# A Study on Identification of Development Status of MASS Technologies and Directions of Improvement
## 5 Hazard Analysis for MASS
She also claimed that adding new features to traditional hazard analysis methods were not successful, because the underlying assumptions of traditional methods do not account for the actual hazards of modern complex systems. [PERSON] [64] argued that traditional safety efforts, including traditional hazard analysis methods, focused on unwanted or negative outcomes so that they do not apply to intractable systems. Intractable systems are defined as systems whose descriptions elaborate on many details, where the rate of change is high, comprehensibility is low, and the characteristics of processes are heterogeneous and possible irregular; autonomous ships can be classified as an intractable system. Therefore, a couple of new methods have been developed to analyze the hazards of modern, complex, and software-intensive socio-technical systems, and these new methods have been applied to hazard analysis for autonomous ships recently. STPA is a relative new hazard analysis technique based on the system-theoretic accident model and processes (STAMP). While the main focus of traditional accident casualty models is a chain of directly related failure events or component failures, STAMP explains that the accidents of modern complex systems can also occur by unsafe interactions among system components without any failure events. With this underlying principle, STPA is capable of analyzing the hazards of unsafe interactions (controls and feedbacks), as well as component failures (execution of control actions) [65]. STPA has been widely used in various industries and sectors such as aviation, aerospace, defense, nuclear power plants, oil and gas industries, automobiles, cybersecurity, and so on, and this method has been gaining interest and application in the maritime domain recently [66], especially for the hazard analysis of autonomous ships. For instance, [PERSON] et al. [67] applied STPA to develop and analyze a preliminary model of autonomous ships. [PERSON] et al. [68] presented a systematic hazard management process for the concept design of autonomous ships using STPA. [PERSON] et al. [60] applied STPA to  
Figure 3: Remaining incidents in the autonomous ship after implementing autonomous navigation systems [59]. compare hazards associated with different ship autonomy types, and [PERSON] et al. [69] investigated the uncertainties of autonomous ships using STPA. The efforts to improve the safety of autonomous ships using STPA are expected to grow further, based on the fact that STPA is a tailor-made hazard analysis method for analysis of modern complex systems and is already widely used for the analysis of many different complex and autonomous systems. The FRAM is also a relatively new method to model and analyze complex operations and activities in socio-technical systems, and this method is based on a new safety paradigm, resilience engineering [64]. Resilience means the ability that a system can recognize and adapt to handle unanticipated situations, and therefore, resilience engineering focuses on improving the ability of a system to succeed, while the traditional safety approaches aim to reduce the number of failures or adverse events [70]. The main goal of FRAM is to understand complex functions and activities of socio-technical systems in order to achieve more resilient systems [71], and FRAM has been widely adopted for both risk assessment and accident analysis of various industries and sectors, like aviation, nuclear power plants, oil refinery, railway security, and so on [72]. The potential of FRAM for the hazard analysis of autonomous ships has been discussed by several studies. [PERSON] et al. [73] emphasized that that FRAM (together with STPA) can contribute to the safe deployment of autonomous ships. [PERSON] et al. [74] concluded that FRAM and STPA can be optimal methods to analyze the hazards of complex and interconnected systems of autonomous ships, and [PERSON] et al. [75] argued that systemic safety models (like FRAM and STAMP) can be candidates for assessing safety in designing autonomous ships.