This episode examines a 2012 triple fatality at Cenote Chac Mool in Mexico using a Human Factors approach, showing how accidents are rarely caused by a single mistake but by a combination of small, interacting factors. A guide took two recreational divers beyond safe limits into an overhead cave environment without a continuous guideline, and all three ran out of gas and died. Instead of simply blaming the guide, the analysis explores how things made sense at the time, including authority gradients that stopped the divers from questioning decisions, fatigue from multiple dives, pressure to show something impressive, and increasing task load in a complex environment. Using the PETTEOT framework, the case highlights how people, environment, equipment, organisational culture, and time pressures combined to reduce safety margins until there was no capacity left to recover. The key lesson is that safety depends on understanding these system interactions, building psychological safety so people can speak up, and reinforcing clear rules and preparation to prevent small, “normal” deviations from turning into fatal outcomes.

Original blog: https://www.thehumandiver.com/post/chac-mool-triple-diving-fatality

Links: Full CREER manual: https://creer-mx.com/wp-content/uploads/2024/03/Manual-for-Cenote-Dive-Guides-vs010324.pdf

The Thumb rule: https://www.thehumandiver.com/post/top-tips-for-diving-instructors-psychological-safety-and-the-thumb-rule

Learning from Emergent Outcomes course waiting list: https://www.thehumandiver.com/lfeo

Tags: English| Learning, Incidents & Just Culture