Major Accident Hazard Understanding

Educating industry on Major Accident prevention

A Major Accident Hazard is a source of danger that has the potential to cause a major incident, whether that involves multiple fatalities and/or significant damage to plant, equipment or the environment. Managing Major Accident Hazards is vital to safe operations. Everybody working in the oil and gas industry, both onshore and offshore, has a part to play in managing these hazards.

To control Major Accident Hazards, barriers must be put in place. These barriers help prevent a Major Accident happening or mitigate the effects of a Major Accident if one were to occur. To help those working in the industry identify the barriers and understand the part they play in ensuring these barriers are fit-for-purpose, the Step Change in Safety Major Accident Hazard Understanding workgroup has developed a suite of educational resources for members to use.


Contact Workgroup

To contact the Major Accident Hazard Understanding workgroup, e-mail

Barriers in place to keep us from harm

Barriers can be classified as either plant, processes or people. They must work independently to stop the event from occurring or escalating. However, when there are multiple barriers, they can work together to provide layers of protection.

There are different ways of demonstrating how barriers work together to manage Major Accident Hazard risks and the bowtie model is one common and effective way. The bowtie model shows the threats on the left-hand side and the consequences on the right-hand side, with the incident being the knot in the middle. Barriers placed on the left hand side prevent the incident occurring and the barriers on the right-hand side mitigate the consequences if an incident were to happen.

The bowtie below shows some barriers that could prevent or mitigate against a major accident. (Note some barriers could sit on either or both sides)

Click on each barrier on the bowtie image to access information and resources