure is the most important factor on workload. Workload is seen as the third dimension contained in an effective FRMS, after roster and lifestyle issues.
    Recommendations: Operators should include workload management into their FRMS. Workload on ground may be reduced by robust processes, reliable ground service providers and competent ramp agents. Number of flights, including turn-around times in between, should be limited depending on the complexity of operation and support provided. Operators should review allocated tasks of their crewmembers for equal workload distribution and provide some flexibility to avoid overload of one crewmember. Operators should provide training on fatigue and workload management strategies. Individuals should know and apply effective workload management strategies to prevent and recover from mental fatigue on duty in order to control the risk of fatigue.

    Kristjof Tritschler
    MSc Air Safety Management
    Spitzäckerweg 13
    DE 72766 Reutlingen

    T: +49 7121 4348253


    VAT / Ust-IDNr:
    DE 303 949 186
    FA: Stuttgart, Germany

    Pictures: own (Cockpit)
    NASA Image Galleries