164: Knowledge-based Behavior Issue
Definition/Typical Issues
Was the error caused by a complex situation or system? Could better system design eliminate the error? Do personnel have to recall infrequently used information to adequately perform the task? Did the task require that personnel commit extensive amounts of information to memory? Should information have been provided on the equipment or in a procedure?
Was the error due to the need for excessive mental processing by personnel? Were personnel required to work through complicated logic sequences or other written instructions? Were personnel required to carry out mental arithmetic? Did a successful outcome depend upon a novel decision?
Were the system or equipment controls excessively complex? Could the system have been designed with simpler controls so that the chance of error was reduced?
Examples
Example 1
- During an emergency situation, more than 80% of the annunciator tiles in the control room illuminated at once. The operators on duty were used to responding to a single alarm at a time using very specific procedures. In this situation, they did not have enough specific knowledge of how the various systems interacted; therefore, they were at a loss in determining the appropriate response to the situation. As a result, the operators responded to a few alarms in the wrong priority, worsening the situation. In this case, knowledge of the overall system was required.
Example 2
- The clock on a data recording unit needed to be advanced 1 hour for the switch to daylight savings time. The process for doing this was not obvious as there were no time-set buttons on the device. No procedure or directions were available for this task either. As a result, the operator tried a number of different ways before succeeding.
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
- In order to determine the amount of acid to add to a particular mixture, an operator was required to take readings from three meters and perform a mental calculation. The operator made a mental error in performing the arithmetic and added the wrong amount of acid to the tank. As a result, the product was out of specification.
Example 5
- An operator was attempting to determine whether the present plant condition was acceptable. To do this, the operator had to determine the pressure and temperature of a vessel, then use a 20-page table to determine whether the vessel had adequate subcooling by determining the saturation temperature for the pressure of the vessel. Then he compared the vessel temperature to the saturation temperature. This task could have been simplified by using a graph, a job aid, or letting the plant process computer perform the task. This task had been performed incorrectly several times in recent months.
Typical Recommendations
- Modify system design to eliminate knowledge-based decision making.
- Ensure that enough time is provided to complete the knowledge-based decision.
- Provide tools (such as decision trees or flowcharts) to make decision making easier and to reduce chances of human error.
- Provide adequate staffing to assist in making a knowledge-based decision.
- Reduce the complexity of the control system demands on the operator.
- Provide workers with the information they need (e.g., procedures, calculated tables) instead of relying heavily on their mental capabilities (e.g., memory, mental calculations).
- Provide the information that workers need in the simplest form possible.
- Provide information in the most direct form possible. Examples include the following:
- Provide a flow rate instead of the output of a square root instrument and conversion table
- Provide a mass flow rate instead of a load cell output for a tank and stopwatch
- Provide tank level indication instead of flow rate into the tank, flow rate out of the tank, and a watch
- Provide acceptable parameter ranges (i.e., 75-85 psig) instead of error allowances (i.e., 70 psig ± 5 psig)
- Provide subcooling values rather than temperature, pressure, and subcooling look-up tables
- Anticipate the types of conditions workers may encounter and provide the information they will need under each of these conditions.
- Seek out expertise when making critical decisions.
- Appoint a technology steward for each type of process operated by the company.
- Appoint a technology steward for broader technology areas that are critical to the company, such as corrosion, inspection of fixed equipment, predictive maintenance methods, etc.
- Establish organizational processes to create, acquire, interpret, transfer, and retain knowledge.
- Ensure that those authorizing deviations from standard procedures are well aware of the hazards and have a sense of vulnerability.
- Ensure that persons authorized to approve abnormal operations have the (1) training and experience to understand a wide range of hazards and (2) knowledge of well-established methods to manage risk associated with the hazards.
Cross-References
| Version 10 Element(s) | |
|---|---|
| Node ID | Node Name |
| 158 | Knowledge-based Decision Required |
| 159 | Excessive Calculation or Data Manipulation Required |
| Maritime Element(s) | |
|---|---|
| Node ID | Node Name |
| 156 | Excessive/Complex Calculations Required |
| 157 | Knowledge-based Decision Required |