The volume of commercial flight is rapidly increasing globally, and more than 4 billion passengers were transported by commercial airlines in 2017. Globally, 20,000 cities have flight connections, which is twice as much as 1995 (The International Air Transport Association 2017). Due to the increased competition between airlines, the number of off duty days has been cut down and work stress has increased among commercial pilots. Mental health, fatigue, and sleep problems is an important issue related to flight safety, especially highlighted after the Germanwings crash in 2015 (O’Hagan, McGinley et al. 2018, Pasha and Stokes 2018).
Though commercial pilots are initially selected to be healthy, questionnaire surveys have found a high prevalence of different types of medical illnesses. A recent study among Norwegian commercial pilots found that musculoskeletal complaints (53%) and gastrointestinal problems (60%) were very common, while allergies, depression, and respiratory symptoms were less common (Omholt, Ihlebæk et al. 2016). A study among Swedish pilots found that 39.5% had eye symptoms, 39.9% nasal symptoms (rhinitis) and 19.8% reported non-specific airway hyperactivity (Fu, Lindgren et al. 2015, Fu, Lindgren et al. 2016). Incidence of doctors’ diagnosed asthma among commercial pilots was 2.4 cases per 1000 person·years, slightly higher than the asthma incidence in the general population (Fu, Lindgren et al. 2016).
Sleep disturbances are common, especially among pilots operating international flights across time zones (Gander 1986). The study among Norwegian commercial pilots found that 68% had sleep problems, and fatigue was very common (81%) (Omholt, Ihlebæk et al. 2016). Another study from Portugal found that the majority of commercial pilots reported fatigue, after long-haul (84.4%) as well as after short-haul (93%) flights (Reis, Mestre et al. 2016). Pilots traveling across different time zones have longer sleep after homeward-bound flights than before the outward-bound flights(Anne Eriksen and Åkerstedt 2006), and they can usually recover to the baseline level at the third recovery sleep(Lowden and Åkerstedt 1999). Risk factors for fatigue among pilots include long duty hours, circadian disruptions from an inter-continental flight, and multi-segment duty during a day (Federal Aviation Administration, Samel, Wegmann et al. 1997, Bourgeois-Bougrine, Carbon et al. 2003, Fu, Lindgren et al. 2015, Honn, Satterfield et al. 2016). The chronic health problems may influence flight safety, but only a few pilots admit that they have ever made mistake during a flight because of fatigue (Aljurf, Olaish et al. 2018).
Self-rated health (SRH), also called self-reported health or perceived health, is a widely used indicator of health (De Bruin 1996). SRH, measured by a single question, has been proved to be a reliable predictor of mortality (Taloyan, Leineweber et al. 2015) and the development of chronic diseases (Latham and Peek 2013). SRH in the general population is influenced by social differences between countries (Schütte, Chastang et al. 2013), social-economic status (Alvarez-Galvez, Rodero-Cosano et al. 2013) and occupational factors (Niedhammer, Chastang et al. 2008). We found no previous study on risk factors for SRH among commercial pilots.
The concept of sense of coherence (SOC) was raised by Antonovsky. A high SOC is a personality trait reflecting the health-promoting capability to cope with stress(Antonovsky 1979, Antonovsky 1987). SOC is constructed with comprehensibility, manageability, and meaningfulness, and has been demonstrated to predict various aspects of health (Flensborg-Madsen, Ventegodt et al. 2005). The SOC scale has been used in occupational studies (Lundberg and Peck 1995, Schumann, Hapke et al. 2003, Ohta, Higuchi et al. 2015, Grodal, Innstrand et al. 2018) but we found no previous study on SOC among commercial pilots.
The psychosocial work environment can influence health and is usually studied by using the demands-control-support model (Del Pozo-Antunez, Ariza-Montes et al. 2018, Lecca, Campagna et al. 2018). The work condition with high demands, low control, and low social support is the most harmful (Johnson 1986, Johnson and Hall 1988). Among commercial pilots, low social support has been reported to be associated with sleep problems (Runeson, Lindgren et al. 2011). Recovery is an essential psychological process for detachment from work, and preparation for new work challenges. Recovery from work can be affected by psychological demands at work, sleep quality, leisure style (Zijlstra and Sonnentag 2006), and vacation (Bloom, Kompier et al. 2009, de Bloom, Geurts et al. 2010, de Bloom, Geurts et al. 2013). We found few studies on associations between psychosocial work conditions among commercial pilots and health (Lindgren, Andersson et al. 2002, Runeson, Lindgren et al. 2011), and no previous study on recovery from work in this occupational group.
When investigating health risks among pilots it is important to have a holistic perspective, including occupational as well as non-occupational risk factors. The aim is to study associations between occupational and non-occupational factors and SRH, recovery from work, fatigue and insomnia among commercial pilots. Our hypothesis in this study is that these four health variables can be influenced by work conditions (type of aircraft, type of flights, the psychosocial work environment) as well as SOC and socio-economic and life-style factors.