Video embedded from YouTube on 16 August 2012
What is Stress and how Stress Relate to Aviation
According to Dr. Hans Selye, stress is defined as "any event which may make demands upon the organism, and set in motion a non-specific bodily response which leads to a variety of temporary or permanent physiological or structural changes". 
Richard S Lazarus simplified the above definition (commonly accepted definition) and stated 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." 
In aviation, accidents almost always occur in a sequence of mistakes made, like a domino effect. Stress is the finger that many times pushes the first domino into the rest causing the effect. In order to maintain safety in aviation, at least one of these dominos must be removed to avoid a dreadful accident. This is where all of human factor studies and hard work can come into play. Depending on what particular job a person is performing in aviation, they must take steps to avoid undue stress. Stress can be avoided by taking steps to relieve other possible factors. Physical factors such as getting plenty of rest, eating a balanced diet and drinking plenty of water while exercising regularly will help the body resist fatigue and stress. Mental factors are equally as important. Knowing one’s job well and being confident in the execution of job duties will equally reduce stress. The equilibrium of physical and mental factors does not completely destroy the stress factor, but it will make it manageable and thus safer for everyone.
Major effects of stress on the body and its symptoms
|Picture embedded from LessStress on 12 Sep 09|
The image above shows a complex process of how stress affects the different parts of the body.
To put it simply, the "victim" will experience the following main symptoms:
• Tense muscles, especially in the neck and shoulders;
• Headache or backache;
• Stomachache, nausea, vomiting, diarrhea or constipation;
• Tiredness or difficulty sleeping;
• Unusually rapid heartbeat;
• Shakiness or excessive sweating;
• Weight loss or weight gain;
• Clenched jaw or clenched teeth;
• Sighing or changes in breathing patterns; and,
• Decreased interest in sex.
• Frustration, irritability or anger;
• Depression or anxiety;
• Nervousness; and,
• Boredom or apathy.
• Abuse of alcohol, drugs or other substances;
• Marital problems;
• Binge eating; and,
• Self-destructive behavior.
• Forgetfulness, preoccupation and difficulty concentrating;
• Work mistakes and loss of productivity;
• Excessive worry;
• Decrease in creativity; and,
• Loss of sense of humor
2 Different Types of Stress
Contrary to popular belief that all stress is negative, stress can either be good (Eustress) or bad (Distress). 
- Eustress can harness better performances and provide the incentive for aviation personnel to achieve the task, to train harder to improve their standards to become the best in their job.
- Distress on the other hand, affects people by bogging them down, causing them to lose focus doing time critical tasks in their area of work leading to accidents.
These are manifested in the following manner:
- Poor decision making
- Loss of situational awareness
- Make errors of judgement
- Become confused
- Unable to cope with increase in workload
- Absenteeism from work
Model Of Stress and Coping
This model below illustrates the processes which causes someone to develop stress.
Model of stress and coping
Link between stress and performance
|Picture embedded from LessStress on 12 Sep 09|
By analyzing the graph above, Eustress is depicted with performance increasing till a plateau, but if the increasing stress is left unchecked, distress will occur, leading to a breakdown of performance.
This is because at low levels of arousal stress, the body's attention mechanisms are not really active but as the stress level increases, we are more and more attuned to the environment and will react optimally and accordingly due to task complexity. However, at increasingly high levels of stress, degradation of performance occurs because with higher arousal, we tend to focus sorely on the main task, ignoring other peripheral information, contributing to errors.
Hence based on the graph, from a pilot's perspective, at critical junctures of flight such as take off and landing, it would be best that pilots are at optimal performance.
However, while cruising in flight, being in the middle of the upward portion of the curve would be sufficient although not at such a point that the pilot is under-aroused that important things like heading changes or reporting points are missed.
As such, the aim when performing their tasks is for all personnel to maintain the stress at a manageable level, below the fatigue point but not so low that the person is not alert.
Researchers have studied the effects on pilot performance of both job-related stress and stress at home. A study based on a questionnaire administered to 19 U.S. Coast Guard helicopter pilots in 2000 found that, as stress at home increased, stress on the job also increased. “Pilots under stress at home felt tired and worried … at work,” said the U.S. Federal Aviation Administration (FAA) report on the study. “Pilots indicated that as the home stress experienced at work increased, self-perceptions of flying performance decreased, especially the sense of ‘not feeling ahead of the game.
Authors of the FAA report said that their findings were that the pilots surveyed identified their primary coping strategies as a stable spousal relationship, a stable home life and the ability to talk with an understanding partner. “The first warning signs of home-based psychological distress may be more evident in the daily work activities rather than in cockpit error,” the report said. “If support services and management recognized the early warning signs at work that were symptomatic of home-based stress, they could provide timely intervention before the occurrence of more serious flying performance decrements.”
An interesting point to note is that with continued efforts at stress management done, the stress curve can actually be increased to a higher level, resulting in higher and better performances.
In aviation, at all phases of flight, pilots are subjected to different amounts of stress; how they react when subjected to stress will ultimately make or break whether the outcome is a safe and successful flight.
The image below depicts the different amount of workload and hence stress the pilot faces during the different phases of flight. Stress/ Workload is highest during the critical junctures of flight which are taking off and landing.
|Picture embedded from Langley Flight School on 12 Sep 09|
Air Traffic Control (ATC) Stress
ATC is a highly demanding job with high stress levels due to the complexity involved balancing the controlling and deconflicting of numerous aircraft in an efficiently, expeditiously and safe manner whilst also catering for contingencies such as weather development and aircraft emergencies.
Due to this complexity, controllers require high cognitive capacities which include "spatial scanning, movement detection, image and pattern recognition, prioritizing, visual and verbal filtering, coding and decoding, inductive and deductive reasoning, short- and long-term memory, and mathematical and probabilistic reasoning". 
Aviation maintenance is a stressful task due to the fact that aircraft make money flying instead of being tended to in the hangar; hence there is enormous stress in finishing maintenance within a short timeframe and get the aircraft functional and flyable to avoid flight delays and cancellations. Whilst doing the job, there are also many things to be careful about in terms of using the correct tool, installing the correct parts whilst working in dark tight spaces. The stress can be self-imposed by increasing one's expectations of themselves and working harder than necessary to complete the job in the required time frame. The stress can also be from the manner or method that a manager uses to organise the employees. By not having the "people" skills to effectively communicate information or tasks to the engineers on the hanger floor, the manager risks stressing the engineers out by a lack of information. 
Flight-Crew Related Stress
For pilots and other crewmembers, even under ordinary conditions, the flight environment includes stressors such as noise, vibration, decreased barometric pressure, and accelerative forces. Fatigue and altered sleep-wake cycles also may be factors, especially for crewmembers on flights that span several times zones. Moreover, a 2000 study found that the captain’s personality type also influences the amount of stress on the flight deck.
During the study, 24 three-member flight crews performed line operations, including emergency operations, in a Boeing 737 simulator; afterward, they were tested for perceived stress. The crews that committed the fewest errors reported experiencing less stress than crews that committed more errors. The crews with the fewest errors typically were led by captains who were categorized in the report on the study as possessing the “right stuff” (for example, they were described as “active, warm, confident, competitive and preferring excellence and challenges”). Other captains were categorized as possessing either the “wrong stuff” (for example, they were described as arrogant, authoritarian, emotionally invulnerable, impatient, irritable, preferring excellence and challenging tasks, and having limited interpersonal warmth/sensitivity) or “no stuff” (for example, they were described as “unassertive [and] self-subordinating, [with] average interpersonal [skills], low self-confidence, low desire for challenging tasks and low desire for excellence”).
Sources of Stress
Causes of the stress are known as stressors.
These stressors add to the personnel's workload and make it uncomfortable for him in their work environment:
- High temperature build up in the cockpit/hangar increases perspiration and heart rate causing overheating of body.
- Low temperature build up causes the body to feel cold, weak and drowsy.
- Changes in air pressure due to turbulence exerts unusual g-forces on the body and makes it difficult to control the aircraft.
- Vibration transmitted to the body from the aircraft via the seat makes it difficult to read navigational charts and instruments.
- Noise levels in a typical cockpit are in the range 75-80 dB. Anything above this causes stress and makes it difficult to concentrate and forces the pilot to have to strain to hear ATC instructions. Noise levels in the hangars are also high due to hangars situated near aircraft taking off and landing, making it difficult for maintenance personnel to focus and concentrate.
- Poor Lightings at their work area make it difficult to read technical data and manuals whilst working on the aircraft and the use of torchlights are also inadequate, increasing the propensity to miss something important.
- Confined spaces also render maintenance personnel difficult to perform their tasks as their bodies are sometimes contorted in unusual positions.
- Poor visibility due to heavy fog and traveling in instrument meteorological conditions
- Work related stressors prior to the mission can increase arousal due to apprehension but too much can cause over-anxiousness and failure to perform up to speed. ie in ATC, envisioning handling multiple aircraft and making sure all are deconflicted and safe in the most expeditious manner.
- Financial problems such as impending bankruptcy, recession, loans and mortgages to pay.
- Marital problems due to divorce or strained relationships due to persistent quarreling.
- Interpersonal problems with superiors and colleagues due to miscommunication or perceived competition and backstabbing.
- Flying when unwell resulting in the body using more energy fighting the illness and hence less energy to perform vital tasks.
- Not having proper meals also result in not having enough energy and induces symptoms like headache and shaking.
- Lack of sleep; Fatigued, the pilot is unable to maintain performance standards for long periods as he struggling to stay awake. due long working hours
- Conflicting Shift Schedules affect the body's circadian cycle and lead to a degradation of performance.
- Working long hours without any break especially at busy airports when handling multiple aircraft departing and arriving on intersecting and parallel runways.
However, it is to be noted that a particular situation can bring about different degrees of difficulty for different people. The situation can be a stressor for one person and "normal" for another. Also, the stressor can cause stress in the same person when he is in a different predicament ie stressors which he has usually kept in checked suddenly is overwhelming him now due to perhaps increasingly turmoil in the family.
People cope with stress in many ways. Specialists say that the first step in coping is to identify stressors and the symptoms that occur after exposure to those stressors. Other recommendations involve development or maintenance of a healthy lifestyle, with adequate rest and exercise, a healthy diet, limited consumption of alcoholic drinks and avoidance of tobacco products.
- Maintain good physical fitness
- Have regular meals
- Have sufficient sleep
- Sound time management
- Control the physical environment
- Sound preparation with regard to knowledge, skills and procedures
- Have confidence in your training and ability
- Have a well balanced social,family life so that financial, domestic worries are not a problem
- Share and discuss problems so as not to bottle them up
- Solve problems as soon as possible to prevent snowball effect
• Remove the stressor, or change your way of thinking about the stressor;
• Seek training in common stress-reduction techniques such as meditation, yoga, tai chi; and biofeedback-assisted relaxation. Some people also find relief in prayer;
• Perform progressive muscle-relaxation or deep-breathing exercises;
• Talk to someone else about the situation. Psychiatrists, psychologists and licensed clinical social workers all have training to help people cope with situations that trigger a stress response;
• Visit a massage therapist, use a hot tub, or take a bath or shower;
• Exercise or play sports;
• Go outdoors; or,
• Listen to music, read a book, write in a journal or write a list, engage in a hobby or other enjoyable activity.
Stress management is an important skill for aviation personnel to hone so that they adequately cope with stress and prevent it from overwhelming their ability to respond properly at work.
- Recognize the potential signs and symptoms of stress
- Be proactive in removing the cause of stress ie turbulence in extreme weather by terminating the mission, according more priority to the emergency aircraft first before controlling other aircraft
- Removing yourself from the stressful situation by knowing one's own capability ie give up aerobatics learning and try something else if it is too much to handle, calling out for help from colleagues if in a very complex ATC scenario
- Prioritize actions in the cockpit ie handling the emergency vs chatter on radio telephony with ATC
- Do not be over focused in finishing the mission regardless of the situation ie impending weather, impeding deadline in completing the maintenance task
- Be current with all existing procedures and familiar at the workplace 
- Rendering the correct supervision by providing feedback to management if the deadline is impossible to attain
Want to know more?
- This page offers more detailed information about stress in ATC.
- Stress in Aviation Maintenance
- This article provides a comprehensive case study on occupational stress in aviation maintenance amongst personnel in Hong Kong.
- Thermal Stress
- An AviationKnowledge page specifically on Thermal Stress including both heat strain, cold stress, immersion and some countermeasures.