Air operators may find the information here of use in developing fatigue risk management system (FRMS) processes for risk control.
Kathryn Jones of the Civil Aviation Authority of the United Kingdom (UK) created this content, and we are using it with permission.
| Fatigue Hazard Description | Possible Crew Performance Implications | Possible Mitigation Measures |
|---|---|---|
| Long duty periods | Reduced alertness, impaired attention, degraded reaction time | Maximum FDP limit, maximum duty period, extra rest requirements, rolling duty limits |
| Company extended duty periods | Transient fatigue, reduced alertness, impaired attention, degraded reaction time | Maximum limit on extension, restriction on the number of times a week/month that extensions are allowed, extra rest requirements both surrounding the extended duty and monthly for cumulative fatigue prevention. |
| Sleep deprivation / deficit due to waking / finishing duty in the WOCL | Degraded alertness, extended period of wakefulness, increase in transient fatigue, errors / slips / lapses in performance. | Reduce the allowable maximum FDP for duties where the crew member reports after wakes in / actually reports in / finishes in or FDP encompasses the WOCL, maximum number of these duties in a work block or number of days, planning of these duties to enable flow of work and optimum sleep opportunity. |
| Night Duties | Transient fatigue, sleep deprivation, impaired / reduced sleep due to daytime rest, degraded alertness, errors / slips / lapses in performance | Reduce allowable FDP, maximum numbers of such duties allowed in a work block or number of days, sole night freight operation with set rest requirements and pattern construction. |
| Sector Workload | Fatigue risk increases with each sector due to task / workload fatigue, reduced alertness, degraded performance, transient fatigue | Allowable FDP decreased by the number of sectors worked |
| High Cumulative workload | Cumulative fatigue, increased automation dependence, reduced communication, mood, impaired decision-making, degraded performance, errors and lapses, communication issues. | Limit on of successive long duty periods together, rolling limits on weekly, bi-weekly, monthly, annual duty hours, rolling limits on monthly, quarterly, annual flying hours. Cumulative fatigue management through a required minimum number of days off, including weekly break, long breaks (2 + days off), monthly requirements, days off to include local nights of sleep. |
| Circadian Disruption - mixing duty transitions (early/late/night/long duties/crossing time zones) | Transient and cumulative fatigue issues, shortened sleep opportunity, reduced alertness, slow reaction time, task fixation, decreased vigilance | Regulations around duty construction, restrictions on number of early/late/night transitions in a work block, reduced max FDP for duties following a rest period of 18 - 30 hours due to reduction of optimum sleep opportunity and risk of extended periods of wakefulness. Minimum rest / days off requirements following time zone crossing duties / blocks of working containing time zone multiple time zones. |
| Time zone de-synchronization | Transient and cumulative fatigue issues, degraded alertness, reduced communication, degraded performance | Duty restrictions for a set period of time or based on rest period achieve (full sleep opportunities) where the crew member moves more than 2 time zones from the one they reported in. Minimum time set before a crew could be considered time zone adjusted or acclimatized. Minimum rest / days off requirements following time zone crossing duties / blocks of working containing time zone multiple time zones. |
| Rest opportunity - minimums and sub-optimal periods | Cumulative fatigue, increased automation dependence, reduced communication, mood, impaired decision-making, degraded performance, errors and lapses, communication issues. | Set a minimum rest period (12 hours) between duties to allow for a sleep opportunity, physiological needs, travelling to duty (dependent on home or away from base place of rest) and recovery from long/extended duty periods. Reduced max FDP for duties following a rest period of 18 - 30 hours due to reduction of optimum sleep opportunity and risk of extended periods of wakefulness. |
| In-flight relief and extending the FDP - facilities and time | Degraded alertness, extended period of wakefulness, increase in transient fatigue, errors / slips / lapses in performance. | Minimum rest period onboard requirement, extension of FDP dependent on type of onboard rest facilities and number of additional crew carried, use of depart window to optimize crew alertness during critical phases of flight, requirement of prior notification of crew position for optimal rest planning (operating or relief crew) |
| Standby - Airport | Reduced alertness, impaired attention, degraded reaction time, decreased vigilance. | Duty and FDP starts at report and standby plus any FDP is calculated to the maximum of FDP allowance for time of report. Maximum duty period. Full rest period required following airport standby. Counts in full for duty hours. |
| Standby - elsewhere | Extended period of wakefulness, increase in transient fatigue, errors / slips / lapses in performance. | Relationship of the length of time on standby and the allowable FDP at callout factored to mitigated extended periods of wakefulness. Maximum duty period on standby and maximum duty period plus FDP / allowable FDP factored by time spent on standby. Standby callout requirements (immediate readiness / long call / contactable / available) used to develop different levels of requirement based on worst-case fatigue level. Calculations of cumulative duty hours dependent on type of standby and whether crew are called out or not. Full rest period prior to next duty. |
| Split Duty | Reduced alertness, impaired attention, degraded reaction time, decreased vigilance, impaired attention. | Minimum consecutive number of hours for the rest period of split (time to allow crew to unwind and achieve meaningful rest, 3 hours). Method of calculating the percentage of the rest period that can be used to increase the FDP. Maximum time before the rest period must take place in suitable accommodation to allow for a split duty to be taken. FDP plus increase from split to run continuously from initial report to final on chocks. Subsequent rest period the same as the total duty. |
| Disruption - on the day | Extended wakefulness, transient fatigue issues, long duty day, stress and hassle leading to extended FDP and / or shortened sleep opportunity, reduced alertness, slow reaction time, task fixation, decreased vigilance errors / slips / lapses in performance. | Process for PIC to extend an FDP or reduce a rest period based on the circumstances on the day and of the crew. Realistic scheduling of flights to allow for completion of FDP with the limits. Requirement for operator to demonstrate compliance and change schedules where planning regularly requires PIC’s discretion (15%). PIC to also be allowed to reduce FDP / extend rest where circumstances of his crew require it. |
| Disruption - before the day | Transient and cumulative fatigue issues, shortened / sub-optimal sleep opportunity, reduced alertness, slow reaction time, task fixation, decreased vigilance. | Graded penalty for changes to rostered duty based on the time movement of the duty from the original duty and the period of notification of the change. Restriction on the number of transitions of duty that can be achieved within a duty block. |
| Positioning duties - before an FDP, immediately after an FDP. | Extended period of wakefulness, increase in transient fatigue, errors / slips / lapses in performance. | Position duties to count as FDP when immediately prior to an FDP. Immediately post an FDP, positioning is duty and the cumulative duty total required for rest period calculation, counts as full duty hours, impact of method of positioning transport factored into the FDP (taxi, self drive, airline) |
| Travelling time | Transient and cumulative fatigue, extended periods of wakefulness, reduced / shortened sleep opportunity leading to reduced alertness, slow reaction times, errors in performance. | Require a set home base airport with a maximum travelling time beyond which crew are recommended to have alternative accommodation closer to base. Minimum rest periods at home base to make allowance for travelling time. Minimum rest periods away from base can be slightly reduced where travelling time is minimal but must still take account of a full sleep opportunity and physiological requirements and be increased where travelling time to place of rest exceeds minimal time (15 minutes). |
| Cumulative fatigue | Cumulative fatigue, increased automation dependence, reduced communication, mood, impaired decision-making, degraded performance, errors and lapses, communication issues, general overall degradation of performance |
Operator demonstration of management of fatigue both short and long term, work plan, fatigue reports, by implementation of an FRMS within their SMS. Crew have clear guidance and requirements to make good use of rest periods and report fit for duty. |