The Bow-tie Method


The bow-tie can be used to help simplify risk assessment by allowing one to conceptualise the interaction of causes, controls and consequences of a risk. The following diagram illustrates the process.

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Risk Analysis using Bow-Ties
The steps to undertaking a risk analysis using the bow-tie method are as follows:

  • Of all the possible consequences resulting from the risk (these are the yellow boxes above), identify which is the most foreseeable, as opposed to the worst-case


  • Identify the consequence level of the most foreseeable consequence


  • Identify the likelihood level of the risk occurring and resulting in the consequence identified in Step 1

Example: Kitchen Fire

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In this case, we might identify that the most foreseeable consequence of a kitchen fire would be asset destruction. Our analysis would thus be:

  • What is the consequence of asset destruction due to fire?


  • What is the likelihood that there will be a fire which causes asset destruction?

By constructing a bow-tie diagram, one can simply see how multiple causes with failed preventative controls result in a risk occurring. If the preparedness controls also fail, the risk will occur and have a negative consequence. Mapping risks using the bow-tie can provide a sound starting point from which to ensure controls are actually addressing the real causes and consequences.