SH161: ‘One mistake and you are dead’ – isn’t how accidents normally happen

In this episode, we explore the dangers of "normalisation of deviance"—the gradual erosion of safety standards through repeated shortcuts—and its impact on rebreather diving and other high-risk activities. Drawing on lessons from aviation and diving, we discuss how human factors, cognitive biases, and systemic drift contribute to accidents, emphasizing that outcomes should not be the sole focus when analyzing incidents. Using models like the Swiss Cheese Model and concepts of systems thinking, we unpack how multiple, seemingly minor factors can align to create critical incidents. Learn how applying tools like checklists, audits, and effective debriefs can help mitigate these risks and maintain safety margins in diving and beyond.

Original blog: https://www.thehumandiver.com/blog/one-mistake

Links: “If Only” documentary: https://www.thehumandiver.com/ifonly

John Bantin’s Undercurrent article: https://www.undercurrent.org/blog/2020/06/01/the-tragic-and-un-necessary-death-of-brian-bugge/

Debrief model: https://www.thehumandiver.com/debrief

Normalisation of Deviance: https://vimeo.com/174875861

Simple Swiss cheese model: https://vimeo.com/326723142

Big Hole animation: https://vimeo.com/326723122

Little Hole animation: https://vimeo.com/326723109

HSE report: https://www.hse.gov.uk/research/rrpdf/rr871.pdf

Tags:  English. CCR, Complacency, Decision Making, Gareth Lock, Human Factors, Rebreather