Operators´ reliance on automation during the control of a semi-automatic process

The authors investigate how operators interacted with a simulated semiautomatic pasteurization system and discuss how operators interacted with automation preceding severe accidents. When disturbances affected operators´ ability to contol the system manually very few switched to automatic control; instead, they maintained manual control even when it led to a catastrophic failure. Conversely, when faults made automatic control impossible, operators switched to manual control. Considering that the same number of keystrokes was required for both manual control commands and engaging the automation, the persistent use of manual control was not caused by the demands of engaging the automatic control. Instead, it seems that operators displayed a bias towards persisting with manual control. These results suggest that operators may effectively intervene and adopt manual control to mitigate the effects of a faulty automatic controller, but that they may fail to engage automatic control when difficulties are encountered with manual control