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FATIGUE and FATIGUE MANAGEMENT SYSTEMS
TOPICS - The Nature of fatigue in flight operations Traditional Fatigue Management Systems The Fatigue Risk Management System Fatigue in Human Factors Training
FATIGUE The average population is awake for 16 hours a day and sleeps for 8 hours Where less than 8 hours is obtained, or sleep is disrupted, the body starts to enter a state of fatigue
FATIGUE Like food and water, sleep is a physiological need vital to human survival and critical to human existence. Sleep loss can be additive and can result in a cumulative sleep debt. If we were to sleep for 2 hours per night less than we needed, then after four nights, our fatigue state would be similar to having had no sleep. The performance degradation after a single night without sleep can be quite astonishing
FATIGUE Sleep loss and fatigue can decrease physical, psychomotor, and mental performance, and can affect mood. A principal consequence of fatigue is an increased vulnerability to performance decrements. Like the effects of alcohol on performance, judgement and memory, fatigue can lead to a reduced safety margin and an increased potential for operational incidents and accidents.
FATIGUE Sleep loss and fatigue resulting from extended duty or altered work/rest schedules have been suggested as contributory factors in many accidents and catastrophes. Chernobyl Exxon Valdez Flying Tigers (Kuala Lumpur) Korean Airlines (Guam) American Airlines (Little Rock)
FATIGUE Sleep is a highly complex physiological process during which the brain and body alternate between periods of extreme activity and quiet. It is composed of two distinct states: REM - Rapid Eye Movement sleep NREM - Non-REM Sleep
FATIGUE During NREM sleep, physiological and mental activities slow (e. g. , heart rate and breathing rate slow and become regular). NREM sleep is divided into four stages, with the deepest sleep occurring during stages 3 and 4. There is usually very little mental activity during NREM stages 3 and 4. If awakened during this deep sleep, an individual may take some time to wake up and then continue to feel groggy, sleepy, and perhaps disoriented for 10 -15 minutes. This phenomenon is called sleep inertia.
FATIGUE REM sleep is associated with an extremely active brain that is dreaming, and with bursts of rapid eye movements (probably following the activity of the dream) During REM sleep, the major motor muscles of the body are paralysed, although some twitching may occur. If awakened during REM sleep, individuals can often provide detailed reports of their dreams.
FATIGUE (Dawson, 2006)
FATIGUE Factors Affecting Sleep Prior sleep/wakefulness Age (much less REM as you get older) Medical conditions (eg. Apnoea, Twitching Leg) Medications Alcohol Environmental/work conditions Time Zone Passage Circadian phase
The Circadian Rhythm
FATIGUE Trans-Meridian Passage When we transit across time zones the circadian cycle is either artificially shortened or lengthened, depending on whether we travel East or West. It can often take several days for the body to resynchronise to the new time zone, so we may naturally feel like not going to sleep when we should, or alternatively, sleeping at inappropriate times It can have substantial effects on the amount and quality of our sleep until the body adjusts to the new time zone
FATIGUE Fatigue affects us in the following ways: Forgetfulness and unreliable memory Reduced cognitive ability Loss of flexibility Poor decision making (especially unbounded decisions) Slowed reaction time and decreased ability to perform skills Reduced attention and vigilance / fixation Poor communication (a fundamental core of CRM) Reduced situational awareness Apathy and lethargy (can’t be bothered) Bad mood (affects crew cooperation and teamwork) Nodding off / microsleeps Physical fatigue (Cabin Crew on their feet all day)
FATIGUE The following graphs show the results of some experiments on fatigue from the University of South Australia Sleep Research Centre. They compare the effects of sleep deficit with the effects of alcohol
FATIGUE Effects of fatigue: (Dawson, 2006)
FATIGUE Effects of fatigue: (Dawson, 2006)
FATIGUE Effects of fatigue: (Dawson, 2006)
SYMPTOMS OF FATIGUE PHYSICAL SYMPTOMS MENTAL SYMPTOMS • Yawning • Heavy eyelids • Eye-rubbing • Head drooping • Microsleeps • Difficulty concentrating on tasks • Lapses in attention • Difficulty remembering what you are doing • Failure to communicate important information • Failure to anticipate events or actions • Accidentally doing the wrong thing • Accidentally not doing the right thing EMOTIONAL SYMPTOMS • More quiet or withdrawn than normal • Lacking energy • Lacking motivation to do the task well • Irritable or grumpy behaviour
Countermeasures Low fat, high protein; fruits and vegetables; whole-grain breads and cereals At least 2 litres of water per day Regular exercise Long naps, 3 -4 hours, can significantly restore alertness for 12 -15 hrs Short or “power” naps of 10 -30 minutes can help restore alertness for 3 -4 hours. Caffeine can help counteract noticeable fatigue symptoms if awake for 18 hours or less Rotate flight tasks and converse with other crewmembers Keep the flight deck temperature cool Move / stretch in the seat, and periodically get up to walk around the aircraft if possible Gradually shift times for sleep, meals, and exercise to adjust to a new time zone
Countermeasures Wake-up and go to bed at the same time every day to avoid circadian disruptions. Use the bedroom only for sleep and sex and not for work. Establish a consistent and comforting bedtime routine (i. e. , reading, taking a hot shower, and then going to bed). Perform aerobic exercise every day, but not within 2 h of going to bed. Make sure the bedroom is quiet, totally dark, and comfortable. Keep the sleep environment cool (16– 18°C if you are covered). Move the alarm clock out-of-sight so you cannot be a clock watcher. Avoid caffeine in drinks and other forms during the afternoons/evenings. Do not use alcohol as a sleep aid (it may make you sleepy, but you will not sleep well). Avoid cigarettes or other sources of nicotine right before bedtime. Do not lie in bed awake if you do not fall asleep within 30 minutes
Traditional Fatigue Management Systems Generally speaking FMS have been based on prescribed hours of service. These are often laid out or suggested by regulatory authorities, or in negotiated employment agreements. Common examples include: CASA CAO 48. 1 NZCAA AC 119 -2 UKCAA CAP 371 EU – OPS 1 FTL FAA FAR PART 121
CASA CAO 48. 1
NZCAA AC 119 -2
UKCAA CAP 371
THE FATIGUE RISK MANAGEMENT SYSTEM
FRMS The concept of “defences in depth” stems from the work of James Reason (1997), and applies to the original battlefield philosophy of multiple lines of different types of defences to the process of safety management. According to this model, the most effective way that an organisation can manage a specific hazard, is through the development of multiple layers of defences.
FRMS Rather than relying on compliance with prescriptive hours of service (HOS) rulesets in order to manage the safety-related risks of fatigue, an FRMS develops and employs multiple strategies to manage fatigue, such that each strategy forms an additional layer of defence against fatigue.
Multiple Defences against a Fatigue as an Identifiable Hazard (Dawson and Mc. Culloch, 2005)
Self Assessment – Individual Fatigue Likelihood Scorecard (IFLS) FATIGUE ASSESSMENT STEP 1: Sleep in prior 24 hours Sleep ≤ 2 h 3 h 4 h 5+h Points 12 8 4 0 STEP 2: Sleep in prior 48 hours Sleep ≤ 8 h 9 h 10 h 11 h 12+h Points 8 6 4 2 0 STEP 3: Hours awake since last sleep (at end of shift) If sleep in Step 2 is greater than hours awake, points = 0. If less, add 1 point per hour awake greater than sleep in Step 2. SCORE Example AKL – RAR RTN 1815 – 0530 Duty 8 hours sleep last night 4 hours sleep previous night Wake up at 0730 Total points to determine your score WHAT ACTION DO I TAKE? SCORE CONTROL LEVEL 1 -4 Keep an eye on yourself 5 -8 Look out for each other 9+ Go back to bed STEP 1 = 0 STEP 2 = 0 STEP 3 =10 TOTAL = 10 Go Back to Bed!
BEHAVIOURAL MONITORING KEEP AN EYE ON YOURSELF LOOK OUT FOR EACH OTHER • Monitor your alertness • Look for symptoms of fatigue • Consider use of in-flight rest where available • Look at food intake and hydration • Consider use of caffeine • Exposure to light may improve alertness • Communicate your state to other crewmembers • Assess your ability for duty • Find an opportunity for rest when available • Cabin Crew consider reallocation of positions and service tasks • Flight Crew consider PF / PM • Submit a Fatigue Report Form
FRMS Within the VB / PB FRMS there are three groups set up to oversee and run the FRMS: The Roster Working Group Committee The Crew Alertness Study Team The Governance Committee
Human Factors Training Implications Like Stress, Fatigue has an adverse effect on every other facet of human factors eg. - Communication Cooperation / Teamwork Workload Management Information Processing Decision Making Situational Awareness Leadership
Human Factors Training Implications Individual companies will make their own choices over what fatigue management scheme they elect to employ, however as Human Factors facilitators and developers it is important for us to recognise the criticality of fatigue and to do our best to enhance crew awareness of: Fatigue effects Behavioural signs of fatigue, and Fatigue countermeasures