在编制出FT后,我们已找到了引起顶上事件发生的所有原因事件,以及原因事件与顶上事件之间的逻辑关系。但是只编制FT是不够的。因为哪些基本事件同时发生时,顶上事件就必然发生从FT上不易直接看出。同时仅从FT上也不易直接看出基本事件对顶上事件发生的影响程度。故此,我们就引入了定性分析的方法来解决这些问题。FT的定性分析是排列基本事件重要顺序的分析方法,目的是找到最重要的基本事件。 After compiling the FT, we have located all the causal events that caused the top event, and the logical relationship between the causal event and the top event. However, the preparation of FT is not enough. Because of which basic events occur at the same time, the overhead event will inevitably occur from the FT is not easy to see. At the same time, it is not easy to directly see the influence of basic events on the top events from FT alone. Therefore, we introduced a qualitative analysis method to solve these problems. Qualitative analysis of FT is an analysis of the order of importance of basic events in order to find the most important basic events.