An integrated Operator Advisor System (OAS) has been built using generic task methodology. The operator’s activities of plant monitoring, data interpretation, procedure execution, and diagnosis have been implemented as the four generic tasks in the system. The OAS is capable of identifying the abnormal functioning of the plant in terms of threats to safety, preenumerated abnormal events, and deviations from normality. After the identification of abnormal functioning, the system will identify the procedures to be executed to mitigate the consequences of abnormal functioning and will help the operator by displaying the procedure steps and monitoring the success of actions taken. The system also is capable of diagnosing the cause of abnormal functioning. The diagnosis is done in parallel to the task of procedure execution. The system is designed to operate in real time and can change its focus of attention depending on current priorities. The system also is designed to provide defense-in-depth in situations when there are no available procedures or the available procedures cannot be successful. The OAS has been tested with a scenario and a limited number of procedures for abnormal events and safety threats. The system responds as expected according to the procedures and knowledge incorporated in it.