Cognitive Systems Engineering is a part of the systems engineering tradition that works with human-technology systems or so-called sociotechnical systems. Its main aim is to describe, analyse and explain how humans cope with complexity, how different adaptive components (humans and technological) come together to create socio-technical systems, how these socio-technical systems act, and ultimately, how socio-technical systems succeed and fail. Human factors are a multi-disciplinary research field which investigates the psychological, social, organisational and systemic characteristics of work systems and its human operators. Major research challenges in Human Factors are to investigate how human operators adapt and manage critically escalating work situations, e.g. how socio-technical systems succeed in maintaining safety and efficiency despite being exposed to adverse high-risk factors. Other important aspects are how human operators adapt to new technology/interfaces and how this adaptation affects the work system's ability to perform its intended work and reach its goals. Decision support systems for complex maritime operations. There is a steady increase in the complexity of maritime operations. Technical interfaces have more functions, new sensors make more information available, operators involved in operations are often geographically distributed and multiple processes operate simultaneously. Operations take place in harsh environments and the margins between success or failure can be small. Even though state-of-the art technology opens up new possibilities to present information there is a limit to how much information a Human Operator can make use of. More and more information or functions does not necessarily entail good Situation Awareness or good practice. The challenge that needs to be met in the design of decision support systems of the future is what information is actually needed, how to integrate this information in interface representations that are simple to understand and still richly informative for navigators or captains, and, how to integrate multiple sets of information into one integrated and coherent representation. The goal is to both support the human operator's intentions and goal-directed behaviours while making systems that are simple, reliable and adaptable. The paradox this goal invokes is that simpler systems must be made through more complex technological design, thus shifting complexity from the technical interfaces and its representations into the design process. User-centred design processes. Being in control is about having the ability to reach future goal-states. Thus, supporting human behaviour through the design of work tasks, technical systems or information flows is about enabling the operators to control the system in ways that fulfil the system's overarching goals. To create systems that support users it is important to understand 1) the user's intentions, 2) what information the operator uses, 3) what actions the must be done, and 4) how actions are performed. These four aspects cannot be unambiguously communicated by technical specifications because of the interpretative variability in design specifications. Work performed by expert human operators will always have elements of tacit knowledge which cannot be easily communicated to non-experts. The integration of the operator's knowledge into design processes is done through user-centred design which involves the end users during the planning, prototyping and testing of technical and work systems. This allows for a user-centred design process which focuses on the user and the system's goals rather than on technical specifications in combination with user-centred design. Modelling properties of complex sociotechnical work organisations. Complex maritime operations involve a multitude of human and technical operators who coordinate their work in order to reach a set of goals. Growing complexity makes the prediction of the system's behaviour more difficult to the point where it is impossible to predict the outcome of the system's work processes. Maritime operations involve a complex interplay between technology, humans, organisations and societal laws and regulations, components of different types and on different levels (e.g. individual, technical, organisational, societal), thus entailing a number of new and unexpected interactions and failure modes. Because ordinary componential conceptual or statistical modelling does not allow for accurate prediction there is a need for a set of systemic models that help differencing between those sociotechnical systems that succeed and those who fail.