Human-system concurrent task analysis for maritime autonomous surface ship operation and safety

•Autonomous ships will rely on system-human interaction in the near future.•The human-system interaction in autonomy (H-SIA) method is proposed.•H-SIA consists of an event sequence diagram and a concurrent task analysis (CoTA).•CoTA allows to identify dependent tasks and failure propagation between sub-systems.•H-SIA method analyses the system as whole, rather than each component separately. Maritime Autonomous Surface Ships (MASS) are the subject of a diversity of projects and some are in testing phase. MASS will probably include operators working in a shore control center (SCC), whose responsibilities may vary from supervision to remote control, according to Level of Autonomy (LoA) of the voyage. Moreover, MASS may operate with a dynamic LoA. The strong reliance on Human-Autonomous System collaboration and the dynamic LoA should be comprised on the analysis of MASS to ensure its safety; and are shortcomings of current methods. This paper presents the Human-System Interaction in Autonomy (H-SIA) method for MASS collision scenarios, and illustrates its application through a case study. H-SIA consists of an Event Sequence Diagram (ESD) and a concurrent task analysis (CoTA). The ESD models the scenario in a high level and consists of events related to all system's agents. The CoTA is a novel method to analyse complex systems. It comprises of Task Analysis of each agent, which are preformed concurrently, and uses specific rules for re-description. The H-SIA method analyses the system as whole, rather than focus on each component separately, allowing identification of dependent tasks between agents and visualization of propagation of failure between the agents’ tasks.