Contract Lifecycle Management
ComplianceAugust 18, 2022

Using bowtie to answer the 3 questions

One of our clients, Uniper, posted about using the bowtie method to answer the '3 questions' and I thought it would be good to refresh where the questions come from and why they work well with the bowtie method.
Are you in control? Answer the three basic questions:

1. Do you understand what can go wrong?
2. Do you know what systems prevent this from happening?
3. Do you have information to assure they are working effectively?


The 'Buncefield incident' occurred on 11 December 2005 at the Hertfordshire Oil Storage Terminal, an oil storage facility located near the M1 motorway by Hemel Hempstead in Hertfordshire, England. The terminal was the fifth largest oil products storage depot in the United Kingdom, with a capacity of about 60,000,000 gallons of fuel. A simple tank overfill event that escalated into catastrophic explosion and fire, causing significant damage to the terminal and surrounding business and residential neighbors.

The UK Health and Safety Executive (HSE) prosecuted the 5 operators of the terminal. At the end of the trial in June 2010, Gordon MacDonald, the then Director of Hazardous Installations Directorate (HID) for HSE, issued a challenge to high hazard industries on behalf of all the United Kingdom Competent Authorities to answer the above mentioned three questions from the boardroom down.

The challenge for high hazard industries

The challenge that HSE gave to the UK High Hazard Industry is applicable across the globe as these questions strip down the complex subject of process safety into a simple concept that is easy to understand. An organization can test itself internally, i.e. can it answer these three questions in a structured and clear way? The challenge is to answer all three questions at the same time. These questions are not limited to thinking about people and the environment but can equally be applied to commercial risk management too.

So, how does bowtie help with the '3 questions'? From the image below we can see the first question 'Understand' is the framework of the bowtie or in the case of an organization many bowties as they run multiple hazards. It defines what troubles us as an organization.

The second question 'Know' is what would we do to prevent these threats or consequences from occurring i.e. Barriers and have we got those barriers in place.

The third and final question 'Assure' must be framed by the first two questions, i.e. we seek assurance data that relates to our barriers, as why would you just measure 'stuff' without understanding what you are measuring actually relates to what you are trying to control! Doing the latter, could give you a very false picture on how you are doing, 'Hey, everything is green!' and then 'Bang!' and the board asks 'Why did that happen to us!?!'.

By answering the '3 questions' you are converting your 'data' into powerful information as we all tend to be data rich but information poor. That information can be used in the decision making process and then begs the following questions…

What are you doing differently?

How have you communicated the risks to your workforce (do they know why they need to do things)? As always, please reach out to discuss bowtie and how they can help you manage risk.

Paul McCulloch
Process Safety & Implementation Consultant - Enablon
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