## 1 Introduction  
The recent remarkable development of Information and Communication Technology (ICT) has had a large effect on the maritime domain. Shipping companies have introduced a number of automated and communication systems in their commercial vessels to improve cost-effective operation as well as to reduce the crew's workload and stress. The movement has already come to an 'autonomous' and 'unmanned' level, which is defined as Maritime Autonomous Surface Ship (MASS) at International Maritime Organization (IMO). Finterries and Rolls-Royce (currently Kongsberg) conducted a demonstration project on the autonomous ship in 2018 [1]. Yara International plans to operate a totally unmanned commercial ship in Norway, although the plan has been suspended [2]. Nippon Foundation started a new demonstration project to promote unmanned commercial ships in 2020 to operate them in 2025 [3]. Since the autonomous level of MASS is wide, many parties and organisations categorise them in their ways, such as Lloyds Register [4], Maritime UK [5] and IMO [6]. Although they set the fully autonomous situation, which decides a ship's action independently without supervision by a human, this extreme situation will not happen shortly considering the safety and security. Most MASS system will keep operators as a back-up function onboard ships as well as at another centre on land [7]. The operator takes the final role to maintain safety in case of the failure of the MASS system [8]. In this sense, the Remote Control Centre (RCC) will play a key role in the MASS system. Remote Operator (RO) is the core of the RCC. Although the role of RO is different according to the autonomous stage of MASS, the main task is to monitor and supervise the MASS operation and make a final decision of her action. In some cases, RO should immediately take over the operation control from the onboard autonomy computer system to correct its failure. The safety of unmanned remote control ships highly depends on the qualification of RO [9]. In fact, RO's competence and training are one of the most important elements to avoid accidents pertinent to human errors. Acquiring the competence on the appropriate watch for navigation is especially inevitable. It can be probed considering that the main common factors in collisions are bad decision-making and poor lookout during the duty on a watch [10]. ROs face the risk of making human error since they make the wrong recognition of the situation [7]. A regulatory flame is important not only to improve MASS but also to secure safety. A wide range of issues has been raised in previous research and discussion. Since the definitions of ship or vessel' are different among conventions, [PERSON] [11] suggests that Convention's and Treaty's interpretation rules should be thought about whether MASS is qualified as a vessel. All maritime-related international regulations in the IMO, such as the International Regulations for Preventing Collisions at Sea 1972 (COLREG) and the International Convention for the Safety of Life at Sea (SOLAS), have supposed that the master and crew are onboard. [PERSON] et al. [12] highlight that the 'proper lookout' rule of COLREG should be amended to allow only the computer to have a vision alone. IMO also started Regulatory Scoping Exercise (RSE) to assess the potential gap in existing IMO conventions and codes and 'analyse and select the most appropriate way of addressing MASS operations [6]'. When it comes to RO, seaferers' requirements on competence for navigation are regulated in the International Convention on Standards of Training, Certification and Watchkeeping for Seafarers (STCW). However, the STCW Convention has regulatory problems to be applied to MASS and RO, just like the other regulatory instruments. Article 3 of the Convention states that it applies to'seafarers serving onboard seagoing ships'. There is currently no clear understanding in the STCW Convention about whether RO is regarded as a master or a crew onboard.