Fatigue is a subjective feeling of tiredness that has a gradual onset. Fatigue can have physical or mental causes.
Physical fatigue is the transient inability of a muscle to maintain optimal physical performance, and is made more severe by intense physical exercise.
Mental fatigue is a transient decrease in maximal cognitive performance resulting from prolonged periods of cognitive activity. It can manifest as somnolence, lethargy, or directed attention fatigue.
Fatigue can be alleviated by periods of rest.
It is important to note that people are not the best evaluators of their own alertness state. They are often sleepier than they report.
In IVAO, we usually face mental fatigue as we fly alone and make long ATC control periods without rest.
Fatigue is recognized as one of the major factors that can impair human performance and has been cited as a cause of accidents and incidents in the transport industry.
It can manifest as somnolence, lethargy, or directed attention fatigue. Decreased attention may also be described as a more or less decreased level of consciousness.
Mental fatigue is a temporary inability to maintain optimal cognitive performance. The onset of mental fatigue during any cognitive activity is gradual, and depends upon an individual's cognitive ability, and also upon other factors, such as sleep deprivation and overall health.
Fatigue usually results in impaired standards of operation with increased likeliness of error. The effects are:
From a pilot's perspective, fatigue may result in:
From an ATC perspective, fatigue may result in:
| Physical Manifestations | Mental Manifestations |
|---|---|
| General feeling of tiredness | Difficulties in memorizing information |
| Reduction in vigilance | Lack of concentration |
| Growing and irresistible need to sleep | Periods of inattention |
| Nodding off/inadvertent napping | Slow understanding |
| Lethargy | Tendency to forget information and actions |
| Slowed reaction time | Bad mood |
| - | Poor decisions |