Fatigue in ATC

Fatigue in ATC

27TH ANNUAL CONFERENCE, Rio De Janeiro, Brazil, 26-29 April 1988

WP No. L004

Fatigue in ATC


This paper is intended to examine the condition of fatigue in ATC, to identify the causes of this condition and to suggest ways of delaying or diminishing its effect on the individual ATCO.

Fatigue as been defined as “a condition of cells or organs, in which, through over-activity, the power or capacity to respond to stimuli is diminished or lost”. An alternative definition is “a progressive decline in one’s ability to carry out an accepted task which may become apparent through deterioration in the quality of work, in accuracy or slowing of performance”. It must also be accepted that normal fatigue is a natural result of effort experienced by us all, every day.

There are at least four different types of fatigue:

  1. Muscular Fatigue: such as exhaustion after strenuous exercise, or straining in an uncomfortable posture;
  2. Mental Fatigue: usually induced by prolonged mental effort;
  3. Psychological Fatigue: brought on by excessive stress and emotion;
  4. Diurnal Disrhythmia: fatigue induced by disruption of the body’s natural rhythmic cycles.


Muscular fatigue:

Muscular fatigue can be the result of poor posture due to poor seating. Similarly, eye-muscle strain or neck muscle pains could be consequences of poor ergonomics or inappropriately designed operating positions.

Mental fatigue:

Normal mental fatigue is a temporary condition, reversed by adequate rest or sleep. When the recovery period is insufficient, the mentally-fatigued person is slow both to perceive problems and to solve them. Examples of mental fatigue are seen in attempts to take short cuts by omitting some required actions in order to simplify a task or rushing a job in a vain attempt to keep up with the required rate. It is well known, however, that high levels of mental arousal and familiarity with a task can counteract this type of fatigue, while at the same time often, increasing the consequent recovery required.

Psychological fatigue:

Mild degrees of stress should improve performance, but when stress levels exceed the optimum, performance deteriorates and recovery may be incomplete until a stress-inducing agent is removed. The stress-inducing agents can arise from various sources simultaneously and can produce different responses depending upon the psychological mode of the individual at the time. Recent academic studies show that if a person is in the ‘hedonic’ mode, he or she will experience exhilaration from a challenge. If, on the other hand, the individual is in the ‘agonic’ mode, anxiety may be produced by the same challenge. It is important, to note that any individual can be ‘switched’ from the ‘hedonic’ mode in which ‘normal’ competent people usually operate, to the self-defensive ‘agonic’ mode, in which performance is adversely affected.

Those switch stress-inducing agents encountered in ATC, which all induce a lack of confidence for the individual controller include:

  1. Inadequate training;
  2. Inadequate or unreliable equipment;
  3. Excessive work-load.

Other agents encountered in ATC include:

  1. Poor working environment;
  2. Insufficient control over ambient temperature, atmosphere, atmosphere, light, noise;
  3. Inadequate meal and fati gue breaks;
  4. Sleep deprivation.

Finally there are externally induced stresses which affect individual controllers from time to time, for example:

  1. Adverse family circumstances;
  2. Financial worries.

These agents can, in combination together, lead to a more rapid onset of fatigue then would normally be expected. Over a long period of exposure, they can result in heart disease, hypertension, peptic ulcers etc., or even psychiatric disorders such as neurosis.

Diurnal Disrhythmia:

Activity rhythms of shift duties may adjust rapidly, whereas sleep deprivation and appetite may require longer. The combination of high temperature and low humidity often found in air- conditioned operations rooms induce early fatigue, especially in the presence of tobacco smoke.


There are four principal types of fatigue encountered in ATCOs. In summary the effects of fatigue are:

  1. Reduction in level of skills;
  2. Increase in reaction time;
  3. Balanced judgement is weakened;
  4. Complex decision-making impaired.

Stress inducing agents are endemic in ATC and while they are limited to within acceptable levels and the individual controller is in the hedonic psychological mode, a welcome sense of job- satisfaction is engendered. However, even the same levels will induce anxiety when the same individual controller is in the agonic psychological mode. Higher-than-optimum levels of stress- inducing agents will exacerbate the situation of the agonic, and will lead initially to premature onset of fatigue in the hedonic, resulting ultimately in a switching ‘of the psychological mode to the agonic’ if not reduced in time.


MA’s should draw the attention of their members to the causes of fatigue in ATC so that they can identify those to which they are most exposed.

MA’s should advise their members to seek the possible reduction of these causes through their administrations or other agencies, in order to optimise the performance of their work.

MA’s should advise their members to seek professional psychological advice when they believe that they are subject to excessive stress-inducing agents.

Last Update: September 20, 2020  

December 2, 2019   434   Jean-Francois Lepage    1988    

Comments are closed.

  • Search Knowledgebase