This essay gives an overview of the literature on the topic, discusses the findings of the literature and reason to think of the main effects of stress and possibilities to avoid the human error due to stress of a pilot. It summarizes the current state-of-the-art regarding ‘The influence of stress on the performance of pilots in aviation'.

1. THE INFLUENCE OF STRESS ON THE PERFORMANCE OF PILOTS
IN AVIATION
AMSTERDAM, OCTOBER 2017
ALLARD SYM SPRENGER
Abstract
The most aviation accidents are caused by the presence of a human factor, since human factors can cause errors. These
human errors can occur with pilots and therefore lead easily to accidents. A cause for an error of the pilot can be stress.
This essay reviews articles related to this topic to discuss the findings of the literature and to think of the main effects of
stress and possibilities to avoid the human error due to stress of a pilot. It summarizes the current state-of-the-art regarding
‘The influence of stress on the performance of pilots in aviation.’
Introduction
On the 6th July 2013, an Asiana Airlines Boeing 777-200ER flight 214 from Incheon International Airport near Seoul,
South Korea, to San Francisco International Airport (SFO) in the United States had to do a visual approach since an
automatic landing was not possible. The aircraft approached too slow and low and crashed on final approach into SFO.
Three passengers died and almost 200 people were injured. The pilot flying was an experienced pilot, but a trainee on the
B777 and almost 10 years without flying on SFO. During investigation on the crash, the pilot flying as well as his instructors
mentioned he was 'stressed' about the landing on forehand. The pilot reacted poorly to the stress that he experienced and
this resulted in a terrible event. This example is a good reason to better investigate and develop the impact and influence
of stress on human performance especially now the world of aviation is expected to grow fast and with that more aircraft
movement is coming.
The increasing amount of air traffic will lead to more accidents. Therefore, it is important to increase the level of safety.
The level of safety can be increased in mechanical and manual components. The manual components can be increased by
attempting to reduce the human error in the aircraft system. The human factors & safety division within the aviation
industry is already seriously developing regarding the statement of the influence of stress on pilots in aviation accidents.
This essay is written to give a recapitulation of the current state-of-the-art regarding ‘The influence of stress on the
performance of pilots in aviation.’
The importance of this topic is clearly because of the increasing role of human factors in the improving technological
systems as in aircraft. Since the role of humans in the aviation industry is well-known, the aircraft systems deal with the
human factor by integrating solutions for these human errors into the aircraft design and systems. So, aviation accidents
can be caused by human error in much cases and these human errors can be caused by stress of a pilot.
Therefore, the overview extends the aspects according to the definition of stress, the symptoms of stress, the stress on pilots
and the effects, the effect on pilot performance or behaviour and functioning, stress as crucial component of pilot
performance and how stress can be avoided according to research. So, the present knowledge about the influence of stress
on pilot’s performance can be used to integrate solutions in aircraft systems to deal with these influences.
This essay includes a literature review about the most recent articles from on scientific base related to the topic statement.
The used literature is about stress in general, how stress relates to aviation, human factors, the monitorization of stress, the
symptoms, how pilots commute, pilot performance under stress and the empathic accuracy, cognitive concepts, human
performance related to human machine interaction, and the effects of stress on flight performance. The review of this up-
to-date literature will lead to an overview of the newest insights related to the topic.

2. Literature review
Wat is stress?
Stress is defined as ‘A state of mental or emotional strain or tension resulting from adverse or demanding circumstances’.
This is a commonly accepted definition. Therefore, stress can be defined as an unwanted diversity between demand and
resources or response capabilities where failure is a consequence of the unrecovered demands. Where the ability to succeed
always depends on the present person´s age, mood, experience etcetera. A statement about stress by Richard S Lazarus is
that "Stress is a condition or feeling experienced when a person perceives that demands exceed the personal and social
resources the individual is able to mobilize."
Understanding the stress on human performance is important, because it creates the ability to predict the behaviour and
functioning of a pilot’s performance in the future. Stress can be broken down in a division. This division can be explained
with several descriptions. There are two types of stress. The first one is eustress which is beneficial for performance,
because it makes people alert. The other one is distress which leads to poor decision making, judge errors, confusion, loss
of situational awareness, and not being able to cope with a certain workload. Eustress can be helpful until de stress level
increases to much and it becomes distress. Than performance will degrade. Besides distress and eustress, there are more
used descriptions that indicate this breakdown and they are mentioned later. Stress can also occur during a task or before a
task. Stress before a task is because of the prevenient worry about the upcoming task.
Symptoms of stress on pilots
The symptoms of stress can be monitored in many ways. Stress is monitored by voice in correlation with heart rates. This
is done by using the voice of the pilots in combination with the heart rate data in a full simulator situation. This research
method can be found useful, because the voice is a good signal source, since the voice of the pilots can be captured in a
gentle way without being intrusive, what could influence the pilots. The combination of voice and heart rate gives more
characteristics than only voice or heart rate and can be subdivided in many kinds of stress by measuring the speech. Stress
is also monitored by self-reporting, subjective measures, objective measures and eye tracking. Another interesting tool is
a pressure/grip measurement. Analysing the hierarchical regression showed response in form of a threat related to poorer
performance and disrupted attentional control of the pilot due to a rising level of stress. So, this is a process that influences
the amount of stress and therefore the performance.
The stress on pilots and the effects
In a research, the effect of flight factors on pilot’s stress at final approach and landing is tested in a simulator with heart
rate registration and task load indicator. These effects of stress can be seen in symptoms. The symptoms for stress are seen
in physical, emotional, behavioural, and cognitive effects.
Important cognitive concepts in aviation are given as well. Cognitive constructs can affect the behaviour of pilots in the
cockpit. The half of all fatal accidents between 2005 and 2014 happened during approach or landing. And another 1/8th
during take-off and initial climb. Stress is a main reason that causes psychological imbalance, because of physical, mental,
and emotional demands. The stress stimulators in a cockpit are radio communication noise, alarms, warnings, temperature,
engine noise, vibrations, small workspace, air quality, lighting. Besides that, the need of high alertness is a major stress
stimulator.
The stress level on pilots is the highest at take-off and landing. Stress at home results in a higher stress level during duty.
Time and workload of flying an aircraft in combination with the flying itself leads to an increasing level of stress. The
stress make that the pilots must rely on their heuristics, because of the negative influence of stress on their decision-making
ability.
The effects of stress are related with landing performance and glidepath tracking performance. The level of stress increased
together with lower performance when pilots flew over populated areas as well as when they flew under an angle during
approach. A decreasing amount of stress can be managed by examine new flight procedures for pilots on stress.
The voice and heart rate measurement results lead to the finding that cockpit crew have simultaneous moments of tension
and therefore the whole cockpit crew experiences a higher level of stress at the same time.

3. The effect of stress on pilot performance (behaviour and functioning)
The performance of pilots is retrievable in the behaviour and functioning of pilots. Pilots have a maximum capability for
performing. This maximum capability will be higher than the level of stress and will therefore not get on the same level in
a normal situation. This gap is a safety margin. The capability decreases with the length of the duty time and therefore the
safety margin will decrease even when the level of stress remains constant.
A challenging situation can lead to stress that can improve the quality of performance, but a threating situation can lead to
interruptions to attentional control and poorer performance and therefore a reduction of the full manual control of an
aircraft. Challenging and threating states are predictors for the task performance in aviation. Higher demands than resources
lead to a threat respond to stress and gives poorer performance than when resources are higher than demands and therefore
lead to a challenge respond to stress. A threat response leads to distraction of what they pay attention to and what not.
The empathetic ability of a pilot changes in a stressful situation. Empathy is the key skill of social situational awareness.
Stress has an influence on social cognition. The empathy of pilots and stress can impact each other in a cockpit. Since stress
is a response of an organism when demand is higher than capacities or resources. The amount of stress per flight phase
differs. The most stressful phases are go-around, bird strike, and landing. During a go-around, the pilots are not aware of
the stress level of their fellow pilot. The pilot flying and pilot monitoring are not certain regarding their colleague’s stress
level, especially when a situation is stressful for themselves. A reason for the low empathy is because of the changing
cockpit crews, since they do not work together often.
Another effect is because of the movement pilots should make to get on the job. This influences the safety of their
performance, since their performance is influenced by the amount of stress. Pilots get stressed for morning flights, because
of the possibility of missing their alarm. They worry about not arriving on time (duty) which lead to stress. Stress on
forehand of a flight makes the pilot more fatigue in an early stage.
Stress as crucial component of pilot performance
The envelope of human performance should develop as the cockpit human machine interface design is changing. Through
the more complex systems, the cognitive demand gets higher and makes the proper functionality of the human factor more
crucial in the system. The cause of a human error is important to know, because it is the main reason of accidents in aviation
nowadays. The envelope of human performance includes stress as one of the nine components. Some other components
are fatigue and workload. These nine components cooperate, since they are dependent. If the stress level increases, the
workload should decrease to let the pilot perform sufficient. If the stress and workload level are high, the pilot will not be
able to perform as expected. A response to stress is that the autonomic activity gets bigger. Two types of stress are acute
and chronic. Acute is caused by a high task load which leads to lower decision making and communication performance.
Chronic stress is caused by a long stress-inducing situation at home or work. Stress leads to less attention, monotony and
less helping the environment to succeed. The stress assessment is done by a communication analyses, physiological analysis
and cognitive analyses.
How to avoid
Stress can be avoided by relieve factors which are physical and mental. Physical is eating well of get enough sleep and
mental is having sufficient confidence for example. The emotional aspect is hard to control, but training can increase the
ability of a pilot to deal with stress or handle stressful situations better. Avoiding stress from another perspective is to
improve the system and interaction between the human and machine

4. Discussion of the findings from the literature review
The literature gives an insight on the present research and view of the influence of stress on aviation pilots. The different
articles are dividing stress in two groups, but not in the same way. This different dividing leads to other concepts of forms
of stress. Stress should be seen as a useful reaction of the human body to perform better in particular situations until a
certain extent where it is counteracting. The given symptoms for stress in the articles lead to some different views as well.
The speech of pilots and heart rate are good measurement techniques which are used very often and even in combination
to see the correlation, which gives a better insight. Self-reporting seems a good measurement, but it can occur that pilots
will not be honest and in that case the results are not reliable. Subjectivity can be influenced as well by the researcher or
participant. The difference between the articles on the way they look at the reason of stress on pilots is where stress comes
from. Stress can arise during a job or it can originate before their job, as stated. These two types are in line with the division
of the stress and are both influencing the level of stress instead of just one of them. Not only the amount of stress that arises
due to a task, but the length of the duty plays a role in the increase of the stress level as well.
The performance level the pilots need to reach includes as a safety margin when the stress level is not too high. In a
challenging situation, this margin is sufficient to keep the pilot handle the task load. When a threating situation comes up,
a threat response leads to distraction of what they pay attention to and what not. That safety margin is not clear and very
personal. Even the present state of a human is influencing that margin, so it is not a considerable fact.
Better knowing a colleague pilot his stress level is useful to make sure he is still able to handle a certain task load and
therefore perform adequate. The focus is in one considered research on empathy of pilots and their reaction on that
observation. It was stated that flying in the same composition of cockpit crew more often should be an option to implement
in the airline flying system, because the empathy will rise if you know your colleagues better.
The amount of stress is indicated per flight phase and the articles are in line with that, but some focus only on those
situations as if stress appears out of the blue. A result was that the low empathy of pilots regarding their colleagues was
the changing cockpit crews instead of permanent, but this is not a good reason for not being empathic.
Stress is seen in a research as a component in the human performance envelope. This gives a good overview of the influence
of stress and the other components on the performance of a pilot. As the system in the cockpit gets more complex, the
human performance envelope should develop with it to maintain a good cooperative system between human and machine.
All the research is done by use of simulators to test their hypothesis, but a simulator does nog give real information about
the amount of stress, because the subconscious mind of the pilot knows that it is not real and therefore a stressful situation
cannot be simulated for one hundred percent. Therefore, certainly the voice analyses, grip measurement and observation
by researchers should be done in real flight to get accurate results.
All the research found in the articles is going about the presence and causes of stress, the indicators, the influence and just
for a small part about recommendation or discussion about how to implement a risk factor of stress or the avoidance. The
given measurement for avoidance is jumping to conclusions way to fast. The recommendations should be pointing to the
improvements of training and the improvement of the systems regarding the presence of a stress factor in the human
component that works in the system. Human performance and therefore possible errors are always part of the complex
system. This cannot be solved, but should be reduced as much as possible. The research must be used to learn from the
way people react.

5. Conclusions
To conclude, a summarization and evaluation of the discussed aspects of the literature review and discussion is given in
relation with topic of the essay about the main effects of stress and possibilities to avoid the human error due to stress of a
pilot. Stress is a main reason that causes psychological imbalance, because of physical, mental, and emotional demands.
Stress can arise during a job or it can originate before their job. These two are in line with the division of the stress and are
both influencing the level of stress instead of just one of them. Not only the amount of stress that arises due to a task, but
the length of the duty plays a role in the increase of the stress level as well. Stress should be seen as a useful reaction of
the human body to perform better in particular situations until a certain extent where it is counteracting. The stress
stimulators in a cockpit are radio communication noise, alarms, warnings, temperature, engine noise, vibrations, small
workspace, air quality, lighting. Besides that, the need of high alertness is a major stress stimulator. Stress is the highest
during take-off, landing, go/around and bird strike. Stress at home results in a higher stress level during duty too. Since
stress can be monitored in diverse ways the conclusion is that the voice in correlation with heart rates gives the most reliable
outcome. The used symptoms to discover the presence of stress are speech, heart rate, self-reporting, subjective measures,
objective measures, eye tracking, and pressure-grip measurement. The symptoms for stress are seen in physical, emotional,
behavioural, and cognitive effects. After the discussion, the heart rate, voice and eye tracking seem to be the most reliable
symptoms to use for investigating the presence of stress at pilots.
The margin between the ability to perform and the amount of handled stress is not clear and very personal. Even the present
state of a human is influencing that margin, so it is not a considerable fact. The stress make that the pilots must rely on
their heuristics, because of the negative influence of stress on their decision-making ability. The level of stress is
significantly higher when pilots fly over populated areas as well as when they fly under an angle during approach. Cockpit
crew have simultaneous moments of tension and therefore the whole cockpit crew experiences a higher level of stress at
the same time. The performance of pilots is retrievable in the behaviour and functioning of pilots. Higher demands than
resources lead to a threat respond to stress and gives poorer performance than when resources are higher than demands and
therefore lead to a challenge respond to stress. A threat response leads to distraction of what they pay attention to and what
not. The pilot flying and pilot monitoring are not certain regarding their colleague’s stress level, especially when a situation
is stressful for themselves. A reason for the low empathy is because of the changing cockpit crews, since they do not work
together often. Better knowing a colleague pilot his stress level is useful to make sure he is still able to handle a certain
task load and therefore perform adequate. A result was that the low empathy of pilots regarding their colleagues was the
changing cockpit crews instead of permanent, but this is not a good reason for not being empathic.
The cognitive demand gets higher as the cockpit human machine interface design is changing. This makes the proper
functionality of the human factor more crucial in the system, so the envelope of human performance should develop. Stress
is seen in a research as a component in the human performance envelope. This gives a good overview of the influence of
stress and the other components on the performance of a pilot. As the system in the cockpit gets more complex, the human
performance envelope should develop with it to maintain a good cooperative system between human and machine.
Since a simulator does nog give reliable results, the voice analyses, grip measurement and observation by researchers
should be done in real flight to get accurate results. Stress can be avoided by relieve factors which are physical and mental.
The focus should be on integrating solutions to degrade the influence of stress in training and system development or
improvement.
The given measures for avoidance is jumping to conclusions way to fast. The recommendation or or discussion about how
to implement a risk factor of stress or the avoidance of it should be pointing to the improvements of training and the
improvement of the systems regarding the presence of a stress factor in the human component that works in the system.
The research must be used to learn from the way people react, since human performance and therefore possible errors are
always part of the complex system. Excluding the stress component in the human factor envelope is not possible, so it
should be reduced as much as possible.

6. Relevance for practice and the Aviation Academy
The relevance of this essay is argumentative in view of the fact that the topic is about safety within the aviation industry
and that it still needs to be further investigated and especially solutions should be implied or improved. The aviation
academy can consider to spend a course on this topic within the safety theme to make students more aware of the influence
of this difficult kind of human factor within the aviation since it is a difficult to contain and difficult to solve problem.
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