Mission Ready Software

Software fault tree analysis training class

Fault trees are an effective means to identify unknown hazards in a system.  This is a top-down analysis that complements the Failure Modes Effects Analysis which is conducted from the bottom-up viewpoint.  Fault trees are useful for emerging technology or for identifying the root cause of a field issue that is difficult to reproduce.

Fault trees are most effective when a system is relatively new or has recently upgraded and the hazards aren’t yet understood. It’s also effective when there are known hazards that are likely due to software and the root causes need to be identified.

This fault tree analysis course covers how to add software to a system fault tree. The basic process for conducting the software FTA is shown below. Contrary to popular belief, software failure modes should be worked into a system-level software fault tree as opposed to analyzing software faults in a vacuum.  Another common but faulty approach is to treat the software as a black box.  For the software FTA to be effective the software must be analyzed from a functional as opposed to a black-box perspective. 

For example – it’s ineffective for the fault tree to have an event that says “Software failed”.  That’s an example of a black-box approach which is common but largely useless.  The effective approach is to analyze how the software will fail in specific terms.  Example:  “The software inadvertently allowed ”.  The software fault tree analysis training covers the methods employed for constructing a system fault tree with software failure modes.