Major process accidents continue to occur with the advancement of modern process systems. Major process accidents should not be viewed as Black Swan and can be predicted and prevented. This article investigates the characteristics of process accidents. Based on which, a method for the diagnosis and classification of accidents is proposed. The proposed tool is applied to the Bhopal accident and the swine flu event. The case studies verify the effectiveness and applicability of the proposed tool. To tackle major process accidents, conventional risk assessment, and management approaches are inapplicable without adaption. Enormous research work is needed to develop new generation of methods and tools that enable safer process systems and operations. Knowledge and technological gaps are identified in this perspective. (C) 2017 American Institute of Chemical Engineers