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