A Comparison of 8-Hour vs. 12-Hour Shifts on Performance, Health and Safety in a USAF Aircraft Maintenance Squadron

This study examined the effects of converting a large USAF aircraft maintenance squadron from an 8- hour shift system to a 12-hour shift system. In 1996, the squadron converted its 24-hour operations from three 8-hour work shifts, to two 12-hour work shifts with compressed work weeks. The squadron maintained 12-hour shifts for 19 consecutive months. A comparison was made of organizational performance, worker health and safety measures before, during and after 12-hour shift implementation. Findings indicated that changing from 8- to 12-hour shifts resulted in a slight increase in aircraft Mission Capability rates. However, this benefit appears to have come at the expense of worker health, as evidenced by a ten-fold increase in worker sick-call visits to the base hospital. Additionally, the squadron expended a higher proportion of direct labor hours in support of the flying schedule. There were no significant differences in any other aircraft reliability, maintenance repair or deferred maintenance indicators. On- and off-duty accident rates were also examined. There were no significant differences noted between mean 8- and 12-hour shift accident rates. The decision to implement 12-hour shifts is one that must be made with careful consideration of the costs and benefits identified in this study.Air Force Inst of Tech Wright-Patterson AFB OH is the author of 'A Comparison of 8-Hour vs. 12-Hour Shifts on Performance, Health and Safety in a USAF Aircraft Maintenance Squadron' with ISBN 9781423557623 and ISBN 142355762X.