A very large number of accidents arise from ''human error''. But what does that phrase mean, and how may such errors and accidents be reduced? Human factors and ergonomics are synonyms for the discipline which takes an approach to the design of human-machine systems centered on the human participants. It is concerned not just with the size and shape of displays and controls, but also with human decision making, social interaction, and organizational problems. Since all of these interact, the design of a safe and efficient system in which humans play a major role involves far more than hardware engineering, and the application of human factors and ergonomics should not be left as an ''add on'', but integrated with other features of design from an early stage.