Bowtie Technique
The Bowtie Technique is a risk assessment and analysis method that visualizes the relationship between causes, consequences, and barriers (preventative, detective, and recovery measures) around a central hazard or top event, helping organizations understand and communicate how multiple layers of defense can prevent or mitigate disasters.
THE IDEA
Using the Bowtie Technique to Unpick the Key Causes of What Happened
To avoid a disaster at sea, many measures should be (and were) designed and put in place to prevent damage to the Titanic, its passengers and crew. These included:
- Preventative measures – e.g. travelling in a designated shipping lane intended to avoid icepacks, with an experienced crew;
- Detective measures – e.g. lookouts;
- Recovery measures – e.g. bulkheads to compartmentalise any water ingress, water pumps and lifeboats.
Diagram 12.1 sets out, using the Bowtie format, many of the measures or lines of defence in place to maximise the chances of a successful, safe crossing of the Atlantic.
Thus, contrary to some urban myths, the Titanic was designed and built with an eye on safety.36 There were multiple measures put in place to avoid a disaster, and these were signed off by the Board of Trade.37 Yet we know that despite putting multiple measures in place, these were not enough to stop the tragedy.
When to use it
Risk management in project planning to identify and document key controls before a hazard materializes.
Safety analysis in engineering (e.g., chemical plants, aviation) to visualize layers of protection against major accidents.
Incident investigation to systematically analyze why existing barriers failed and what can be improved.
Compliance audits to demonstrate to regulators that multiple lines of defense are in place for critical risks.
FROM THEORY TO EVERYDAY LIFE
In practice
Titanic Disaster Analysis
The Titanic was equipped with multiple safety measures: preventative (designated shipping lanes, experienced crew), detective (lookouts), and recovery (bulkheads, water pumps, lifeboats). Despite these, the disaster occurred because multiple barriers failed or were insufficient. Using the Bowtie Technique, the top event is 'ship strikes iceberg.' Causes include navigation error and failure to spot iceberg in time; consequences include sinking and loss of life. Barriers on the left (threat side) include lookouts and course adjustments; on the right (consequence side) include watertight compartments and lifeboats.
A MOMENT TO REFLECT
Put it to work.
Choose a historical accident or near-miss and identify the preventative, detective, and recovery measures that were in place. How did they fail or succeed?
Using the Bowtie framework, map out a common risk in your own field (e.g., a data breach in IT, a production failure in manufacturing). What barriers exist for each cause and consequence?
Which barriers could fail together because they share a dependency? Separately, which recovery measures might have insufficient capacity, as with the Titanic’s lifeboats?
CONTINUE THE CONVERSATION
Source texts
- Beyond the Five Whys Root Cause Analysis and Systems Thinking (James C. Paterson)