• software disasters;
  • mars polar lander;
  • patriot missile;
  • Therac-25;


Over the years, there have been several major software disasters, resulting from poor software project management, poor risk assessment, and poor development and testing practices. The results of the disasters range from project delays, project cancelations, loss of millions of dollars of equipment, to human fatalities. It is important to study software disasters, to alert developers and testers to be ever vigilant, and to understand that huge catastrophes can arise from what seem like small problems. This paper examines such failures as the Mars Polar Lander, the Patriot missile, and the Therac-25 radiation deaths. The focus of the paper is on the factors that led to these problems, an analysis of the problems, and the lessons to be learned that relate to software engineering, safety engineering, government and corporate regulations, and oversight by users of the systems. A model named STAMP, Systems-Theoretic Accident Modeling and Process, will be introduced, as a model to analyze these types of accidents. This model is based on systems theory, where the focus is on systems taken as a whole, as opposed to traditional failure-event models where the parts are examined separately. It is by understanding the past, that we can improve the future. Copyright © 2010 John Wiley & Sons, Ltd.