## 3 Case Study (Levels and Options of Factors (Step 1 in Figure 3))
### Levels and Options of Candidate Factors That May Affect the MWL of Operators (Step 1 in Figure 3)  
This case study sets the levels and options of factors in Table 1. There are many factors (variables); therefore, some of them had only one fixed option, to decrease the number of scenarios that interviewees should answer. At first, the ship type and size were set as a general type of vessel of 3000 gross tonnages (GT). This is because the highest rank in the competencies for seafarers that International Convention on Standards of Training, Certification and Watchkeeping of seafarers (STCW Convention) requires is a master (captain) and a chief mate of a ship of \"3000 gross tonnages (GT) and more\" (Regulation II/2). The goal to be achieved by operators was to navigate safely to the next port without a long delay. The study set only one option of operator's experience (deck officer), considering the number of interviewees. Operators were assumed to have no experience of navigating MASS because all interviewees had not yet experienced it. Finally, it was assumed that operators at the RCC could acquire the same information displayed on the bridge equipment (e.g., ECDIS and Radar/ARPA) without any delay. The next sections explain the detail of other factors.  
\begin{table}
\begin{tabular}{c c} \hline
**Factor** & **Option/Level** \\ \hline Ship size & Approximately 3000 gross tonnages (GT) \\ \hline Ship type & General type of ship (ocean-going ship) \\ \hline Goal of operators & Navigate safely to the next port without a long delay \\ \hline Weather & Clear, Rain, Heavy rain, and Fog (Section 3.2.1) \\ \hline Navigation area & Open sea, Coastal water, and Channel (Section 3.2.1) \\ \hline Traffic density & One vessel every four hours, Two vessels every one hour, and Five vessels every one hour. These vessels approached own ship at the same time (Section 3.2.1) \\ \hline Visibility & Visibility of 1 mile, 3 miles and 7 miles ahead from own ship \\  & (Section 3.2.1) \\ \hline Experience of operators & Deck officer \\ \hline
**\textlessAdditional factors for MASS\textgreater{}** & No autonomy, Navigation support system, Autonomous navigation \\ \hline Level of Autonomy (LoA) & system with monitoring and Autonomous navigation system without monitoring (Section 3.3.1) \\ \hline Level of Remote Control (LoRC) & No remote control, Support of navigation, and Navigation (Section 3.3.1) \\ \hline Manning Option (MO) & Combination of responsible officer and support officer between the bridge of a ship and remote-control centre (RCC) (Section 3.3.2) \\ \hline Level of Data Transmission to RCC (LoDT) (visibility on screen and sound at RCC) & Static image (one picture/10 s), rough video and clear video (Section 3.3.3) \\ \hline Level of Data Transmission to RCC (LoDT) (data of navigation equipment (e.g., ARPA/Radar and ECDIS)) & Same between the bridge and RCC (i.e., operators can acquire the same data without delay and trouble) \\ \hline Experience of MASS navigation (EoM) & No experience \\ \hline \end{tabular}
\end{table}
Table 1: Outline of factors that may affect MWL of operators in this study.