Pilot Fatigue Survey: Exploring Fatigue Factors in Air Medical Operations

Pilot fatigue in air medical operations

Gregory et al. explored fatigue factors in air medical operations in the USA in 20103. This article provides a meta-analysis of the original results.

Sleep inertia upon waking has the potential to impact flight safety. Rather than staying awake to avoid sleep inertia, 92% of respondents (n=639) said they preferred to sleep during night shifts and overcome sleep inertia if necessary.

Respondents were then asked how many hours sleep did they average on a typical night shift, and the maximum amount of sleep they obtained when not required to fly on a night shift. Table 1 highlights the percentage of pilots and the amounts of sleep these pilots claimed to get, both during a typical night shift (n=607) and during a no-fly night shift (n=582).

Table 1: Sleep attained during a night shift
Hours of sleep Average/typical night6 Confidence Interval7 maximum/no-fly night6 Confidence Interval7
<1 4% 1.5 1% 0.7
1-2 7% 1.9 1% 0.7
2-4 38% 3.6 10% 2.3
4-6 48% 3.5 37% 3.6
>6 5% 1.6 50% 3.8

The mean sleep pilots achieved on a typical night was 3.9 hours. However, 50% of pilots managed to get at least 6 hours sleep on a no-fly night. One question that was not asked in this research though, was how often a no-fly night occurred. 53% of respondents said they typically worked 3-4 consecutive night shifts (n=637), and another 37% worked up to 7 consecutive night shifts.

After an interrupted or reduced night's sleep the body builds up a sleep debit (Robson, 2008)4 that can only be recuperated by sleeping. According to Robson, the body's circadian rhythm prefers one period of longer sleep rather than several shorter periods to allow a balanced sleep of both deep and REM sleep5. Although respondents reported being able to get some sleep during the day after a night shift, this sleep is not as beneficial and revitalising as would be a longer sleep aligned with the body's circadian rhythm. Therefore, after each successive night of interrupted or reduced sleep, fatigue8 may accumulate.

The research found 84% of pilots reported that fatigue had affected their flight performance during an air medical operation (n=566). Table 2 provides a univariate analysis and summarises the phase of flight that respondents felt they were most affected by fatigue. Overall the most affected phase was whilst airborne (takeoff, enroute, descent and approach/landing). The second most common phase was during the preflight planning and walk-around phase. The least affected phase was during the engine start up, taxi and shutdown phases.

Table 2: Phase of flight most affected by fatigue
Phase Responses Confidence Interval7 Interpretation
Airborne 60% 3.7 most affected
Preflight planning and walk-around 25% 3.3
Engine start, taxi and shutdown 15% 2.7 least affected

Those who reported that fatigue had affected flight performance went on to report the symptoms they felt. Table 3 ranks the three most commonly reported symptoms. Note more than one symptom was allowed to be selected.

Table 3: Ways fatigue affected flight performance
Rank Symptom Responses Confidence Interval7
1 Degraded alertness 81% 3.0
2 Degraded performance 55% 3.8
3 Hard to concentrate 21% 3.1

Strategies for Combating Fatigue

Although the research Gregory et al.3 conducted did not specifically encompass ways to combat fatigue, an open-ended question asked respondents to list any suggestions or ideas from personal experience or known remedies. Table 4 highlights the most common suggestions to combat fatigue (n=434). Because this was an open ended question, it is assumed more than one response was allowed.

Table 4: Strategies suggested to combat fatigue
Strategy Number of times suggested % of Total Sample
Napping 182 26%
Exercise/activity 52 7%
Food 35 5%
Caffeine 26 4%

Table 4 shows that many suggestions were received for fatigue combating strategies. However, it is possible more respondents may have agreed they used these strategies or knew of them if a closed-ended question such as a 'tick all that apply' had been used. This may have yielded much higher results than that shown in the column '% of Total Sample'.


Research approach

  • Exploratory research into pilot fatigue factors in air medical operations.


  • A convenient sample of 697 air medical pilots participated in the research. This represents approximately 17% of all air medical pilots in the USA.
  • The sample comprised the following demographics: helicopter pilots (n=586), aeroplane pilots (n=45), flew both aeroplane and helicopter pilots (n=6); operated as single pilot (n=624), operated as two-pilot crew (n=13); line pilots (n=461), base managers (n=152), chief pilot or director of operations (n=3).


  • An online questionnaire containing 33 questions.
  • A mixture of questions including mainly closed-ended questions using multi-choice and Likert scaling. Two opened ended questions allowed respondents to provide further information.
  • The questionnaire was placed online at SurveyMonkey.com.


  • An invitation to participate in the research was made through the National EMS Pilot Association (NEMSPA) in the USA and via an email campaign.
  • Participants were provided with a link to the online survey, for completion.
  • All responses were anonymous.

Data analysis

  • The original article only provided frequencies and percentages. However, this meta-analysis provides further descriptive statistics, namely central tendency and confidence intervals.

Generalization potential

Given the exploratory approach of the research and its convenience, the results from this study may not have enough scope for generalization. They could be indicative of similar attitudes in the following 'populations' (in order of decreasing generalization power):

  • Air medical pilots with characteristics similar to this sample, namely USA pilots, flying helicopters, in single-pilot operations.
  • Air medical pilots of similar characteristics but working in other countries than the USA.
  • Air medical pilots with other characteristics such as flying aeroplanes, two-pilot operations.
  • Other commercial pilots flying night shifts or trans-meridian flights.
  • By gender.9

1. CALDWELL John A & Lynn CALDWELL (2003). Fatigue in aviation: A guide to staying awake at the stick. Aldershot, UK: Ashgate.
2. COSBY Paul C (2009). Methods in behavioral research. New York, USA: McGraw Hill.
3. GREGORY Kevin B, William WINN, Kent JOHNSON & Mark R ROSEKIND (2010). Pilot fatigue survey: Exploring fatigue factors in air medical operations. Air Medical Journal (ISSN 1067-991X), 2010, volume 29, number 6, pages 309-319.
4. ROBSON David (2008). Human Being Pilot: Human Factors for Aviation Professionals. Victoria, AUS: Aviation Theory Centre Pty Ltd.
+++ Notes +++
5. Rapid eye movement sleep.
6. The original published results did not add up to 100%, possibly due to rounding. To preserve the integrity of the original results they are carried over to this article, also not totalling 100%.
7. Confidence interval based on an estimated population of 4,000 air medical pilots in the USA and a 95% confidence level. Population calculated from estimate given in Gregory et al. (2010)3.
8. Fatigue can be defined as: The state of tiredness that is associated with long hours of work, prolonged periods without sleep, or the requirement to work at times that are 'out of sync' with the body's biological or circadian rhythms (Caldwell and Caldwell, 2003).1
9. The questionnaire did not ask for the gender of the respondent, so it is unclear how many males and females were used in the sample. Although pilots are generally a male dominated population, it is possible a high proportion of females responded. Females may differ from the way males interpret questions asked in a questionnaire (Cozby, 2009)2, especially about feelings such as fatigue.

Want to know more?

Original article
The full text of original article of this research can be obtained here.
The impact of fatigue in air medical and other types of operations: A review of fatigue facts and potential countermeasures
An article by John CALDWELL (2001). Earlier research into the same topic.
Fatigue in Aviation
Another article by John CALDWELL's (2005). Provides an in-depth discussion on some of the factors relating to fatigue in aviation.
Effects of sleep deprivation on cognitive performance by United States Air Force pilots
An article by Nadia LOPEZ, Fred PREVIC, Joseph FISCHER, Richard HEITZ and Randall Engle (2012). Examines the effects of sleep deprivation on performance of a variety of cognitive tasks as well as simulated flight.

Contributors to this page


Rhys POSTLEWAIGHT (2013). School of Aviation, Massey University, New Zealand (rhysposrhyspos).

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