Human Factors

Human Factors have been widely cited as the primary factor in many aviation accidents. In order to understand how people respond to different circumstances, we must analyze past accidents, incidents, and any other occurrences through a human factors model in order to increase safety and efficiency in the future.

The human element is the most flexible, adaptable, and valuable part of the aviation system, but it is also the most vulnerable to influences which can adversely affect its performance. Errors attributed to humans in the system can be design induced, or stimulated by inadequate training, badly designed procedures, or the poor concept or layout of checklists or manuals. An understanding of predictable human capabilities and limitations, as well as the application of this understanding, are the primary concerns of Human Factors.

It is helpful to use a model to aid in the understanding of Human Factors. This allows a gradual approach to comprehension. One practical diagram to illustrate a conceptual model uses blocks to represent the different components of Human Factors. The model can be built up one block at a time, with a pictoral impression being given of the need for matching the components. The name of the SHEL Model is derived from the initial letters of its components: Software, Hardware, Environment, and Liveware.

The basis of the SHEL system is the premise that what people do in a work situation is determined not only by their capabilities and limitations, but also by the machines they work with, the rules and procedures governing their activities, and the total environment within which the activity takes place. The model states that Hardware, Software, and Liveware (human elements) are all system resources that interact together and with their Environment. Accidents are described as the symptomatic failure of one of the components in the model. In order for the SHEL system to be adopted, a change in the thought process is needed so that accidents will not be regarded as isolated events of a relatively arbitrary nature, due mostly to carelessness.