Shift Work Schedule

Introduction
Due to the need to provide non-stop continuous armed, intelligence, surveillance and reconnaissance (ISR) functions in conflict zone operations, the squadron operating the MQ-1B medium altitude, long endurance (MALE) UASs has to implement shift work for its UAS crews. However, it has been well documented that shift work often lead to human factor health concerns such as sleep loss, circadian disruption and subsequent fatigue, accompanied by degraded job performance and increased risk for human errors (Thompson, 2006). UAS pilots have been reported to work an average of 900 hours a year, compared to only 250 hours a year for manned fighter aircraft pilots (Hennigan, 2015). Therefore, there is a need to design good shift systems for UAS crews to minimize the adverse associated human factors effects such as fatigue, stress and other sleep disorders.
 
Existing shift work schedule and its issues
The UAS squadron’s existing shift work schedule is supported by 4 teams of UAS crews that work continuously for six days in a single shift followed by two days off as shown in Table 1 below. The shifts for each team follow a clockwise (forward) rotating cycle from day to swing and then to night shift. Unfortunately, extreme fatigue with complaints of inadequate sleep has been reported by the crew operating according to the schedule. The continuous 6 nights of work is detrimental to the well-being of crews. Sallinen and Kecklund (2010) reported that severe sleepiness in night shifts was due to the daytime oriented circadian rhythm of alertness that made sleeping or resting difficult and also hard to stay alert at night, and that 28% of night shift workers involuntarily dozed off and slept during 40 minutes of the shift. The rotation from day, evening and night shifts forces the crew to adjust their body functions to duty periods which can result in a progressive phase shift of circadian rhythms across the successive night shifts (Costa, 2003). In addition, working 6 or more consecutive shifts and more than 35 hours per week has been found to aggravate complaints of awakening and a higher need to recovery (Van de Ven et al., 2016). The current shift system requires the crew to work approximately 51 hours per week on 6 consecutive days on a single shift. Thus it is much longer than a typical U.S. worker work week of 34.4 hours (Snyder & Jones, 2015). However, Viitasalo et al. asserted that this 3-shifts forward rotating schedule is still better than backward rotating ones (as cited in Sallinen and Keckund, 2010, p. 130).

Table 1
Existing squadron shift schedule

Recommended shift work schedule and its benefits
Based on the report by Kundi (2010), there should not be more than three night shifts in a row for a good shift schedule. In another separate article by Burgess (2007), it is recommended that 3 day shifts, 3 evening shifts (swing), 3 night shifts, and 3 recuperating days off be implemented to have 24/7 coverage of duties. It was also asserted that 8-hour, clockwise rotating shifts are preferred. The recommended shift schedule, as shown in Table 2 below, features a 3-shift clockwise (forward) rotating shift system that provides coverage for daily 24/7 operations. Each team is only required to work in a single shift for consecutive 3 days in a clockwise (forward) rotating manner. Although the total number of working hours per week is about the same as the existing schedule, and every team has to work 9 consecutive days before getting a break, the new schedule allows the much needed rest of 3 days after every 3 consecutive night shifts.

Table 2
Recommended new shift schedule

   

Conclusion
It remains an important focus to continue to design effective shift systems for UAS crews that requires 24/7 operations to mitigate any negative human factor issues during work. The recommended new schedule provides the necessary operational coverage with the same number of crew and working hours. However, it provides the added benefit of allowing adequate crew rest after consecutive night shifts to reduce fatigue and prevent other problems from any disruption of human circadian rhythm. It is assumed during design that UAS crews are relatively young and the crew numbers are fixed. However, these are also valid considerations when designing shift work schedules for other organizations with a more dynamic workforce age and manning numbers.

References
Burgess, P. A. (2007). Optimal Shift Duration and Sequence: Recommended Approach for Short-Term Emergency Response Activations for Public Health and Emergency Management. American Journal of Public Health, 97(Suppl 1), S88–S92. http://doi.org/10.2105/AJPH.2005.078782

Costa, G. (2003). Shift work and occupational medicine: an overview. Occupational medicine, 53(2), 83-88.

Hennigan, W.J. (2015, November 9). Air Force struggles to add drone pilots and address fatigue and stress. Los Angeles Times. Retrieved from http://www.latimes.com/nation/la-na-drone-pilot-crisis-20151109-story.html

Kundi, M. (2003). Ergonomic criteria for the evaluation of shift schedules. Theoretical Issues in Ergonomics Science, 4(3), 302-318. doi:10.1080/14639220210158907

Sallinen, M., & Kecklund, G. (2010). Shift work, sleep, and sleepiness — differences between shift schedules and systems. Scandinavian Journal of Work, Environment & Health, 36(2), 121-133. doi:10.5271/sjweh.2900

Snyder, B., & Jones, S. (2015, November 11). Americans work hard, but people in these 15 countries work longer hours. Fortune. Retrieved from http://fortune.com/2015/11/11/chart-work-week-oecd/

Thompson, W. T., Lopez, N., Hickey, P., DaLuz, C., Caldwell, J. L., Tvaryanas, A. P., & HUMAN SYSTEMS WING (311TH) BROOKS AFB TX. (2006). Effects of shift work and sustained operations: Operator performance in remotely piloted aircraft (OP-REPAIR)

Van de Ven, Hardy A, Brouwer, S., Koolhaas, W., Goudswaard, A., de Looze, M. P., Kecklund, G.. . van der Klink, Jac J.L. (2016). Associations between shift schedule characteristics with sleep, need for recovery, health and performance measures for regular (semi-)continuous 3-shift systems. Applied Ergonomics, 56, 203-212. doi:10.1016/j.apergo.2016.04.004