Introduction
The
UAS are widely used in the military and air force for intelligence,
surveillance and reconnaissance missions. More importantly, according to
authors Pedersen et al (2006), one-third of the U.S Military’s deep strike
aircraft are to be remotely piloted by 2010. The operations of UAS involve a
group of highly skilled personnel such as pilots, payload/ sensor operators,
maintenance engineers and technicians. In view of the versatility of UAS operations, they are required to perform shift works. To understand the impact
of shift works on crew’s performance, a study had been carried out by Air Force
Research Laboratory. Study revealed that shift workers are particularly
vulnerable to increased sleepiness, chronic fatigue, stress and decreased
alertness and performance both on and off the job (Hossain et al., 2004). As a
result, it is important to systematically and quantitatively evaluate the
impact of shift work from the human factors perspective and also the
understanding of fatigue, stress and circadian rhythm which affecting
performance (Thompson, Lopez,
Hickey, DaLuz, & Caldwell, 2006)
Fatigue
Fatigue is synonymous with tiredness. It is caused by
long hours, sleep cycle interruptions, overwork, circadian dysrhythmia and also
boredom (Orlady & Orlady, 2015) . More importantly,
fatigue causes impairment of judgment and decision making mechanism. Excessive
fatigue is a serious problem in aviation, especially for the flight crews in
the aircraft cockpit. Same authors highlighted two characteristics of fatigue.
As fatigue develops, it retards the timing of motor responses. Also, the
subject compromises accuracy and performance and willing to accept substandard.
Needless to say, both factors lead to inefficiency and compromise productivity.
In fact, elimination of fatigue is nearly impossible in manned and unmanned
aircraft operations.
Stress
In physical world, stress is created when a person acts
upon conflicting forces. Stress can be acute or chronic. Acute is caused by
temporal situation. Chronic is a prolonged life event. Stresses contribute to
performance. Moderate stress is actually a stimulation for greater performance.
On the other hand, excessive stress lead to unpleasant psychological and physiological
symptoms such as fear, anxiety, sweating and fatigue (Orlady & Orlady, 2015) . From the study, level
of stress varies with each individual, time and environment. The environmental
stresses are heat, noise, and vibration, low and high humidity. Occupational
and domestic stresses are associated with job and daily living. Most of the
times they are chronic and difficult to quantify such as death, divorce, job
change, retirement and pregnancies.
Circadian Rhythm
Circadian rhythm refers to body rhythms according to
earth’s rotation time of 24 hours. Individual variations range from 24 to 27
hours. Circadian cycle is regulated by entraining agents called ‘zeitgebers’ which are sensitive to
light. The cycle is important when associate with the human’s sleep and its
pattern. Sleep is vital to one survival. In fact, sleepiness degrades human
capability and impairs judgment. It is vital for shift workers to realize sleep
loss can be acute and cumulative leading to sleep debt. Moreover, sleep loss adversely
affects waking performance, vigilance and mood (Orlady & Orlady, 2015) .
It is important to design a shift work roster considering
the psychological and physiological aspects and to realize the impacts of
fatigue, stress and the effect of circadian rhythm towards shift worker. The
feedbacks from the crews on 6 ‘ON’ 2 ‘OFF’ shift pattern were insufficient rest
after night shift and 6-day working pattern compromises family time. Some
complained they have difficulty sleeping after clock-out at 8 am. To improve
the situation, alternate shift pattern has been suggested. Crews are required
to work 4 days and a day off for ‘day shift’ and ‘swing shift’. To improve
sleep quality, crews are given 2-day off after ‘night shift’. For long term
improvement, it is important to provide formal education and training on sleep
hygiene, alertness management, and coping strategies to shift workers and
schedulers. In addition, to apply science-based shift scheduling techniques
when developing manpower requirements and developing duty time and crew rest
requirements. UAS operations are forecast to become an ever larger portion of
military aviation, increased attention should be devoted by the research
community to developing tailored fatigue countermeasures for the shift
work-prone UAS environment (Thompson et al., 2006).
Reference:
Hossain, J. L., Reinish, L. W., Heslegrace, R. J.,
Hall, G. W., Kayumov, L., Chung, S. A., Bhuiya, P., Jovanovic, D., Huterer, N.,
Volkov, J., & Shapiro, C. M. (2004). Subjective and Objective Evaluation of
Sleep and Performance in Daytime Versus Nighttime Sleep in Extended Hours
Shift-Workers at an Underground Mine. Journal of Occupational and Environmental
Medicine, 46, 212-226.
Orlady,
H. W., & Orlady, L. M. (2015). Human Factors in Multi-Crew Flight
Operations. Burlington: Ashgate.
Pedersen, H. K., Cooke, N. J., Pringle, H. L., &
Connor, O. (2006). UAV Human Factors: Operator Perpectives. Advances In Human
Performance & Cognitive Engineering Research Vol. 7.
Thompson, W. T., Lopez, N., Hickey, P., DaLuz, C.,
& Caldwell, J. L. (2006). Effects of Shift Work and Sustained Operations:
Operator Performance in Remotely Piloted Aircraft. Brook City: Air Force
Research Laboratory.
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