pp39-49 of the IASI Proceedings for 2005: There are patterns repeating themselves throughout the history of aviation accidents. Studying the "types of accident cases - not necessarily investigating the accident” has the potential to contribute significantly to aviation safety research. What has basically been stated above is that aviation "professionals” in particular, accident "investigators” have been observing patterns in the causal interactions among the factors that contribute to separate accidents that have happened at different times. Identifying these patterns and using them in a hybrid expert system to assist with causal modeling of aviation accidents is the objective of this study.