Step 1: Define the Hazard

Step 1 is to identify the hazard. The hazard provides the context for the BowTie and represents the condition, activity, object or situation that could contribute to an aircraft incident or accident.

Hazard often describes a normal aspect of an operation or activity within the operating environment and helps define the context and scope of the BowTie. For example, driving a car on a busy motorway is an activity where an individual is exposed to a range of risks.

A hazard may be focused on:

·       A condition (e.g. icing conditions)

·       An object (e.g. another vehicle)

·       An activity (e.g. driving)

Hazards are often inherent to normal operations and are not necessarily something that can, or should, be eliminated. Instead, they are managed through appropriate risk controls.

A single hazard may be associated with multiple top events. For example, the hazard of driving on a motorway could lead to several different loss-of-control events, such as a vehicle leaving its lane, a loss of braking capability, or a collision with another vehicle. Each of these top events could be represented by a separate BowTie model.

Definition

A condition, situation, activity or object that could cause or contribute to an aircraft incident or accident.

Guiding principles

·       When describing the hazard, ensure it establishes the context and scope of the BowTie, defining the environment in which the threats and controls exist.

·       The scope of a BowTie can be thought of as adjusting the zoom on a camera. A broad scope captures the wider operational picture, while a narrow scope focuses on a specific area of concern.

·       It is often helpful to start with a broader view. If the resulting BowTie does not provide sufficient detail to support decision-making, revisit the hazard and top event definitions and refine the scope accordingly

Traps and tips

Trap: When reviewing an organisation's existing hazard register, confusion can arise between what constitutes a hazard and what constitutes a threat. Traditional hazard registers do not typically distinguish between these concepts, and entries may contain a mixture of both.

Tip: It is common to find both hazards and threats recorded within a traditional hazard register, although there is often a tendency for entries to describe threats rather than hazards. Remember that the hazard provides the context for the BowTie and sets the scene for a risk assessment that will consider multiple threats leading to a top event.

Trap: Creating BowTie diagrams that become so large and complex that their value as a communication tool is diminished.

Tip: Keep the BowTie proportionate to its purpose and ensure it remains clear, readable, and practical to use. For example, if a hard copy is required, A0 is often the largest practical paper size. Excessively large BowTies may result in text becoming illegible when printed.

Tip: If the diagram continues to grow in size, revisit the hazard, top event, and threats. Consider refining the scope to a specific aspect of the risk and using linked BowTies to represent related risk pathways. This approach can provide a holistic view of the risk while ensuring each BowTie remains clear, proportionate, and effective.