This study consisted of four main steps, including the identification of influencing factors, selection of the ports being investigated, estimation of the factors’ weights and evaluation of the ports’ safety. The first step is to identify the critical factors influencing port safety from a captain’s perspective. The safety factors were identified through the combination of literature reviews and in-depth interviews with domain experts. The in-depth interviews ensure that the factors which are important indicated by the relevant literature but not suitable to modeling the navigational safety in Korean ports, are eliminated. In order to identify and categorize the most relevant factors, a panel containing five navigationally experienced experts and a port authority was formed. The panel first selected five main factors from more than ten total factors (identified through the literature review) and then developed the sub-factors of each main one based on literature review and Korean port practices through a brainstorming process, as seen in Fig. 1. The main factors and sub-factors were selected based on the following three questions.