Perception of fatigue issues on different flight operations

Perception of fatigue issues on different flight operations

Fatigue level is associated with different types of flight operations. Yen, Chiung, Yang & Ho carried out research in 2009, to investigate the perceived physical and mental fatigue of various kinds of flight operations by pilots from Taiwanese airlines. This article provides a descriptive analysis based on the original results.

Illustration 1 shows that there are difference in level of fatigue perceived by the pilot before and after flight duty, with respect to 3 types of flight operations differentiated according to the length of flight time. Among the 3 groups, the oceanic crews perceived the highest fatigue level with greater mean difference of 0.77 and 0.64 than that of regional and domestic operations. The results (when attending to standard deviation) also suggest a more uniform distribution of increase in mental fatigue level than the corresponding distribution for physical fatigue level.

Illustration 1: Before flight and after flight differences in fatigue level (Mean Difference)
Oceanic (n=96) Regional (n=253) Domestic (n=191)
Measures Mean Std Dev Mean Std Dev Mean Std Dev
Physical Fatigue * 0.77 0.34 0.34 0.22 0.2 0.16
Mental Fatigue ** 0.64 0.15 0.21 0.09 0.15 0.08
*Based on 24-item physical fatigue questionnaires
** Based on 19-item mental fatigue questionnaires

Illustration 2 provides a comparison of fatigue level arising from different types of flight operations. As there is no statistically significant difference in the perceived fatigue level before flight between 3 groups, a comparison only made for fatigue level perceived after flight between 3 groups. Findings show that pilots operating oceanic flight operations have the greatest increase in overall fatigue (physical and mental fatigue), followed by regional and then domestic operations. Although there is significant difference between regional and domestic, p value at 0.05, it suggests the fatigue perceived is not as severe as compared to pilots operating oceanic flights.

Illustration 2: Comparison of overall fatigue level after flight
Comparison P value @ Level of significant Interpretation
Oceanic vs regional 0.01 Highly significant Great increase in fatigue
Oceanic vs domestic 0.01 Highly significant Great increase in fatigue
Regional vs domestic 0.05 Significant Increase in fatigue

Overall, majority of pilots perceived flight performance and flight safety is affected by fatigue. In illustration 3, the majority, 96% of pilots operating oceanic flight rated the influence as moderate, serious and extreme. The percentage fell to 89% for those operating regional flights and number decreased to 72% for those operating on domestic flights. Based on the results it addresses a concern among pilots about the influence of fatigue on flight performance and flight safety.

Illustration 3: Fatigue response from pilots Statistic
Not at all (1) Minor (2) Moderate (3) Serious (4) Extreme (5) Mean
Oceanic 0 6 56 100 30 3.8
Regional 2 67 149 207 81 3.6
Domestic 10 93 125 128 26 3.2

Study’s scope

The sample used pilots from 6 different airlines in Taiwan with 3 types of flight operations: oceanic flight, regional flight and domestic flight. Only 540 pilots who completed both questionnaires (before and after flight duty) were included in the analysis to compare fatigue level. The results confirm that the perceived fatigue level increases due to flight duty, regardless of different type of flight operations. This study also provides a good comparison of fatigue level associated with the 3 types of operations with pilots operating oceanic flights have the greatest increase in physical and mental fatigue.


Research approach

This was an exploratory research into the fatigue level perceived by pilots from operating different kinds of flight operations.


The research used sample of pilots from 6 different airlines in Taiwan - 1062 captains and 831 FOs of which 446 pilots (392 captains and 54 FOs) were not Taiwanese. Only 540 pilots returned the questionnaires. Majority of them are from China Airlines and EVA Air. Two of the six airlines (China Airlines and EVA Air) provide only international services, while the other four provide both regional and domestic services. All domestic flights in Taiwan are less than 1 hour hence are classified as short haul flight operations. International flights are divided into regional (2-6h) and oceanic (more than 6hr)


Yen, Chiung, Yang & Ho (2009) used rating system (from 0 standing for none to 4 for very high) to measure pilots’ perception of the fatigue level from operating different types of flight operations: Oceanic, regional and domestic. In this article, those items rated in the questionnaires have been categorized into the following:

• Physical fatigue (effects on the way pilot carry out task safely)
- Eye irritation, fixed stare, falling eyelidsd
- Backache, limb stretching, drowsiness and headache
- Impatience, aggressiveness, efforts to maintain wakefulness, depressive state

• Mental fatigue (effects on the mind to function properly)
- Difficulty in making decision, easily distracted
- Slips, lapse or minor errors, mistakes on calculation, redundancy of some actions
- Lack of anticipation, lack of coherence in reasoning

Data analysis

This analysis uses descriptive statistics, namely central tendency and dispersion from the original article to present the results in more quantifiable way of fatigue effect that pilots perceived.


Jin-Ru Yen, Chiung-Chi Hsu, Hsuan Yang & Hero Ho (2009). An investigation of fatigue issues on different flight operations. Journal of Air Transport Management 15, pages 236-240, 2009.


FunFun (2013). Massey University, New Zealand/ Singapore Campus.Fun FunFun Fun

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