Description & Background
This article is based exclusively on a study carried out by EUROCONTROL which led to a summary document on this subject being published in 2006 - see the references in Further Reading at the end of the article.
The purpose of the study was to identify best practices that can help define common solutions for managing shiftwork in European Air Traffic Management (ATM). The first part of the study contains a literature review about the impacts of shiftwork, its consequences for health, safety, productivity and efficiency, as well as its social implications. The second part “Shiftwork Practices Study - ATM and Related Industries” isolates common findings and presents solutions that could facilitate the planning and management of flexible working practices to improve safety and productivity in the safety critical shiftwork environment of ATM.
Shiftwork practices were collected for the study from various areas such as international ATM, medical, police and airline industries. There are an enormous amount of different shift systems. In the last few years, systems with short rotations have spread considerably. Alternate shift systems are more common in Europe than permanent systems.
Shiftwork in the ATM Context
Compared to other industries that make use of shiftwork, ATM has common features with some of them but also differs substantially in other aspects.
The most significant difference to most other industries is the substantial variation of workload during the day (inbound and outbound traffic peaks), during the week (weekday vs. weekend) and during the year (seasonal factors i.e. summer vs. winter traffic).
Within in the ATM context, the following aspects are especially important:
- ATM requires round the clock service in many units,
- safety is of critical importance relative to other businesses,
- complexity and dynamics are high relative to other businesses,
- workload varies due to daily, weekly and seasonal fluctuations of traffic,
- overload (stress) as well as underload (boredom) is an issue,
- ATCOs need to sustain a high level of performance.
Shiftwork and the Individual
There are reliable scientific findings that working at night causes a de-synchronisation of body functions. Human beings are day-active creatures, who are programmed to perform and be active during the day and to recover during the night. The problem arising from rotating shift systems, especially if night shifts are included, is the activation of the employees against their body clock. They have to work during the nights and to rest during the day.
The increased physical stress by working nights manifests itself in:
- a decrease of performance and
- an increase of tiredness.
The reduced efficiency leads to:
- an increased frequency of errors
- an extension of reaction times (decreased vigilance).
Night shiftworkers frequently mention troubles with body functions that are related to the circadian rhythm. The following are often expressed:
- sleep deficit / chronic fatigue
- gastrointestinal disorders
- reduced well-being.
A worker’s age is another crucial factor. The older employees are, the more difficult is the adaptation to night work. A phase model developed by EUROCONTROL describes shiftwork throughout a working career:
- Adaptation Phase (zero-five years): The shiftworker has to adapt to changes in sleeping and eating pattern, social and family life, and social strain.
- Sensitisation Phase (five-twenty years): Tolerance towards shiftwork develops.
- Accumulation Phase (twenty plus years): Risk factors, sleep quality and attitudes towards shiftwork accelerate the biological ageing process and have a strong influence on the health and the tolerance of the shiftwork.
- Manifestation Phase (twenty plus years): Some workers enter the manifestation phase before but also after retirement, which is characterised by an increase of disorders and diseases related to sustained shiftwork.
The following list summarises the problems faced by shiftworkers in working shift:
- Working in a rotating shift system (especially with night shifts) means working against the body clock (circadian rhythm) and leads to a de-synchronisation of the human body functions.
- Impairments of sleep, gastrointestinal and cardiovascular disorders can be the consequences. A so-called “healthy worker effect” is found: Only people fairly robust against the negative effects of shiftwork stay at the respective workplaces in the long run.
- Individual differences such as age, or the classification into morning and evening type, determine the effects of shiftwork as well.
- Apart from health impairments, shiftwork influences the social and family life.
The Relation of the Shiftwork to Performance and Safety
Present findings on night and shiftwork prove a higher risk of physical and mental impairments for employees working in atypical shift systems as compared with employees with regular working hours. The increased risk of impairments arises from the following factors:
- The de-synchronisation of working time combined with different working requirements
- The capability according to the physiological and social conditions.
The study established that:
- The risk increases from early to late shift and is highest during the night shift.
- The risk increases until the seventh successive shift.
- During day shift, a break is due, at the latest, after four hours. Tasks demanding high levels of vigilance should be followed by a break after two hours. The minimum duration of a break should be ten minutes plus five minutes for every hour worked.
- During night shift, the risk of fatigue is even more enhanced since the employee is working against the circadian rhythm. Special considerations might be taken into account for breaks that may allow napping and enough time to overcome the subsequent inertia.
- The design of night shifts generally should take into account the variability of real life settings compared to laboratory settings - this for example refers to experiments measuring reaction times (laboratory) which do not fully reflect the variability of work demands in the actual night work situation.
- The demands for designing rosters for night shift support the European Directive 93/104 which restricts the night shift to eight hours.
The research emphasises that a best shift system in ATM cannot be defined. The specific conditions of the work situation, the workload, its spatial and temporal distribution, the individual conditions such as age, attitude, and social support as well as the organisational frame play a vital role in the design of shift systems. However, taking into account the findings from existing research the following guidelines are provided for shiftwork design. For best practices recommendations on shift design derived from the literature review, see Figure 1 below.
Figure 1. Ten Recommendations on Shiftwork.
The literature review conducted by EUROCONTROL has demonstrated that, despite considerable knowledge on shift management, many questions remain open and need to be specified for the particular situation faced by Air Navigation Service Provider. The issues of cost-effective shift management and productivity were rarely investigated and, if so, they were secondary to the study of accident prevention and health promotion.
- ^ Some of the recommendations are contradictory and difficult or impossible to implemented at the same time. This is most obviously the case for recommendations Nos. 6 and 7. Within continuous productions or a 24-hour service company, recommendation No.7 contradicts with recommendation No.6.
- ^ A dedicated chapter of the literature review carried out by EUROCONTROL depicts aviation-specific issues and delineates exemplary European studies concerning shiftwork and atypical working hours in the field of aviation. The reports are based on research of the authors (Denmark, Germany) or on available publications from other countries. Shiftwork studies for countries outside Europe (USA and Australia) are outlined into separate annex. For detailed summaries of the studies see Managing Shiftwork in European ATM: Literature Review, Chapter 6, Research Examples