The starting point in any Human Factors analysis, be it for accident analysis, system design or evaluation, involves describing existing or analogous systems via the application of data collection methods. Task analysis methods are used to describe tasks and systems and typically involve describing activity in terms of the goals and physical and cognitive task steps required. Although the aim of accident analysis is typically to identify the causal factors involved, often different elements of the causes or different components of the system are focused on specifically. In recent times the trend is to focus on failures across the entire sociotechnical system; however, different components or levels of the system are also commonly focused on, including individual operators and equipment. The Critical Decision Method is a cognitive task analysis method that uses semi-structured interview to gather information regarding the cognitive processes employed by human operators during critical incidents.