This chart demonstrates typical sources of error-prone interface design. The illustration is of a manually controlled boiler, namely in which the operator needs to control the temperature manually.
A sensor (thermometer) is used to provide input to the operator about the machine situation. This is the primary means for fault detection. The operator uses the input perceived from the indicator to decide when and how to activate the control (a power on-off switch)
This design is error-prone. The critical component is this design is the operator, who might not notice risky situation, such as over heating.
Such design is hypothetical, because it is extremely impractical; it implies that the operator needs to monitor the machine state continuously. This design is used here to demonstrates the need for automation in safety-critical systems.
Updated on 08 Feb 2017.