Fatigue is major
human factors hazard because it affects most aspects of a persons' ability to
do their job and leads to human factors errors. In human factors, fatigue is
one of many individual factors considered a cause of human error such as
stress, personal events, etc.
Fatigue isn’t
just human factors hazard for aviation industry only. It’s a hazard for all
industries such as healthcare, construction, etc.
Do you know
what I mean by Hazard?
A hazard is a
condition or an object with the potential to cause or contribute to an incident
or accident.
What is fatigue?
Fatigue means a
physiological state of reduced mental or physical performance capability
resulting from sleep loss or extended wakefulness, circadian phase, or workload
(mental and/or physical activity) that can a person’s alertness and ability to
safely perform aviation safety related operational duties.
In this
article, I will further your knowledge about fatigue to help you to minimize
its impact. Furthermore, you will understand how it reduces persons' mental or
physical performance capability.
Fatigue did this
In 2003, during
the holy month of Ramadan in Yemen (sleeping is after 5:30 a.m.), one of our
loading workers was loading a Yemen Airways aircraft - a narrow body - which
was prepared for a scheduled flight.
A worker loaded
the passengers' luggage in the forward cargo hold, and as a result of waiting
to load the rest of the luggage, he slept in the cargo hold.
His colleagues
did not notice that he was sleeping in the forward cargo hold, and the cargo
hold door was closed, and the aircraft took off.
About 25
minutes after take-off, the captain heard three knocks on the roof of the lower
cargo compartment. So, the captain was surprised that the knocks were repeated
in different numbers. After evaluating the situation, the captain proceeded in
the same way – knocks - with changing the number. Then, he waited for a while,
he heard the same number of knocks from the forward cargo hold.
The captain
made sure that there was a person inside the cargo hold. The captain returned
to Sana'a Airport. While arriving, the door of the cargo hold was opened, and
the worker safely got off.
I met this
loading worker during my first job - as a secretary - in the security
department of Yemen Airways, I asked him
How did that
happen?
He replied
laughing “I was tired, and I did not sleep well."
Do you agree
with me that fatigue did this?
Difference Between Tiredness and Fatigue
To
differentiate between fatigue and tiredness, the tiredness that we feel is
often alleviated through sleep and rest. While fatigue is an extension and
continuation of tiredness without reducing it by sleep and rest.
So, tiredness
is a symptom of fatigue.
Fatigue Types
There are three
types of fatigue: transient, cumulative, and circadian:
(1) Transient fatigue
Is acute fatigue brought on by extreme sleep restriction or extended
hours awake within 1 or 2 days.
(2) Cumulative fatigue
Is fatigue brought on by repeated mild sleep restriction or extended
hours awake across a series of days.
(3) Circadian fatigue
Refers to the reduced performance during nighttime hours, particularly
during an individual’s “window of circadian low” (WOCL) (typically between 2:00
a.m. and 05:59 a.m.). [ref. FAA, AC no: 117-3]
Fatigue Symptoms in Adults
Fatigue can be
mental or physical. Emotional fatigue also exists and affects mental and
physical performance. I will list these fatigue symptoms:
A- Physical Symptoms
1) Chronic tiredness or sleepiness
2) Headache
3) Dizziness
4) Sore or aching muscles
5) Muscle weakness
6) Slowed reflexes and responses
7) Impaired hand-to-eye coordination
8) Appetite loss
9) Reduced immune system function
B- Mental Symptoms
1) Short-term memory problems
2) Poor concentration
3) Lapses of attention and vigilance
4) Impaired logical reasoning and decision
making, including a reduced ability to assess [impaired decision-making and
judgment].
5) Delayed reactions (sometimes).
6) Risk or appreciate consequences of
actions.
7) In some cases- hallucinations
C- Emotional Symptoms
1) Moodiness, such as irritability
2) Low motivation.
3) Feeling of isolation
4) Being annoyed
In addition,
increased errors while performing tasks.
Common Causes of Fatigue
There is a wide
range of causes that can trigger fatigue. Also, fatigue can be caused by
several factors working in combination.
I will categorize causes into four main
factors:
1- Medical Causes
E.g., Illness,
such as a thyroid disorder, heart disease, or diabetes.
Note. You should consult your doctor.
2- Lifestyle Causes
E.g., lack of
sleep, individual factors, alcohol or drugs, etc.
3- Workplace Causes
E.g., workplace
stress, shift work, poor workplace practices, etc.
4- Emotional Causes
E.g., mental
health problems, such as stress, depression, and grief.
Managing fatigue
Each person
first needs to understand what the underlying causes of fatigue. Second, he is
responsible for managing his fatigue levels. These are some tips for good
fatigue management.
1- Sleep well
Improve your
sleep, improve your life. Nine hours of sleep per night to recover from
accumulated sleep debt.
2- Eat well
Eat regular meals.
3-Improve your lifestyle
Manage your
daily activities and lifestyle to maximize rest.
4- Do Exercises
Do exercises
regularly for more deep sleep.
5- Balance between family and work
Especially for
those who are working on irregular schedules.
6- Report fatigue Issues
Help manage
fatigue hazards.
Summary
Fatigue is a
physiological state of reduced mental or physical performance capability. It
reduces alertness and often reduces a person’s ability to focus and hold
attention to the task being performed.
A fatigued
person is easily distracted, less able to concentrate, forgets things, longer
time to solve problems, has slow reaction times, etc.
Further
reading, we recommend:
1- ICAO Fatigue
Management Guide for Airline Operator.
2- Basics of
Aviation Fatigue, FAA, AC No: 120-100
3- ICAO doc
9966, Manual for the Oversight of Fatigue Management Approaches