System Theoretic Safety Analysis of the Sewol-Ho Ferry Accident in South Korea by Yisug Kwon
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System Theoretic Safety Analysis of the Sewol-Ho Ferry Accident in South Korea by Yisug Kwon B.S. Mechanical Engineering, Kumoh National University, Kyungbuk, S. Korea, 1992 M.S. Mechanical Engineering, Kumoh National University, Kyungbuk, S. Korea, 1995 Ph.D. Mechanical Engineering, Pusan National University, Pusan, S. Korea, 2005 Submitted to the System Design and Management Program in Partial Fulfillment of the Requirements for the Degree of Master of Science in Engineering and Management at the Massachusetts Institute of Technology February 2016 © 2016 Yisug Kwon All rights reserved The author hereby grants to MIT permission to reproduce and to distribute publicly paper and electronic copies of this thesis document in whole or in part in any medium now known or hereafter created. Signature of Author ________________________________________________________________________________ Yisug Kwon System Design and Management Program December 2015 Certified by _________________________________________________________________________________________ Nancy G. Leveson Thesis Supervisor Engineering Systems Division Accepted by _________________________________________________________________________________________ Patrick Hale Director System Design and Management Program System Theoretic Safety Analysis of the Sewol-Ho Ferry Accident in South Korea by Yisug Kwon Submitted to the System Design and Management Program in December, 2015 in Partial Fulfillment of the Requirements for the Degree of Master of Science in Engineering and Management ABSTRACT The disaster of the Sewol-Ho, which took place on April 16, 2014, was one of the worst maritime disasters in South Korea in decades, and rescuing only 172 of a total 476 people triggered thorough accident investigations. As the results of the investigations performed by the Korea Maritime Safety Tribunal and the Board of Audit and Inspection of Korea, 399 people were blamed for the accident and arrested, 154 of them were put in jail, many safety policies and manuals were found inadequate, new safeguards against the kinds of accidents were implemented, and Korean high and low governments’ structures which were related to the accident were reorganized: disbanding the 61-year-old Republic of Korea Coast Guard and establishing a new Ministry responsible for Korean public safety. The accident investigation reports, however, were limited in revealing the most important systemic causal mechanisms leading to a more complete understanding of the reason why the accident occurred, and therefore, appear to be inadequate in designing and obtaining sociotechnical system level safety because they did not apply system engineering tools in the investigations. The Systems-Theoretic Accident Model and Processes (STAMP), created by Dr. Nancy Leveson, is an accident model based on systems theory. It has been applied to improve system safety in a number of complex sociotechnical systems. STAMP has the capability to help identify a broader set of systemic causal factors and develop and improve the safety control structure for the entire maritime transportation safety structure. This thesis applies the Causal Analysis based on Systems Theory (CAST) accident analysis tool created by Dr. Leveson to the accident and provides the application and findings of CAST. The CAST analysis demonstrated that a complete set of systemic causal factors was identified by the systems theory approach, which was much broader than those of the Korea Maritime Safety Tribunal and the Board of Audit and Inspection of Korea. The powerful and effective tool to reveal the systemic causal mechanism led to the identification of the systemic causal factors and system improvements of the safety control system. Thesis Supervisor: Nancy G. Leveson Title: Professor of Aeronautics and Astronautics and Engineering Systems Yisug Kwon MIT SDM Thesis 2 Acknowledgements “If I speak in the tongues of men and of angels, but I do not have love, I am a noisy gong or a clanging cymbal (1Co 13:1). Love is patient, love is kind, it is not envious. Love does not brag, it is not puffed up. It is not rude, it is not self-serving, it is not easily angered or resentful. It is not glad about injustice, but rejoices in the truth. It bears all things, believes all things, hopes all things, endures all things (1Co 13:4-7). I would first like to thank God for the great opportunity to learn. I would like to thank Dr. Leveson, as my thesis supervisor, for contributing to my understanding of STAMP and guiding me along the way. At her class, ESD355 Engineering of software, in the fall, 2013, Dr. Leveson claimed that Safety is a system property. It must always be analyzed top-down and for the system as a whole. When putting two or more existing components (“systems”) together, the emergent properties must be analyzed for the integrated system. Calling that larger system a “System of systems” may be misleading by implying that emergent properties can be treated differently than any other system or different system engineering techniques can be used (Leveson, 2013). This claim challenged me to know more about system engineering and STAMP, and start my thesis research. I would like to thank the MIT SDM program, including the faculty, staff, and cohort. Special thanks to Pat Hale who welcomed me to the 1-year SDM Certificate program and later, this SDM Master program, and has been a great supporter along the way. To my sponsor company and its great people, I would like to thank you, especially Dan, Randy, and Jinho for supporting me to get through this SDM program. I am especially thankful to Lim, Rana whose full support and encouragement allowed me to enjoy this program at MIT, and to my angels, Jungtaik, Sungtaik and Euntaik. I would like to express my deepest sympathy to the families for the losses in the accident. Yisug Kwon MIT SDM Thesis 3 Table of Contents ABSTRACT ............................................................................................................................................................... 2 Acknowledgements .............................................................................................................................................. 3 List of Acronyms .................................................................................................................................................... 6 Chapter 1: Introduction ...................................................................................................................................... 7 Motivation ......................................................................................................................................................... 7 Objective ......................................................................................................................................................... 10 Overview ........................................................................................................................................................ 10 Chapter 2: Literature review ......................................................................................................................... 11 STAMP (Systems-Theoretic Accident Model and Processes) .................................................... 13 Causal Analysis based on STAMP or CAST ........................................................................................ 23 Chapter 3: Summary of the Sewol-Ho Accident (Oh, 2015) .............................................................. 25 Chapter 4: Korea Maritime Safety Tribunal (KMST) Root Cause Analysis .................................. 34 Contributing Factors to the capsizing of the ferry: ........................................................................ 34 Contributing Factors to not rescuing all people from the distressed ferry: ........................ 35 Root Causes of the capsizing of the ferry: ......................................................................................... 35 Root Causes of not rescuing all people from the distressed ferry: .......................................... 36 Recommendations related to the capsizing of the ferry:............................................................. 37 Recommendations related to not rescuing all people from the distressed ferry: ............. 37 Chapter 5: Board of Audit and Inspection of Korea (BAI) Root Cause Analysis ........................ 39 Contributing Factors to the capsizing of the ferry: ........................................................................ 39 Contributing Factors to not rescuing all people from the distressed ferry: ........................ 41 Root Causes of the capsizing of the ferry: ......................................................................................... 42 Root Causes of not rescuing all people from the distressed ferry: .......................................... 43 Recommendations related to the capsizing of the ferry:............................................................. 43 Recommendations related to not rescuing all people from the distressed ferry: ............. 43 Chapter 6: CAST ANALYSIS ............................................................................................................................ 44 CAST Step 1: Identify the System(s) and Hazard(s) Involved in the Loss ............................ 45 Yisug Kwon MIT SDM Thesis 4 CAST Step 2: Identify the System Safety Constraints and Requirements with the hazards ...........................................................................................................................................................................