Fatigue is a popular threat to aviation since it impairs alertness as well as impairing performance. It is defined as a non-pathological state that results in a decreased capability to maintain workload or function because of physical or mental stress. Fatigue is a term that describes a broad range of experiences from tired, or exhausted, to sleepy. There exist two major physiological phenomena that have been shown to cause fatigue. These include circadian rhythm disruption and sleep loss. Fatigue is a known normal response to numerous conditions common to operations of the flight due to loss of sleep, long duty cycles, and shift work. Fatigue has notable performance and physiological consequences since it is essential that all crewmembers of the flight remain alert as well as contribute to the safety of flight by their observations, communications, and actions. Adequate sleep is the only effective treatment for fatigue (Caldwell, 1997). The US commercial aircraft accident that occurred on the 18th of August in the year of 1993 in Guantanamo Bay, Cuba involving a DC-8 is an example of fatigue as a probable cause of aircraft accident. The airplane was destroyed by impact forces as well as post-accident fire. During this incidence, three flight members were seriously injured. Prevalence of visual conditions occurred and filing of an instrument flight rules plan had occurred (Strauss, n.d). The following is an analysis of the importance of sleep and the cause of sleepiness.
Sleep and Loss of Sleep
For proper physiological function, sleep is vital. Similarly to water and food, sleep is important for survival. When sleep loss occurs, sleepiness results. Similarly to thirst and hunger, sleepiness acts as the signal for the brain that sleep is required. Lack of sleep describes getting less sleep phenomenon than is required for maximal waking alertness and performance. Two hours of sleep are lost in a case where an individual requires sleeping for eight hours and only gets six hours sleep. Successive loss of sleep accumulates into a debt of sleep. An eight hours sleep debt can be acquired if an individual requiring eight hours of sleep gets only six hours a night for four continuous nights. It has been demonstrated in the laboratory that losing as little as two hours of sleep can affect performance as well as alertness negatively. The effects on performance are degraded situation awareness, memory, decision-making, and judgment. In addition, it slows the reaction time, reduces concentration that cause fixation, and the mood is worsened. The other effects associated include reduced work efficiency, reduced motivation, and increased variability of work performance, degraded crew coordination, and decreased vigilance. From about 3 to 5 am and 3 to 5 pm, the brain is programmed for two periods of maximal sleepiness every 24 hours (Battelle Memorial Institute, 1998).
Categories of Fatigue
There are three types of fatigue namely, physical fatigue, mental fatigue, and emotional fatigue. To begin with, physical fatigue defines the various physical issues like muscle soreness, tiredness resulting from inadequate sleep or illness, insufficient oxygen, and poor nutrition. Secondly, mental fatigue is linked to task demanding cognitive information processing, intense concentration, or other high cognitive skills. Mental fatigue is mostly present during night in pilot flying in Instrument Flight Rules. Mental fatigue can result from prolonged activity. Thirdly, emotional fatigue also called burnout represent the wearying effect of working under tasks that are psychological disagreeable. This kind of fatigue is evident when individuals begin complaining about being bored, tired, or consistent arguing at home or at work (Stokes & Kites. 1994).
Causes of Aviation Fatigue
The degradation of a person’s ability to carry out duty because of the deleterious effects of numerous factors over time can be categorized into numerous broad areas of causes. These broad categories include physical exertion, environmental factors, lack of familiarity, and excessive workload among others. May be the most easily identifiable cause of fatigue is excessive workload. Within the aviation environment examples of probable causes of excessive workloads that can cause fatigue include the workload added during takeoff as well as landing which has a powerful impact on short haul pilots who during a shift conduct many short segments. Such pilots have a greater percentage of time in these modes and thus build up fatigue over a period of given time than long haul pilots who take most of their time in cruise of lower workload (Kantowitz & Casper, 1988). Another example of cause of workload fatigue is the manual flight controls present mostly in aircrafts of older generations which have a high labor intensive needing more steps to conduct many tasks and are less intuitive mostly making use of visual or audio codes that are not intelligible immediately. Weather inclement is also a cause of workload fatigue during any flight phase and the general cognitive as well as decision making of flight.
Physical exertion is another cause of fatigue. Physical fatigue results from altitude effects in which case the capacity of physical activity is lower hence pilots are affected if they spend most of their time at the equivalent of 10,000 feet. The need to stretch as well as physical placement of control interfaces is required. Another cause of physical fatigue is the strain of staying seated in a fixed position for prolonged periods of time. The needs of crews outside the plane like conducting aircraft checks outside and walking between gates is also necessary. Fatigue can also be caused by the environment. Pilots who fly long haul must deal with changes in time zone and thus transformations in day or night cycles. The changes include humidity and temperature changes, elevated exposure to contagious diseases, disrupted as well as variable sleep patterns, variable work scheduling, and meal type’s variation.
Some of these environmental factors are experienced by short haul pilots in certain circumstances. Increased cognitive demand is largely unrecognized as a common source of fatigue. Mental constrains can result from problems associated with cognitive demand. When pilots are required to communicate in a different language other than their native language, they suffer from mental fatigue because of the linguistic barrier. The exposure to noise as well as vibration also causes fatigue when the exposure is prolonged (Cladwell, 2003).
Symptoms of Aviation Fatigue
There are numerous signals that flight crewmembers should take as alert for a dangerous situation when they find themselves flying under fatigue. These are the symptoms of fatigue which include, involuntary bobbing of the head, persistent yawning, eyes going in and out of focus, wandering or poorly organized thoughts, erroneous or missed performance of routine procedures, spotty near term memory, and degradation of control accuracy (Strauss, n.d).
The problem of inadequate sleep can be understood by understanding what sleep is. Four stages of sleep are known beginning with around 10 minutes of rapid eye movement sleep where the mind is active and twitching of muscles occurs at this time. The mind as well as the body slows down during the next three stages. After 45 to 75 minutes, an individual goes back to rapid eye movement stage. During several times through the night, individuals go through this cycle and interruption of any stage will render ineffectuality to that entire cycle. Disruption is one major cause of sleep deprivation of our internal light/dark cycle known as circadian rhythms. These are the biological clocks existing in our brains since times in memorial. They tell us that we should work during the day when it light and sleep at night when it is dark.
Changes in circadian causes an individual to attempt to sleep when their mind is wide-awake as well as force them to stay awake when their mind is yelling to go to bed. The most common causes of fatigue faced by pilots are long schedules and changes in circadian rhythms. This is because; little can be done to transform them. All of us are subject to these factors and the best defense is to have a limit of their effects by regulating the fatiguing factors in our proximity.
Nutrition and Diet
Coffee is the popular beverage among pilots. Coffee is a stimulant that causes a temporary increased alertness level. Its withdrawal is symptomatic of fatigue. Coffee is also a diuretic and as such, causes the body to release more fluids than its taking in thereby resulting in dehydration that can cause fatigue. A strenuous workout can similarly cause dehydration while there can be no argument against being in proper physical shape. The strenuous workout should be completed with adequate time for rehydration. Environmental conditions can also cause dehydration.
Nutritional intake is another factor. A pilot’s diet can be horrendous at times. Feeding is important as it keeps one energetic as well as improving the mood. This is because lack of adequate energy may cause a pilot to become hypoglycemic. Fatigue can result in a pilot with compromised feeding especially if the nutritional value of their diet is not considered. A healthier diet is preferable in the long term and may be achieved by packing ones food, receiving the company’s catered meals, or getting from the airport diner a healthy meal.
Environment and Illness
A pilot should not fly while sick. This is obvious but many individuals fly when they are still sick. Reporting the crew’s malady is made financially disadvantageous by many companies. Certain pilots believe that they are invincible and that they work better than most even when afflicted with a flu or cold. Some compensate with antihistamines because they know that they are impaired by an illness. The symptoms of the illness are alleviated by antihistamines but fatigue is increased by their nature. Individuals are doing their fellow crew members a disfavor by illness exposure and further increasing the likelihood of an error in operation due to fatigue. They maybe or maybe not involved in an accident although they can unwittingly be a contributing cause to one.
Noise and vibration, extreme temperature, flickering light, and hypoxia are other environmental concerns. Numerous less-experienced pilots will go out and have fun on exciting layover at their vitally required rest cost. To maximize productivity, certain companies stretch their employees’ rest needs to the legal limit of flight as well as duty time restrictions. Automation as well as long international flights reduces mental stimulus in addition to increasing boredom.
Prevention of Aviation Fatigue
FAA as well as ICAO recommends that individuals get sufficient rest, sleep in a cool environment, dark, and quiet, and also ensure quality sleep. Individuals should refrain from reading or working in bed as this would contribute to falling asleep issues. The bed should be related only to sexual as well as sleeping activity. If one desires to read prior going to bed, he or she should do it in a chair outside the bedroom and afterwards go to bed. To prevent circadian dis-synchronization, individuals should adjust their work shifts which can be attained by maintaining a consistent wake/sleep schedule even during days off. It is also crucial to avoid exposure to daylight from dawn to 1000 when on the night shift. One should wear sunglasses incase they cannot go to sleep prior the sun rise. When sleeping, the individual should consider wearing a sleep masks to prevent from any exposure to light. The quality of sleep is affected by exposure to light prior going to sleep. A light snack can be administered prior going to bed, although one should avoid sleeping too hungry or too full. Caffeine consumption should be avoided for about six hours before going to sleep. Coping with sleep deprivation during continuous operations or other times when it is hard to get a good night’s sleep requires napping.
Another prevention strategy is to maintain good physical health together with programs of regular fitness so as to enable the body to fight against the effects of fatigue. Natural sleep should be obtained in plenty. When treating fatigue, it is important to maintain a reasonable work schedule during waking hours. It does not make any sense to catch up on sleep and then during the day exhaust one self. An individual should ensure they eat properly in order to offer the body the fuel required to recuperate. One shouldn’t sleep overly long during the recovery period after 24 to 48 hours of sleep deprivation. This is because, the normal sleep/wake cycle could be interfered with and result into problems the following night. An individual should prepare for sleep as one would normally have when trying to sleep outside your normal bedtime.
Impacts and consequences of Aviation Fatigue
Aviation fatigue impacts the humans’ ability to carry out necessary roles particularly in commercial aviation. The general effect of aviation is the same despite the varying causes of fatigue. The ability to focus on necessary tasks is as a result of increasing levels of fatigue in addition to increased tendency to ignore secondary tasks, significant accidents as well as a tendency to concentrate on a single input source. The accidents resulting lead to loss of life or property. The aviation staff organization is also affected by fatigue as their availability is affected. This defects the ability of the airline to schedule staff confidently, inability to control an appropriate sized workforce, and the ability to react to transforming circumstances efficiently.
Diverse and insidious fatigues are the most precise forms. When the level of fatigue in a person is increasing, timing as well as accuracy degrades with reduced level of performance which accepted unconsciously without self-detection. Narrowing of attention happens thereby increasing the risk of human errors in any circumstance. Performance decreases as sleepiness increases and the consequences of relationships of such kind deteriorate during night hours. The skill of reasoning as well as of solving problems reduces at normal time while psychomotor skills are diminishing with an elevated rate of false responses. Fatigue reduces social interaction with others and loses group eventually or the level of team performance. For pilots operating an aircraft, this is extremely critical. The most highly skilled or motivated individuals will have their performance impaired by the biological limitations imposed by fatigue. Training or experience, or negation by monetary or other incentives cannot overcome the effects of fatigue (Signal, Ratieta, & Gander, 2006).
Counter Measures to Reduce Aviation Fatigue
Numerous counter measures are available similarly to the many cause of aviation fatigue. Excessive workload fatigue can be counter measured by increasing automation of systems in order to reduce the amount of manual processes needed by flight crews. Besides automation, there is redesigning of flight controls as well as indicators following placement ergonomic principles as well as form-function intelligibility which have been shown to decrease cognitive demands that could result into fatigue. Take-off, landing, as well as inclement weather will proceed to be fatigue periods inducing high workloads with the only currently available counter measures being organizational as long as human pilots are employed in commercial aviation. This organizational remedy would be to reduce flight hours flown by a crew in a shift on the basis of segment weather as well as length.
Clearly defined countermeasures are available for fatigue produced by physical exertion since it’s the most studied cause of fatigue. These are ergonomic studies as well as increased automation will proceed to reduce the pilots’ physical demands via improved placement of controls as well as the use of glass cockpit interfaces comprised of multiple modes. Appropriate scheduling could partially mitigate fatigue resulting from flight exercise requirements. However, the outside exercise can also be viewed as desirable as it offers required breaks from the relative immobility periods experienced by pilots. Fatigue caused by immobility can be minimized by short ergonomic breaks whereby pilots wake up and walk around during cruise. Aircraft pressurization could be relatively easily adjusted to other points of pressure to reduce its effects of altitude. To address general sleep disruption resulting from varying schedules, long term fixed schedules can be introduced to allow members to come up with a fixed cycle of activity over time. This may not be as effective for night shift crew members as a tendency to alter cycle is present during days off to accommodate social activities. Increased awareness as well as a conscious attempt to reduce the risks can be used to combat environmental effects like exposure to contagious as well as the effect of meal variation.
The detrimental effects of the environment can be reduced by placing crews on fixed routes by creating two environmental home bases over time. There are numerous ways in which cognitive fatigue caused by lack of familiarity can be addressed. One is by scheduling individuals hence allowing the development on inter-crew rapport as well as a framework of communications. Additionally, fixed route scheduling would be established to reduce the fatigue created when dealing with unfamiliar airports as well as routes by minimizing these occurrences (Cram, 2005).
Recommendations and Conclusion
Aviation fatigue has been revealed to be a hazard in flight operations especially in commercial ones. Three categories of flight fatigue have been found namely; mental, physical, and emotional fatigue. These categories affect the pilot depending on the different exposure as well as the different circumstance the pilot is in. Numerous factors increase the risk of developing fatigue in the commercial aviation environment. Among these are inadequate crew rest, disruption of circadian rhythm, inadequate restful sleep, and prolonged work schedules contribute to the potential for fatigue in aviation. When the control concerning rest is compared to be identified needs for restful sleep, it is evident that adequate restorative rest may not happen. Review of service hours/rest regulation, federal research activities, as well as airline company scheduling policies are required to correct existing systemic issues. To prevent fatigue, enhanced pilot training is also vital as well as recognizing when it happens so that effective countermeasure can be recruited. Doing so will assist to insure that pilots flying get adequate rest as well as staying alert thereby enhancing the safety of flight. Hence, it is the responsibility of both the pilot and his/her employer to curb the problem of fatigue in aviation.