Human failure events (HFEs) are the unit of analysis in human reliability analysis (HRA). HFEs are essentially human errors that have an adverse consequence on system safety. In HRAs in the nuclear ...power industry, HFEs are typically defined in the probabilistic safety assessment (PSA), staring with possible hardware failures and then identifying opportunities for human action or inaction to affect those failures. In other industries, the HFE may not be predefined in this manner. For example, in the case of some oil and gas applications, the overarching quantitative risk analysis (QRA) does not identify HFEs. As human factors experts perform HRAs, there is difficulty in characterizing human actions in such a way that they represent the right level of analysis suitable for inclusion in the PSA or QRA. This paper provides guidance to help analysts in such a situation. The paper presents seven steps to build suitable HFEs based on an initial human factors task analysis.
Perfecting modern design of technical objects highlights the long-known truth that the human is the most unreliable link in the human-technical object system. However, this is a superficial finding ...not taking into account the root cause of human error – non-ergonomic working conditions. The desire to improve this situation by increasingly including ergonomic requirements, such as in the design of equipment interfaces, brings significant results. Suitable reduction of fatigue of varying nature, in many cases leads to a reduction in the number of errors among equipment operators. The system model assumes the possibility of a verification of psychomotor status in the workplace directly on the job, not relying on the test results to resume work and only allowing the diagnosis of an undesirable condition. The model is based on, among others, Fitts’ Law. The testing software is a form of web application. Each user has an account on which the results are collected and form the basis for drawing conclusions about the state of fatigue. It is necessary therefore to assume that for dedicated positions there is no risk of distraction by the need for an additional device. Time spent on the task cannot be reduced by the tasks resulting from work. The paradigmatic example of the application of this method can be demonstrated in a study of urban transport vehicles before leaving the initial stop. A study of psychomotor skills can be used as an alternative to the fairly common in some countries testing of alcohol content in exhaled air. There are also breathalyzers integrated in such a way with control of the vehicle, that it is only after the verification of sobriety that one can start the vehicle. There are also no reasons that this check cannot warrant a short psychomotor test.
NASA (National Aeronautics and Space Administration) Johnson Space Center (JSC) Safety and Mission Assurance (S&MA) uses two human reliability analysis (HRA) methodologies. The first is a simplified ...method which is based on how much time is available to complete the action, with consideration included for environmental and personal factors that could influence the human's reliability. This method is expected to provide a conservative value or placeholder as a preliminary estimate. This preliminary estimate or screening value is used to determine which placeholder needs a more detailed assessment. The second methodology is used to develop a more detailed human reliability assessment on the performance of critical human actions. This assessment needs to consider more than the time available, this would include factors such as: the importance of the action, the context, environmental factors, potential human stresses, previous experience, training, physical design interfaces, available procedures/checklists and internal human stresses. The more detailed assessment is expected to be more realistic than that based primarily on time available. When performing an HRA on a system or process that has an operational history, we have information specific to the task based on this history and experience. In the case of a Probabilistic Risk Assessment (PRA) that is based on a new design and has no operational history, providing a "reasonable" assessment of potential crew actions becomes more challenging. To determine what is expected of future operational parameters, the experience from individuals who had relevant experience and were familiar with the system and process previously implemented by NASA was used to provide the "best" available data. Personnel from Flight Operations, Flight Directors, Launch Test Directors, Control Room Console Operators, and Astronauts were all interviewed to provide a comprehensive picture of previous NASA operations. Verification of the assumptions and expectations expressed in the assessments will be needed when the procedures, flight rules, and operational requirements are developed and then finalized.
Human reliability analysis (HRA) contributes to assessment and to reduction of the impact of human operators to the risk of technologies and processes. The objective of this paper is to integrate ...realistic deterministic safety analysis and probabilistic safety assessment to show how deterministic safety analysis impacts the HRA, which is integrated into the probabilistic safety assessment. The RELAP5/MOD3.3 computer code is used for realistic safety analysis. Parametric safety analysis studies give time parameters for human actions as an input for selected HRA. Calculated human error probabilities are inserted into probabilistic safety assessment and the results are obtained, where the focus goes to the most important risk contributors. The method and the results are shown on selected HRA method through two selected representative human actions. Results show that realistic safety analysis represents an important standpoint for assessment of human error probabilities within HRA.
An expert elicitation approach has been developed to estimate probabilities for unsafe human actions (UAs) based on error-forcing contexts (EFCs) identified through the ATHEANA (A Technique for Human ...Event Analysis) search process. The expert elicitation approach integrates the knowledge of informed analysts to quantify UAs and treat uncertainty (‘quantification-including-uncertainty’). The analysis focuses on (a) the probabilistic risk assessment (PRA) sequence EFCs for which the UAs are being assessed, (b) the knowledge and experience of analysts (who should include trainers, operations staff, and PRA/human reliability analysis experts), and (c) facilitated translation of information into probabilities useful for PRA purposes. Rather than simply asking the analysts their opinion about failure probabilities, the approach emphasizes asking the analysts what experience and information they have that is relevant to the probability of failure. The facilitator then leads the group in combining the different kinds of information into a consensus probability distribution. This paper describes the expert elicitation process, presents its technical basis, and discusses the controls that are exercised to use it appropriately. The paper also points out the strengths and weaknesses of the approach and how it can be improved. Specifically, it describes how generalized contextually anchored probabilities (GCAPs) can be developed to serve as reference points for estimates of the likelihood of UAs and their distributions.
Quantified risk and safety assessments are now required for safety cases for European air traffic management (ATM) services. Since ATM is highly human-dependent for its safety, this suggests a need ...for formal human reliability assessment (HRA), as carried out in other industries such as nuclear power. Since the fundamental aspect of HRA is human error data, in the form of human error probabilities (HEPs), it was decided to take a first step towards development of an ATM HRA approach by deriving some HEPs in an ATM context.
This paper reports a study, which collected HEPs via analysing the results of a real-time simulation involving air traffic controllers (ATCOs) and pilots, with a focus on communication errors. This study did indeed derive HEPs that were found to be concordant with other known communication human error data. This is a first step, and shows promise for HRA in ATM, since HEPs have been derived which could be used in safety assessments, although these HEPs are for only one (albeit critical) aspect of ATCOs’ tasks (communications). The paper discusses options and potential ways forward for the development of a full HRA capability in ATM.
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