In this paper, the operability of the GMDSS is studied to identify those aspects that are hindering its successful use. Particular emphasis is placed upon the operator-equipment interface within the working environment of the ship's bridge. The results of a relevant survey, based on the opinion of recently G.O. certified navigation officers, indicate that – despite the automation in GMDSS and the resulting reduction of the human factor – there is a definite need to improve the knowledge-based proficiency of the operator. The current design of the system, and the increasing workload on the ship's bridge, constitute the main drawbacks to operability and dictate the requirement for improved knowledge and hence improved certification and refresher training for operators.