In the world of Human Factors, we have a saying, “failing safely,” which translates into… all humans make mistakes – it’s our job to identify those error/mistake traps and design work to lessen those error opportunities. In Process Safety we used to use the phrase “cascading failures”, which is the opposite of “failing safely.” In a cascading failure scenario, it is the perfect example of Heinrich’s Domino Causation model where the first domino falls, hitting the next domino, and the chain of events continues as there is nothing in place to stop it.
In the recent CSB investigation report, we see this cascading failure in the images taken at the time of ignition to the end of the event:
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Most safety pros are familiar with “fire walls” and how they are a physical barrier to prevent (or at least slow the movement) the spread of fire in an area. But not all “safety barriers” are physical barriers.
The CSB found the following, which allowed this event to escalate/cascade into a much larger consequence: