EWaSAP: An early warning sign identification approach based on a systemic hazard analysis

Early warning signs and signals are perceivable sets of data which indicate in a timely manner the presence of flaws and threats to a system. Unfortunately, the structured identification and analysis of early warning signs is not readily supported by conventional hazard and risk analysis approaches. To address this problem, the STAMP Based Process Analysis (STPA) has been extended to incorporate the identification of early warning signs. The result is the Early Warning Sign Analysis based on the STPA (EWaSAP) approach. EWaSAP is described in this paper as well as the results of a case study using it in a critical process at a real world drinking water treatment works. After using EWaSAP, a significant increase on the predefined list of early warning signs was noted. (C) 2013 Elsevier Ltd. All rights reserved.