Rapid development of an event tree modeling tool using COTS software

This paper introduces a simple and powerful event tree modeling tool called EC Tree, which was developed using Microsoft Excel and Visual Basic. The tool enables the rapid construction of event trees of any complexity through easy-to-use templates, menu items, and shortcut keys. EC Tree was developed to facilitate the rapid generation of event trees for application to event based risk analyses, specifically for use in NASA's IM&S (Integrated Modeling and Simulation) team. In contrast to many other event tree modeling tools, EC Tree does not require the purchase or installation of any specialized software, other than Microsoft Office, and is simple enough for a risk analyst to use immediately, without training. Further, EC Tree was created as a generic event tree modeling tool and is thus not restricted to specific systems, domains of relevance, or scope. This paper describes EC Tree, its functionality, and the development process employed. Specific focus is given to the process of rapid prototyping, programming, testing, and software release used during the development of EC Tree, and on lessons learned. The general approach of using COTS software as a basis for rapid software development is also discussed along with the limitations of this approach. Some potential applications of EC Tree to model event based processes in the aerospace field are also discussed