Bow-Tie Diagram for Bird Strikes
diagram_BowTie_Ptaki-BirdStrike_20170706_v1-0.pdf699.19 KB
Bow-Tie Diagram for DGR (Dangerous Goods)
diagram_BowTie_DGR-Dangerous-Goods-_20190604_v1-0.pdf535.07 KB
The Bow-Tie method was developed, among other reasons, for easy-to-understand and transparent graphical presentation of safety risk scenarios. It is one of many available ways of presenting barrier models that allow gradual and targeted elimination or isolation of dangers (or/and its sources) and minimizing the effects of adverse events, helping to identify the most effective preventive and corrective actions, and in management of risks. This method is oriented on the effectiveness of preventive and / or corrective barriers applied against identified threats, and it focuses / draws attention to factors affecting the functioning of these barriers.
The main advantage of the Bow-Tie method is the visualization of individual roles, tasks, procedures and risk mitigation processes. The diagram allows to look at organizational processes through the prism of referring them to the previously identified threats. The method is also used in the process of examining real occurrences and conducting safety audits.
Figure. Basic Bow-Tie diagram
Bow-Tie combines the fault tree (left side of the diagram) and the event tree (right side of the diagram) into one risk scenario. The process of diagram development / construction requires proper definition of its individual elements. The first of these is the hazard, the object or conditions with the potential to cause losses. This is a basic element of the standard risk management process. The hazard is inextricably linked to the critical moment (Top event) in the cause and effect chain, when it comes to exceeding the established safety margin, and losing control over the hazard (Threat). These elements form the central part of the diagram.
On the left side of the diagram are indicated Threats - factors, which directly initiate the occurrence of the culmination moment associated with a specific threat. In order to prevent critical moments from occurring, so called Preventive Barriers are defined for each of its causes. These methods or measures may be compromised by certain escalation factors. Methods of controlling escalation factors can also be managed - by using the next level of barriers (Escalation factor barrier).
On the right side of the diagram are indicated the consequences (Consequence) of the climax in the conditions of the identified threat. Consequences are the unwanted result of the initiating event. Similarly as in the case of the left side of the diagram, some measures and methods of risk control can also be applied to the consequences. These are barrier barriers (Recovery barrier). They have the task of eliminating or limiting the negative impact of consequences. These barriers are also exposed to their effectiveness. The rules for indicating such escalation factors and the next level of barriers are the same as for the left side of the diagram.
The Civil Aviation Authority uses the Bow-Tie method to control from the perspective of the aviation system the areas of threats defined in the State Safety Plan for Civil Aviation. We encourage you to implement the proposed preventive and corrective barriers in the context of the indicated threats in your management systems. We are also counting on cooperation and suggestions on your part in the field of updating and improving the proposed solutions in order to better adapt them to national conditions. Below you will also find a presentation which explains in more detail how the Bow-Tie tool works. Please send any comments to the address: