Bowtie Analysis

Bowtie analysis is a visual risk assessment method that maps the relationship between threats that could cause an undesired event, the event itself (the “top event”), the consequences that could follow, and the barriers (controls) that prevent or mitigate each pathway. In PlaneConnection, bowtie diagrams are linked to hazard register entries and provide a structured, visual complement to the 5x5 risk matrix.

Methodology

The bowtie diagram gets its name from its shape. The top event sits at the center. Threats fan out to the left, consequences fan out to the right, and barriers are placed on the lines connecting them — forming a bowtie shape.

  Threat 1 ──[Preventive Barrier]──╮                    ╭──[Recovery Barrier]── Consequence 1
                                   │                    │
  Threat 2 ──[Preventive Barrier]──┤   ┌────────────┐   ├──[Recovery Barrier]── Consequence 2
                                   ├───│ TOP EVENT  │───┤
  Threat 3 ──[Preventive Barrier]──┤   └────────────┘   ├──[Recovery Barrier]── Consequence 3
                                   │                    │
  Threat 4 ──[Preventive Barrier]──╯                    ╰──[Recovery Barrier]── Consequence 4

Component	Position	Purpose
Threats	Left side	Causal factors that could lead to the top event if barriers fail.
Top Event	Center	The pivotal undesired event — the point where control is lost.
Consequences	Right side	Potential outcomes if the top event occurs and recovery barriers fail.
Preventive Barriers	Left side (between threats and top event)	Controls that prevent threats from causing the top event.
Recovery Barriers	Right side (between top event and consequences)	Controls that mitigate or limit consequences after the top event occurs.

Threat Identification

Threats are the causal factors on the left side of the diagram. Each threat represents a distinct pathway that could lead to the top event.

Field	Type	Description
`description`	Text	Clear statement of the threat.
`category`	Enum	Classification: `human`, `technical`, `organizational`, or `environmental`.
`likelihood`	Enum	Assessed likelihood: `rare`, `unlikely`, `possible`, `likely`, or `almost_certain`.
`order_index`	Integer	Display order on the diagram.

Identify threats by asking: “What could cause this top event?” Use multiple categories to ensure you capture human factors, technical failures, organizational gaps, and environmental conditions.

Consequence Mapping

Consequences are the potential outcomes on the right side of the diagram. Each consequence represents what could happen if the top event occurs and recovery barriers are insufficient.

Field	Type	Description
`description`	Text	Clear statement of the consequence.
`severity`	Enum	Assessed severity: `negligible`, `minor`, `major`, `hazardous`, or `catastrophic`.
`category`	Enum	Impact domain: `safety`, `operational`, `financial`, or `reputational`.
`order_index`	Integer	Display order on the diagram.

Barriers

Barriers are the controls that either prevent the top event from occurring (preventive) or limit the consequences after it occurs (recovery). Barriers are the actionable core of the bowtie analysis.

Field	Type	Description
`description`	Text	What the barrier does and how it reduces risk.
`barrier_type`	Enum	`preventive` (blocks threats from causing the top event) or `recovery` (mitigates consequences after the top event).
`barrier_category`	Enum	Control classification: `engineering`, `administrative`, `ppe`, or `procedural`.
`effectiveness`	Enum	Current assessment: `effective`, `partially_effective`, `ineffective`, or `not_assessed`.
`linked_threat_id`	Reference	Which specific threat a preventive barrier blocks.
`linked_consequence_id`	Reference	Which specific consequence a recovery barrier mitigates.
`cpa_id`	Reference	Linked CPA if the barrier is being implemented or verified through a corrective action.

Barrier Effectiveness Assessment

Barrier effectiveness is assessed on a four-point scale:

Rating	API Value	Description	Action Required
Effective	`effective`	Barrier consistently performs as intended. Evidence of effectiveness exists.	Continue monitoring.
Partially Effective	`partially_effective`	Barrier works under some conditions but has known gaps or limitations.	Document limitations. Plan improvements.
Ineffective	`ineffective`	Barrier does not prevent or mitigate the pathway it is assigned to.	Immediate action required — create CPA or replace barrier.
Not Assessed	`not_assessed`	Barrier has not yet been evaluated for effectiveness.	Schedule assessment.

An ineffective barrier on a high-severity consequence pathway represents an unacceptable risk. Create a CPA to address the gap immediately (14 CFR 5.55).

Bowtie Statuses

Status	API Value	Description
Draft	`draft`	Bowtie created but not yet reviewed or finalized. Threats, consequences, and barriers may be incomplete.
Active	`active`	Bowtie reviewed and in use for ongoing risk management. Barriers are being monitored.
Archived	`archived`	Bowtie no longer actively monitored. The associated hazard may be closed or the analysis superseded.

When to Use Bowtie vs. 5x5 Risk Matrix

Both the bowtie diagram and the 5x5 risk matrix are available in PlaneConnection. They serve different purposes and are most effective when used together.

Criterion	5x5 Risk Matrix	Bowtie Analysis
Purpose	Quantify risk level (severity x likelihood) and determine acceptability.	Visualize causal pathways, consequences, and the specific barriers that manage each pathway.
Best for	Initial risk screening, prioritization, residual risk comparison.	Complex hazards with multiple threats or consequences, barrier gap analysis, communicating risk to stakeholders.
Output	Risk score and zone (green/yellow/red).	Visual diagram showing threats, barriers, top event, and consequences.
Regulatory use	Required for SRM (14 CFR 5.55).	Recommended for complex hazards. Supports 14 CFR 5.53 system analysis.
When to add	Every hazard in the register.	High-risk hazards, hazards with multiple causal pathways, or when existing barriers need systematic review.

Start with the 5x5 matrix to score the hazard. If the risk is in the yellow (ALARP) or red (Unacceptable) zone, create a bowtie analysis to map the threat and consequence pathways and identify where barriers are weak or missing.

Linked Records

A bowtie analysis connects to other SMS records:

Linked Record	Relationship
Risk assessment	The hazard that the bowtie analyzes.
CPAs	Corrective and preventive actions implementing or verifying barriers.
Investigations	Investigations that identified threats or barrier failures.

Regulatory Alignment

Part 5 Section	Requirement	Bowtie Component
5.53	System analysis and hazard identification	Threat identification and causal pathway mapping.
5.55(a)	Safety risk analysis	Threat likelihood, consequence severity assessment.
5.55(c)	Risk controls	Preventive and recovery barriers with effectiveness tracking.
5.71	Safety performance monitoring	Ongoing barrier effectiveness monitoring.
5.97	SMS records	Bowtie diagrams retained as part of hazard documentation.

Conduct a Bowtie Analysis

Step-by-step guide to creating a bowtie diagram.

Risk Matrix

Severity and likelihood definitions used alongside bowtie analysis.

Hazard Register

The hazard records that bowtie analyses are linked to.

CPA Lifecycle

How CPAs implement and verify bowtie barriers.

SMS Reference

SmartScore

Operations Reference

FBO Reference

Maintenance Reference

Operational Reports

Portal Reference

Platform Reference

API Reference

Methodology

Threat Identification

Consequence Mapping

Barriers

Barrier Effectiveness Assessment

Bowtie Statuses

When to Use Bowtie vs. 5x5 Risk Matrix

Linked Records

Regulatory Alignment

Conduct a Bowtie Analysis

Risk Matrix

Hazard Register

CPA Lifecycle

​Methodology

​Threat Identification

​Consequence Mapping

​Barriers

​Barrier Effectiveness Assessment

​Bowtie Statuses

​When to Use Bowtie vs. 5x5 Risk Matrix

​Linked Records

​Regulatory Alignment

​Related

Conduct a Bowtie Analysis

Risk Matrix

Hazard Register

CPA Lifecycle

Methodology

Threat Identification

Consequence Mapping

Barriers

Barrier Effectiveness Assessment

Bowtie Statuses

When to Use Bowtie vs. 5x5 Risk Matrix

Linked Records

Regulatory Alignment

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