## 6 Discussion
The expert suggested that ROs could handle this difficult situation only when they have seagoing experience and get the navigational expertise described above. Young professionals lack the skill to 'grasp relevant information from their environment' under uncertain situations [18]. Experience of seagoing is essential to appropriately review the condition of the autonomous ship [49]. Considering these, 'experience' is the crucial item to supplement the lack of ship sense and failure of the required information. In this regard, more experience of seagoing service after being engaged in watchkeeping should be added. The second is the competence for fail-safe. Although the case study does not cover emergency situations such as fire, collision and grounding, sudden intermittent delay of visual data is likely to happen even if redundancy has been kept. In this case, visual sense will face unusual failure. Encountering ships might be close to the ship at the same time. According to an expert, even in this situation, RO should have the competence to appropriately specify the cause of the condition and predict the next event on the screen at RCC in bounded time without panic. Although professional crews can control a ship in the'strategic' way even under complicated situations based on the experience of seagoing service [19], they do not have competence for the fail-safe due to the lack of the experience of 'visual intermittent'. Therefore, the seagoing service's ample expertise is not sufficient for handling these situations, and another requirement on the fail-safe should be newly added to the regulation. Moreover, the training methods to get this competence are also important. Since it is difficult to make these situations in non-MASS ships, the simulation and virtual reality (VR) training will be one of them. The next is the fundamental and theoretical knowledge of a ship, including ship motion, bridge equipment, data communication and meteorology. The abilities that RO should hold are built on fundamental knowledge. For instance, the ship's motion changes depending on various natural elements such as speed and direction of a wind, ship condition such as ballast condition and a ship's character such as manoeuvring characteristics, including course changing and stopping ability and ship size. Being familiar with the fundamental nature and specification of bridge equipment is also essential since manoeuvre at RCC should highly rely on the human-machine interface with the limited visual sense. Moreover, basic knowledge of wireless data communication is necessary, bearing in mind that ships will seek a'more comprehensive communication system' [50]. Although officers engaged in watchkeeping currently learn most of this fundamental knowledge, RO's competence level should be more profound. The last is the bridge resource management (BRM), which is the regulatory requirements introduced in STCW2010 and includes 'teamwork and leadership' [51]. The necessity of this competence depends on the formation of bridge manning. An expert mentioned that this competence might be less critical if the RO were engaged in the watchkeeping of an unmanned ship alone at RCC. However, more profound knowledge is necessary for this study since RO and Look-out should navigate the ship as a team under restricted conditions. Moreover, the separation of the navigation crews between the bridge of a ship and RCC will make BRM much more difficult. The overlook of essential information for safety is caused by inappropriate manning [52], and BRM and leadership are indispensable competence to secure the operation of manning. Moreover, according to [PERSON] and [PERSON] [34], a new leadership style, such as a non-hierarchical type connecting man and machine, might be expected. Considering these, the competence of BRM and leadership will be more critical except for a few special cases. Although this study looks for the item that can be removed from the current requirements besides the additional requirements, the results are quite limited.