This paper presents the state-of-the-art in the process industry of Task Analysis and Operator Action Analysis. It is shown that the existing methods of analysing operator actions do not come up with the acquired demands. Furthermore it can be pointed out that research is needed to develop an analytical method to identify and evaluate those operator actions that have an effect on system reliability and availability. In a co-operation between Technische Universitat Berlin and Bayer CropScience GmbH, Frankfurt a.M., Germany, a new approach for Operator Action Analysis was developed and validated on an industrial plant. It covers both normal and abnormal situations and focuses on consequences when the operator actions are wrongly executed or not executed at all. With the new method potential errors, which could occur while operator performs tasks during normal and/or abnormal operation can be identified. Thus, necessary countermeasures can be taken to increase safety and reliability of the plant.