Providing Information and Feedback

Designing feedback in general was covered in section 9.3.2. This section covers feedback design principles specific to human controllers. Important problems in designing feedback include what information should be provided, how to make the feedback process more robust, and how the information should be presented to human controllers. 

Hazard analysis using STPA will provide information about the types of feedback needed and when. Some additional guidance can be provided to the designer, once again, using general safety design principles. 

The state of the controlled process This information is used to (1) update the controllers process models and (2) to detect faults and failures in the other parts of the control loop, system, and environment. 

The effect of the controllers actions This feedback is used to detect human errors. As discussed in the section on design for error tolerance, the key to making errors observable—and therefore remediable—is to provide feedback about them. This feedback may be in the form of information about the effects of controller actions, or it may simply be information about the action itself on the chance that it was inadvertent. 

Updating process models requires feedback about the current state of the system and any changes that occur. In a system where rapid response by operators is necessary, timing requirements must be placed on the feedback information that the controller uses to make decisions. In addition, when task performance requires or implies need for the controller to assess timeliness of information, the feedback display should include time and date information associated with data. 

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It should be highlighted that the person responsible for the observation and registration procedure, adopted in each of the observations, an approach to encourage the involvement of workers, seeking to explore with them reasons for non-use, to raise awareness of the effects of noise exposure and providing information and feedback on how the protectors should be placed and on maintenance instructions. Some workers, for example, reported that the involvement of not using the hearing protectors was due to the fact that the only size available in the company wasn t the appropriate for you, and the person responsible for the action took steps to resolve internally this issue. 

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