The visibility of an irrelevant control contributes to the operators awareness of the control, but it might distract the operators when looking for a control they need. Hiding the irrelevant controls facilitate the operators' orientation in the current situation, but hampers the operators awareness of the existence of the irrelevant control

This chart presents the resolution of the control visibility dilemma . It shows that the visibility of irrelevant controls should depend on the situation:

• In routine operation, it may be visible. This will help the operators become accustomed to the control
• When under latent hazard, they might distract the operators attention from the main task, which is to be aware of the hazard.
• When under hazard, they may be visible, as long as the risk is not acute.
• When under threat, they should be hidden, to prevent interference with the relevant controls.

Updated on 19 Mar 2017.