The Human Factors Analysis and Classification System (HFACS) was developed as a categorization system of latent and active errors that served as causal factors that have been identified in aviation accidents. Its main purpose is to act as a FRAMEWORK for use in aviation accident investigations and as a tool for assessing accident trends. HFACS was developed base on James Reason’s model of latent and active failures . Generally referred to as the “Swiss cheese” model of human error, James Reason describes four levels of human failure, its active and latent errors involved and how these factors build-up towards a mishap (see post above for elaboration on Swiss Cheese Model). By strict definition, active errors described as errors that have an immediate effect whereas a latent error would be a decision of action that has no immediate effect but lays hidden in the system till all factors come together and culminate resulting in an accident.
HFACS was devised specifically to define the failures within the elements of production formulated by Reason. It was originally developed by the US Air Force as a means of investigating and analysing human error in military aviation accidents. HFACS was employed as an adjunct to their accident investigation and analysis procedures.
HFACS further subdivides preconditions of unsafe acts into substandard of practice and questionable conditions of the operators. Practices of substandard generally refer to poor decision making procedures at the flight deck. Such practices tend to point towards poor crew resource management which also includes communications outside the cockpit such as Air Traffic Control, ground personnel, cabin crew and engineers. Poor or unsuitable conditions of operators focus on adverse mental states such as circadian rhythm disruption, mental fatigue and complacency. Other conditions include physical and mental limitations that affect the sensory registry of a pilot to adequately perform his primary duties. Adverse physiological states also play a significant role in creating non conducive substandard conditions, which include baro-traumas, disorientation and visual/auditory illusions.
In aviation, it is often the case that latent failure at the flight deck can be traced to the supervisory authority. These substandard acts of supervision unknowingly become the large and highly significant hole of latent error in the slice of Reason’s cheese that facilitates the feasibility of an occurrence. Unsafe supervision is broken down into three sub-sects, inadequate supervision , planned inappropriate operations and failure to rectify the issues which basically looks at the destructive effects of being reactive rather than proactive
Commercial pressures particularly from high level management often conflict with practices and procedures of the operators. These organisational influences represent latent failures that represent imminent danger to aviation operations. The influences revolve around three main issues, operational processes, organisational climate and resource management
HFACS classifies unsafe acts by operators into the errors and violations involved. Errors refer to physical or mental activities of individuals that fail to achieve its intended outcome. By human nature, errors make up majority of cases studied in aviation. Due to the overwhelming role of errors, it has been further sub-class under the nature of the error; decision errors, perceptual errors and skill based errors
|(Image embedded from FAA on 11 January 2010)|
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