History and Use of BowTie

The origins of bowtie are to be found in a simplified fusion of fault and event tree methodologies.

In the 90’s the oil and gas industry founded and developed the practical application of bowtie as a tool to facilitate a better understanding of how risks were being overseen and managed. The benefits of the methodology have since been recognised in numerous other industries including defence, medical, finance and the aviation industry.

A barrier-based approach to risk

The aviation community are mostly familiar with Prof James Reason’s model, referred to as ‘Swiss cheese’ and the bowtie is a barrier-based structure illustrating this approach. This method is also referred to in ICAO’s Safety Management Manual (SMM) document referencing defensive barriers in accident causation with ICAO Annex 19 referring to understanding and appreciating safety risk controls

Bowtie achieves this by not only identifying the controls (or barriers) in place but also looking at control failure mechanisms (as escalation factors) and in turn how these are managed (as escalation factor controls). Based on these considerations, insights are gained into the organisation’s risk mitigation strategies and therefore into the appropriate management of safety resources.

The main strength of the barrier approach is as a qualitative tool, which is a practical solution for the challenges of risk assessment in the dynamic operating environments of the aviation industry.

The barrier approach of the bowtie, while most often used as a proactive risk assessment tool, may also be of benefit for the reactive classification of safety events as evidenced by the development of the Aviation Risk Management Solutions (ARMS) Safety Issue Risk Assessment (SIRA) tool.

BowTie is an adaptable risk management tool that can be applied across a wide range of sectors and operational environments within aviation and beyond.

BowTie is currently used throughout the UK and internationally by a broad range of aviation organisations, including (but not limited to):

·         Airport operators

·         Air Navigation Service Providers (ANSPs)

·         Large and small aircraft operators (fixed-wing and rotary-wing)

·         Ground service providers.

·         Military aviation organisations

·         National Aviation Authorities (NAAs)

The CAA Approach to BowTie

The CAA's bowtie journey began with the development of a series of BowTies focused on the Authority's significant seven BowTies and associated aviation safety risks. These models were developed collaboratively with CAA specialists and industry subject matter experts, providing a practical framework to support safety risk discussions across the aviation sector.

The resulting BowTies have helped promote a shared understanding of aviation safety risks and supported safety improvement activities both within the UK and internationally. As aviation safety priorities evolve, these models are reviewed and updated to reflect emerging risks and alignment with the European Union Aviation Safety Agency (EASA) and CAA Key Risk Areas, helping to ensure they remain relevant and effective in supporting risk and performance-based decision-making.

Note: As part of the ongoing review and redevelopment of the Significant Seven bowties, the downloadable bowtie templates are no longer actively maintained and may not reflect the latest versions of the CAA risk models.