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UK Civil Aviation Regulations

These are published by the CAA on our UK Regulations pages. EU Regulations and EASA Access Guides published by EASA no longer apply in the UK. Our website and publications are being reviewed to update all references. Any references to EU law and EASA Access guides should be disregarded and where applicable the equivalent UK versions referred to instead.

Experience has shown that the most effective format for building the bowtie is within a facilitated workshop.

As with any risk assessment it is essential to have input from the relevant subject matter experts (SMEs) in order to identify the important issues and produce an assessment that is a realistic representation. For example, when looking at the risk of a runway incursion event, it is good practice to involve all the relevant parties who can contribute to preventing it. This would therefore involve airline operators, ANSP and airport operators.

Why involve other parties?

  • Provides a more comprehensive risk picture
  • Understanding of roles between different stakeholders in mitigating the shared risk
  • Identifies any potential transfer of risk between different stakeholders
  • Illustrates actions that has the most impact on the risk (which may be directed at the other stakeholders)
  • The challenge then becomes the distillation of the SME knowledge into the appropriate bowtie format in a consistent and understandable way. An experienced bowtie facilitator is an invaluable tool in this regard

An experienced facilitator can also be of benefit to the process by encouraging free discussion whilst avoiding bias towards specific individual issues and keeping discussions on track.

Practical Steps Involved in Conducting a Bowtie Based Risk Assessment

  • Assign a project leader for the bowtie (usually the workshop facilitator).
  • Develop initial context/scope and review the existing safety information.
  • Prepare the bowtie hazard and top event definitions as a starting point for the workshop.
  • Identify and organise the required SMEs.
  • Conduct a workshop with the SMEs using an experienced bowtie facilitator. Work through the eight basic elements of the bowtie (as described in the bowtie elements section).
  • Assign and link additional information (e.g. control effectiveness, control criticality, threat exposure etc) to the diagram elements according to your specific goals (see how to identify safety and risk priorities).
  • Perform a critical review/ validation of the bowtie model at a separate workshop session.
  • Communicate results as appropriate and incorporate the information according to the functions within the SMS.