How can an FTA be used qualitatively?

Fault Tree Analysis (FTA) is a systematic, graphical method used for analyzing the causes of system failures. When used qualitatively, the primary focus is to explore and identify all the factors and combinations of events that could lead to a specific undesired event or failure. This aspect of FTA allows engineers and reliability professionals to visualize how various failures interrelate and contribute to a top-level failure condition, providing insights into the safety and reliability of a system.

The qualitative approach emphasizes understanding the pathways that lead to failure without quantitatively assessing the likelihood of those failures or their consequences. This exploration of causative factors is crucial in identifying potential vulnerabilities in a system, informing risk management strategies, and guiding improvements in design and operating protocols.

This qualitative analysis aids in pinpointing which factors to address to enhance system reliability and safety, making it an essential tool in the realm of reliability engineering. While identifying failure modes, estimating repair costs, or evaluating vendor reliability are important tasks within broader reliability assessments, they do not capture the primary qualitative purpose FTA serves in exploring all contributory factors leading to a failure event.