When making policy, procedural, or technological changes to a complex system that has safety implications, a key question decision makers must answer is: What are the risks to the users of the system that will result from making these changes to the system? This chapter illustrates a method to explore different facets of this question using mathematical modeling and probabilistic risk assessment techniques, with the objective of assessing the safety impact of changes to the National Airspace System that follow from the Federal Aviation Administration's next generation air traffic modernization program. The authors describe the development of an Integrated Safety Assessment Model as a structured approach to evaluating current and emerging risks in National Airspace System operations. This process addresses the previously stated risk question by combining fault tree and event sequence diagram modeling techniques, hazard identification and analysis methods, opinions from subject matter experts, and concepts from business intelligence.
