Reviewing and Maintaining BowTie Models

As with any risk assessment methodology, bowties should be reviewed and updated periodically to:

• Ensure they remain relevant following changes to the organisation, operation, or operating environment.
• Reflect lessons identified through safety intelligence and other relevant information sources.
• Validate or revise assumptions made during the original bowtie development process.

An effective review process helps ensure bowties remain active representations of the risk landscape, supporting informed decision-making, appropriate risk management strategies, and targeted resource allocation.

What to review

Information sources

Consider whether any new information should be incorporated into the bowtie, including:

• Safety Performance Indicators (SPIs)
• Changes to the operating environment (e.g. equipment, procedures, operating practices, or emerging technologies).
• Changes to the organisational structure (e.g. restructuring of safety responsibilities and accountabilities)
• External information from relevant industry or state bodies (e.g. awareness of issues not necessarily encountered first hand but nonetheless relevant)

Threats

Consider:

• Are there new threats that should be considered
• Are existing threats no longer relevant.?
• Has the exposure to the Threats changed?

Controls

Consider:

• Have any controls been introduced, modified, or removed?
• Are there changes to how the threats or escalation factors are being managed (e.g. have any controls been modified, created or removed)?
• Are there changes to the post holders accountable for the controls?
• Are the control effectiveness ratings still valid?

Escalation factors

Consider:

• Do the escalation factors remain an appropriate representation of the significant issues requiring active management?

• Do any escalation factors identify underlying management system weaknesses that should be addressed through existing assurance or improvement activities?

Note: The purpose of including escalation factors within a bowtie is to identify issues that may reduce the effectiveness of controls and therefore require active monitoring and management. During the review process, organisations should consider not only the addition of new escalation factors, but also the removal of those that are no longer relevant.

Consequences

Consider:

• Has the nature of the consequences changed?
• Is the likelihood or impact of the consequence changed given the review of the other diagram elements (e.g. have the risk matrix inputs changed)?

When to review

According to the existing SMS details regarding risk assessment reviews.

For example:

• Reactively, following a significant incident or accident.
• Proactively, as per a scheduled review program (e.g. annually).
• Predictively, trend analysis based on future failure.

How to review:

According to the existing SMS details regarding risk assessment reviews.

For example:

• Facilitated workshop with relevant SMEs.
• Distribution of results according to stakeholders and significance.