Task analysis is a fundamental tool of human factors engineering. It entails analyzing how a task is accomplished, including a detailed description of both manual and mental activities, task and element durations, task frequency, task allocation, task complexity, environmental conditions, necessary clothing and equipment, and any other unique factors involved in or required for one or more people to perform a given task. Information from a task analysis can then be used for many purposes, such as personnel selection and training, tool or equipment design, procedure design (e.g., design of checklists, or decision support systems) and automation. Though distinct, task analysis is related to user analysis. Safety Critical Task Analysis Safety Critical Task Analysis (SCTA) focuses on how tasks that are critical to major accident risk are performed. SCTA is a crucial assessment designed to predict and understand the role that human error plays in major accidents. This is a type or workshop conducted to support Major Accident Hazard (MAH) industries, such as oil and gas, chemicals. Those activities or tasks that are identified as being safety critical (i.e. may result in significant impact to the environment or harm to people if completed incorrectly), are put through an SCTA which would break down the task into a step-by-step process and review where the most likely points of error are to occur. The aim of this is to identify where additional control measures can be introduced that would reduce the likelihood of human error in completing such an important task. The Energy Institute in the UK, has released a guidance document titled "Guidance on Human Factors Safety Critical Analysis" Applications The term "task" is often used interchangeably with activity or process. Task analysis often results in a hierarchical representation of what steps it takes to perform a task for which there is a goal and for which there is some lowest-level "action" or interaction among humans and/or machines: this is known as hierarchical task analysis. Tasks may be identified and defined at multiple levels of abstraction as required to support the purpose of the analysis. A critical task analysis, for example, is an analysis of human performance requirements which, if not accomplished in accordance with system requirements, will likely have adverse effects on cost, system reliability, efficiency, effectiveness, or safety. Task analysis is often performed by human factors and ergonomics professionals. Task analysis may be of manual tasks, such as bricklaying,