SUMMARY A field study ofwork and sleep patterns among commercial merchant marine personnel is reported. Data collected over a 10-30-d period from 141 subjects aboard eight ships included information concerning work-rest schedules, sleep timing, alertness on the job and critical fatigue. The data indicate that watchstanders on the 4-on, 8-off schedule show considerable disruption in their sleep. The average sleep duration for all mariners is 6.6 h; watchstanders obtain their sleep in fragmented periods that are frequently less than 5 h in duration. Analysis of critical fatigue shows an incidence of 1 --240/0 across personnel and measures. Of particular concern are the watchstanders on the 04.00-08.00 schedule, who sleep less than 4 h per 24-h period 22% of the time.Potential countermeasures, including changes in scheduling and staffing are proposed.

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The contribution of ineffective communications to marine casualties was studied. A standardized procedure was used to guide casualty investigations by Coast Guard investigators over a six-month period. Analyses of the resulting 589 casualty reports were conducted to characterize the extent and nature of communications problems in critical marine casualties. The results suggest that increased efforts to address these problems through improvements in operational procedures and training could reduce occurrences of such casualties. The study procedures were revised for future use in marine casualty investigations. INTRODUCTION Communications problems are a potential contributor to accidents in any transportation mode that requires coordination among operators onboard a vehicle, between vehicles, or between a vehicle and a traffic control center. Reviews of aircraft accidents have cited communications problems among flight crews (Berman, 1995) and between pilots and air traffic controllers (Prinzo & Britton, 1993). Similar communications problems have also been identified as a contributor in marine casualties (National Research Council, 1994; Le Blanc & Rucks, 1996). Past studies have estimated that communications problems contribute to between 15 and 40 percent of marine casualties (

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The goal of this project was to develop a structured process for evaluating the capability of simulators to support mariner performance assessment. In this approach, simulator evaluation objectives and criteria are based on performance-based mariner assessment requirements. The approach produces a simulator evaluation protocol that addresses four areas of simulator capability: (1) providing flexible exercise programming to the assessor; (2) replicating the characteristics of actual equipment; (3) simulating the operational conditions required to demonstrate the desired mariner performance; and (4) supporting thorough debriefing of the assessment candidate. A case study showed that our evaluation process was feasible. The process proved to be both sensitive and valuable in differentiating the capabilities of two simulators used to support mariner assessment objectives. This approach can be generalized to the evaluation of simulators of equipment used in other industries.