Describe in detail the following human factors models: Reason’s Model (the Swiss Cheese Model) and the SHEL Model.

Question

Describe in detail a specific case or example in aviation where each of the models can be accurately applied.

Answer 1

Discussion should go toward Reason’s Model describing various organizational “barriers” in place designed to prevent errors from occurring. Among these barriers are decisions made by various levels of management, engineering controls (aircraft configuration, tools and equipment, etc.), system controls (training, procedures, oversight of leadership, etc.), and human behaviors. Reason’s Model likens organizational system defenses or “barriers” to a series of randomly holed Swiss cheese slices arranged vertically and parallel to each other with gaps between pieces. The holes in each slice represent weaknesses in the individual barriers of the system. System failures occur when an individual error or series of errors, hazard, poor decision, human action, or other event passes through the weaknesses in each of the barriers, leading to an accident or other undesired occurrence. Reason’s Model demonstrates that most aviation accidents and incidents can be traced to one or more levels of failure, including organizational influences, management practices, unsafe or inadequate supervision, preexisting system conditions, and the actual unsafe acts or behaviors committed by individuals or groups. When the “holes in the Swiss cheese” line up with each other, an accident may occur. SHEL stands for Software, Hardware, Environment, and Liveware. In the SHEL Model, Software represents the training, policies, rules, procedures, operating manuals of an organization. Hardware represents the tools, equipment, machines, and components used by people. Environment represents the location or system in which individuals are performing tasks. Liveware represents all the humans within the system. The primary point made by the SHEL Model is that humans are at the center of a complex aviation system designed to ensure a safe, efficient operation and mission. A closely related formulation is as follows: Given that people are at the center of the system , humans have the ability to impact and be impacted by each of the other components by virtue of interactions with them.

Open-ended answer that can be applied to a large number of specific cases.