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.
ChernobylExxon ValdezFlying 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 EMOTIONAL 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
• 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 RISKMANAGEMENT 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) rule-sets 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 McCulloch, 2005)
Self Assessment –Individual Fatigue Likelihood Scorecard (IFLS)
FATIGUE ASSESSMENT SCORE
STEP 1: Sleep in prior 24 hoursSleep ≤ 2h 3h 4h 5+hPoints 12 8 4 0
STEP 2: Sleep in prior 48 hoursSleep ≤ 8h 9h 10h 11h 12+hPoints 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.
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
Example
AKL – RAR RTN 1815 – 0530 Duty
8 hours sleep last night4 hours sleep previous night
Wake up at 0730
STEP 1 = 0STEP 2 = 0STEP 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
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
Human Factors Training Implications
Questions?