The prediction of the behavior of complex systems remains a costly and time consuming activity due to their data intensive nature. Such dynamic systems do not always lend themselves to a quantitative behavioral analysis. An impact analysis is a novel qualitative approach aimed at determining how a system element deviates from a pre-defined “normal” operational mode due to a change in the operation of another element existing within the same architecture, or due to an interaction with an external environmental condition. This qualitatively determines the elements in the system that would be affected by a modification, and can aid in system development by identifying relationships and interdependencies prior to implementation. An agent based modeling approach is used to create the analysis tool for determining impact within the system. The paper presents an agent based impact analysis applied to a sample United Kingdom Air Traffic Management system as a means of validating the model and approach. The analysis data is validated against data collected from the real world ATM system. The results from the test case vindicated the assumptions made and also identified a number of areas for further development. The capability of impact analyses and the potential for application to complex architectures appears promising based on the results.