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• Create Date August 24, 2016
• Last Updated August 14, 2018

Bowtie analysis is a simple diagrammatic way of describing and analysing the pathways of a risk from hazards to outcomes and reviewing controls. It can be considered to be a combination of the thinking of a fault tree analysing the cause of an event (represented by the knot of a bow tie) and an event tree analysing the consequences (ISO 31010:2009).

However, the focus of the Bowtie is on the barriers between the causes and the risk and the risk and consequences. Bow Tie diagrams can be constructed starting from fault and event trees, but are more often drawn directly from a brainstorming session.

Bowtie analysis is used when the situation does not warrant the complexity of a full fault tree analysis or when the focus is more on ensuring that there is a barrier or control for each failure pathway. It is useful where there are clear independent pathways leading to failure.  A bow tie is often easier to understand than fault and event trees and hence can be a useful communication tool where analysis was achieved using the more complex techniques (ISO 31010:2009).