163: Mental Workload Issue
Definition/Typical Issues
Was the error caused by a complex situation or system? Were system controls so complex that they contributed to user error? Did the system impose unrealistic monitoring or mental processing requirements? Did a successful outcome depend upon a novel decision?
Examples
Example 1
- Eight maintenance tasks were in progress at the same time. The control room operator had to perform some steps for each of these tasks. He was to transfer the contents of tank A to tank B to support one of the maintenance tasks. While he was involved with another task, he lost track of the tank level and tank B overflowed.
Example 2
- The audible alarm on the toxic gas detector was inoperable. An operator was assigned to watch the toxic gas meters for an entire 8-hour shift to detect a toxic gas release. The operator failed to notice a release when it occurred.
Example 3
- A line had to be flushed to clear out some contaminants. This process was only performed a few times a year. No procedure was developed for this process because it was performed so infrequently. The operator used his best judgment in performing the lineup but failed to close one valve. The backflow through this line resulted in an exothermic reaction in one of the supply tanks.
Example 4
- During an upset condition, the operators misdiagnosed the situation. As a result, they implemented procedure ABN-001 instead of ABN-002.
Typical Recommendations
- Provide tools to make decision making easier and to reduce the chances of human error.
- Reduce the complexity of control systems.
- Do not place workers in situations requiring extended, uneventful vigilance.
Cross-References
| Version 10 Element(s) | |
|---|---|
| Node ID | Node Name |
| 155 | Workload |
| Maritime Element(s) | |
|---|---|
| Node ID | Node Name |
| 144 | Workload |