ABSTRACT: This paper deals with the problem of high failure rate often experienced on ships that are equipped with a new integrated navigation system. These "infant mortality" failures of the navigation system can form a significant risk to the safety of the ship, as the history has shown. Some accidents caused by this type of failures are briefly discussed. The paper highlights some factors that promote this problem. One of the most important factors is the low degree of standardisation of the bridge systems. Another factor is the incompleteness of the self diagnostics of a new system. The role of the self diagnostics is crucial in coping with failures, because the redundancy of the navigation systems is typically based on manual activation of the back-up device or function. The necessary corrective action by the user can be delayed too much if the self diagnostics of the system is not able to detect the failure. Proper testing of the new system during the harbour trials and the sea trials as well as utilisation of efficient failure analyses techniques is important for reducing the safety risk caused by the infant mortality failures. In the end of the paper, some practical experiences of using FMECA and HAZOP analysis in the development of the integrated navigation system of a large cruise vessel are presented.

KEYWORDS: Marine Navigation, Integrated Navigation System (INS), Marine Accidents, Infant Mortality, Self Diagnostics, Hazard and Operability Analysis (HAZOP), Failure Mode, Effect and Criticality Analysis (FMECA), Failure Analysis

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