Confusion over an automation system’s current mode of operation can lead to misinterpretation of information or inappropriate actions.

As automation systems are able to complete more tasks and utilize more input sources, the automation inevitably becomes more complex. As complexity increases, the number of automation modes that a user must understand tends to increase. The increased number of modes can improve the ability of automation to assist the user with specific needs for a variety of different scenarios. However, if the automation user is unaware of the current system mode, the user may be led to misinterpret the information being provide or to provide inappropriate inputs for the current mode.

Why It's Important

Mode errors occur when the actual automation mode of a system differs from the user’s expectation. This can lead to actions that result in unexpected or unwanted consequences. The user in these scenarios is often surprised by effects of their actions and can be confused as to what is happening and what they should do to return the system to normal operations. Mode confusion has contributed to several significant aviation accidents and incidents.

Design and Implementation Considerations

The user should be able to tell what the automation is doing in an obvious and explicit way from the user’s perspective, not the designer’s. The automation system can be thought of as a member of the operational team. It must communicate to the human users and provide feedback about what it is doing and what it is about to do. The saliency of automation state indicators is an important design consideration to mitigate mode confusion and encourage monitoring. Designers and operations managers should require some participation from the user in operating systems as opposed to full passive automation to ensure that the automation is not left unmonitored. Additionally, operational procedures and staffing levels should be implemented so that the workload is never routinely high enough to discourage monitoring safety-critical automation functions.

Further Reading on Mode Confusion

Mode Awareness and Energy State Management Aspects of Flight Deck Automation – Commercial Aviation Safety Team

A Rigorous View of Mode Confusion – Jan Bredereke & Axel Lankenau

Automation Surprises – Nadine Sarter, David Woods, & Charles Billings

Learning from Automation Surprises and 'Going Sour' Accidents: Progress on Human-Centered Automation – David Woods & Nadine Sarter

Experimental Study of Vertical Flight Path Mode Awareness – Eric Johnson & Amy Pritchett