Leveson argues that most accident models are designed for simple systems. Newer accident models are needed because of the changing landscape of organizational systems and the changing contexts in which they are developed. Fast-paced technological change, new types of digital failure and hazards, decreasing tolerance for failure, and new regulatory standards all necessitate a new paradigm of accident model. Leveson meticulously examines older event-based models and their limitations. She argues that event-based models are often subjective and open to bias. They are poor at recognizing management or cultural factors and often do not account for personal adaptation and human error. Leveson argues for a new model based on systems theory. In this new model, safety is viewed as a is adaptive and socio-technical. Additionally, she discusses how the new model will impact accident analysis, accident prevention, risk assessment, and performance monitoring.