CAUSES OF ERRORS
As stated previously there are a multitude of factors which can and will contribute to errors being committed: Here are some of them:
¨ Stress
¨ Fatigue
¨ Complacency
¨ Communication
¨ Ignorance
We shall address the more common, easily recognisable ones but, be aware that around every corner a new one is waiting to trap the unwary.
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STRESS
¨ Sickness absence costs to UK economy on average £11,000,000,000
¨ 30 - 40% of this is stress related
(C.B.I. 1994)
¨ ALCOHOLISM costs over £2.2 billion per year in terms of premature death, sickness absence, unemployment and N.H.S. treatment
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STRESS
What is Stress?
It has been said that stress is 'a reality like love and electricity - unmistakable in experience but hard to define!' Research has shown what stress is not
¨ Stress is not nervous tension
¨ Stress is not the discharge of hormones from the adrenal glands (the common association with adrenaline and stress is not totally false but the two are only indirectly associated)
¨ Stress is not simply the influence of some negative occurrence - stress can be caused by quite ordinary, even positive events, such as a passionate kiss
¨ Stress is not entirely a bad event; we all need a certain amount of stimulation in life and most people thrive on a certain amount of stress
¨ Stress does not cause the body's alarm reaction which is the most common use of the expression - what causes stress is a Stressor
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OCCUPATIONAL STRESSORS
Most if not all of us will recognise and readily relate to the following list of stress factors:
NEW WORK PATTERNS
NEW TECHNOLOGY
PROMOTION
RELOCATION
DEREGULATION
DOWN SIZING
JOB DESIGN
BOREDOM
NOISE
TEMPERATURE
INCREASED COMPETITION
LONGER HOURS
REDUNDANCY
EARLY RETIREMENT
ACQUISITION
MERGER
MANNING LEVELS
INSECURITY
LIGHTING
ATMOSPHERE/VENTILATION
PRESSURE
Pressure at work to complete the job is part of stress which motivates us to do the job. We all know that if we have two weeks to do a 2 hour job, it is likely that we will do the job on the last available day. WHY? There was no pressure (Stress) to complete the job until the last day when you will see most of the pressure to do a job comes from within ourselves. The boss may say "I need the aircraft by 5 pm", but if the timescale is unreasonable and you don't say anything, then YOU, not the boss, are responsible for the pressure. The monkey on your back is yours because you have accepted it.
How to deal with pressure
Since pressing is a form of stress, the same advice applies.
¨ Stop and assess the situation
¨ Look at the situation rationally
¨ What is the reality of the situation? Can I safely complete my work on time?
¨ Have I communicated my concern in a concise and rational way?
¨ What is the worst thing that can happen to me?
Listen to your rational mind
¨ Has this happened before and what can I do better?
¨ What is the best rational plan
Act
¨ Speak up and ask for help or extra time as required
Often the error of pressure is due to an error of not communicating properly and trying to make do.
LACK OF AWARENESS
Lack of awareness, differs from lack of knowledge in that it occurs to engineers who often are very knowledgeable but fail to reason the possible consequences to what is normal good maintenance practice.
For example: An engineer mounts a fire extinguisher on a bulkhead as per normal maintenance practices, but fails to realise that in a crash, the person sitting in front of the bulkhead will remove the extinguisher with his head!!
It is not easy to be aware of all the consequences of a maintenance action, yet, particularly when one modifies anything on an aircraft, one must work to examine all possible outcomes.
A court of law is no place to explain why it is that you did not realise.
COMPLACENCY
Self-satisfaction accompanied by a loss of awareness of the dangers
Because of the repetitive nature of a lot of aviation maintenance work, complacency is an ever-present danger. As a person becomes complacent his stress level, for that task, decreases and with it his performance. A greater stimulus will be required in order to obtain a response.
With complacency can come Expectancy, where the AME will often see what he expects to see and not what is actually there. If other factors are also present such as fatigue, resources and stress (from a different source) then the chance of an error becomes very real.
The error of complacency can be lessened by:
i) Always following the checklist or work sheet: ie don't attempt to do work from memory.
ii) Be aware of the danger of complacency and tell yourself: "Today I am going to find a crack" or whatever.
Awareness is your strongest advocate in preventing complacency.
DISTRACTION
Meaning:
Draw one's attention away, Confuse
Distractions are a common occurrence anyway yet, if they occur in a critical phase of our work, they can have disastrous consequences. Distraction is one of the main reasons that an engineer fails to secure NUT "B" or a control cable or other critical part. Psychologists say it is the number one cause of forgetting. Often after an error has occurred, the engineer will be at a loss to explain how it happened. If other factors are present such as fatigue and stress, then the likelihood of an error occurring increases.
Prevention consists of awareness of the problem and the use of safety nets such as:
¨ proper use of detailed check lists
¨ flagging incomplete work
¨ witness marks
¨ dual or independent inspection
¨ going back three steps, ie return to a "known" point in the procedure.
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FATIGUE
Fatigue is the body's normal reaction to a physical or mental stress of prolonged duration. Its onset is insidious and the symptoms are not always recognised until the person has reached a high degree of fatigue. There are two types of fatigue:
Acute Fatigue:
is the result of intense physical or mental activity at a single task. It is of short duration, measured in hours, and is cured with a good night's sleep.
Chronic Fatigue:
is caused over a period of time and takes much longer to recover from. Each person has a personal level of ability to withstand fatigue which slowly diminishes as the person ages.
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Causes of Fatigue:
Some of the things that can induce fatigue are:
i) Long hours of labour of any type, physical or mental, but the harder the labour, the sooner the fatigue.
ii) Lack of sleep due to time to or inability to, sleep. If one can not sleep, it likely is due to stress, but physiological factors can play a role. Pain due to sickness or injury or simply a disruption of one's circadium rhythm ie jet lag.
iii) Stress of high intensity and/or long duration will induce fatigue.
iv) Large temperature variations, hot or cold, will induce fatigue. Temperatures in excess of 90 deg F (32C) can lead to heat exhaustion while temperatures below 50 deg F (10C) without proper clothing, can lead to hypothermia.
v) Noise if above the 80 dB mark for long duration will cause fatigue. Exposure to loud noises without proper hearing protection is a self correcting problem because, in time, you will no longer hear the noise (or any other noise) and the damage cannot be reversed.
vi) Vibration can also cause fatigue. If for prolonged periods and of sufficient intensity, it will cause headaches and muscle discomfort. However unlike noise, vibration is not known to cause any permanent damage although "white hand" from chain saw vibration and rivet guns can become permanent if ignored long enough.
vii) Strong Lighting and to a lesser degree, poor lighting will contribute to fatigue. The normal symptom is a headache, and if bad or long enough, eyestrain.
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Symptoms of Fatigue
Because the symptoms come on slowly it is important that we come to recognise the symptoms and be aware of its effects. Often the fatigued person is unaware that he is fatigued until the symptoms and effects have become quite extreme, therefore:
¨ An Enhanced Stimulus is required in order to respond.
The person would require a larger crack in order to see it. The greater the fatigue, the greater the stimulus required.
¨ Attention is reduced
The person begins to overlook basic task elements.
The person becomes preoccupied with a single task to the exclusion of others.
The person begins to lessen his visual scan.
The person becomes less aware of poor performance.
¨ Memory is diminished
The person begins to have inaccurate recall.
The person forgets peripheral tasks.
The person begins to revert to "old" habits.
¨ Mood becomes withdrawn
The person becomes less likely to converse.
The person becomes less likely to perform low demand tasks.
The person becomes more distracted by discomfort.
The person becomes more irritable.
The person begins to develop a "don't care" attitude.
Persons who work a midnight shift should be particularly aware of the symptoms as most persons have a normal low (circadian rhythm-time of day effect) between 0300 and 0500.
Fatigue, as seen by its detrimental effects, can easily lead to a maintenance error, especially if the person isn't aware he is suffering from it.
Circadian Rhythms
As you well know, the human body has its ups and downs. One reason for this is shown in the diagram below.
Body Control Diagram 1
Bad day ------
Good Day
Most body functions are controlled between an upper and a lower limit. Every day of your life you ride this roller coaster. On good days, you go up and down without getting too close to your limits. On bad days, you push the limits.
Many body functions which affect how you feel are like this, including such things as blood pressure, heart rate, body temperature, and alertness, to name a few.
The body functions that follow this type of up-and-down rhythm are connected. For example, most people will feel alert and do their best work when their body temperature is on the up cycle. This is probably because "up" body temperature reflects heat being produced by the energy furnaces of the body. The more energy to go around, the more energetic you feel.
Shift work can throw you off your rhythm in several ways. It can initially increase the ups and downs of your cycle and then, as you adapt to the new schedule, your rhythm will settle down again.
One of the keys to coping with shift work is to decrease the time it takes to resettle your body rhythms.
Shift work can throw your rhythms off cycle by changing the timing of your ups and downs. This can affect how you feel at different times of the day. It can also affect how you feel compared to someone else.
SHIFT WORK
Have you ever noticed how some people seem to breeze through shiftwork with little difficulty while others have a hard time? There are certain individual differences that have been shown to cause these different reactions to shiftwork. Even if you don't work on shifts, you might find that the information is useful anyway since we all occasionally experience the sleepless night or stressful day not unlike that experienced by shiftworkers.
Approximately 23% of all workers in the service sector work on shifts. Not all shiftwork creates difficulties, but some, especially 24-hour-a-day, 7-day-a-week operation, can create problems such as poor quality of sleep and disruption of daily biological rhythms.
Accordingly, the two major complaints from most shiftworkers are: lack of sleep and fatigue. But some individuals adapt readily to shiftwork while others manage to get by and still others can never adjust. A look at some of the reasons behind these individual differences in adaption will highlight steps that may be taken to improve our ability to manage the difficulties caused by shiftwork.
Individual Differences
Younger people apparently handle the physical demands of shiftwork better, but older workers handle the social and interpersonal problems more effectively, and extroverted, outgoing people seem to adapt more easily to shiftwork than introverted types. The remainder of this section will look at techniques that can be used by anyone, regardless of age or personality type, to help improve the quality of sleep and reduce fatigue.
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The Role of Sleep
Although the role of sleep is not fully known, it is generally agreed that sleep is not necessarily a passive state. there are a number of things that happen during sleep that do not seem to happen when we are awake. For example, body temperature, breath rate, heart rate, and blood pressure all drop during sleep, while the secretion of human growth hormone and other anabolic hormones (hormones that are involved in the cell building process) seem to increase.
Thus the role of sleep may be to serve a rebuilding function by restoring certain enzymes and chemicals needed in our bodies. However, it is possible that not all of sleep is necessary for restoration. Sleep researcher James Horne suggests that there are two sleep drives, the first being "obligatory" sleep comprising the first five hours or so. The second sleep drive is "facultative" and probably serves to pass time during the early morning hours when there is nothing to do anyway.
In other words, Horne suggests that if we normally sleep eight hours then the last three hours of sleep really only pass time. The main work of sleep is done after approximately five hours. so even if we don't get a full night's sleep, chances are we are getting enough to recharge our systems.
Many of us who experience sleep deprivation on a continuous basis, however, might not agree. Five hours sleep per night does not seem to be enough, especially if we usually sleep longer. We could, as Horne suggests, practice getting by with only five or six hours of sleep per night, but once we establish a pattern of sleep, it is often hard to break.