Event Pathway Maps ◾ 105
and insightful aspects of an event pathway map. Pre- existing conditions
frequently make systems vulnerable to failure and, therefore, as much as
possible, should always be identified and explained.
Once an event pathway map is developed, always ask yourself if other
parallel or “sneak” pathways could somehow develop that could later merge
with an already identified event activity node further “down- time.” Often
new pathways can cause a similar failure event, albeit with a very different
initial starting point. This is essentially what happened in Figure6.3. In this
example, the pre- existing conditions made the system more vulnerable to
failure and allowed two very different failure pathways to occur and eventu-