Counter-Errorism in Diving: Applying Human Factors to Diving

Gareth Lock at The Human Diver
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Nov 8, 2025 • 11min

SH224: CCR Diver Goes Hypoxic on Surface – What Causal Reasoning Taught Me About Learning from Events

In this episode, we examine a near-miss incident involving a CCR diver who narrowly avoided a hypoxic event during a liveaboard dive. Using this real-life scenario, we explore the importance of understanding human factors and causal reasoning in diving, focusing on how fatigue, stress, environmental distractions, and system design can shape performance and decision-making. We discuss the dangers of hindsight bias, the need to learn from "work-as-done" rather than idealized procedures, and how moving beyond blame helps identify systemic issues to improve safety and resilience. Tune in to discover how these lessons can help you dive safer and smarter.   Original blog: https://www.thehumandiver.com/blog/ccr-diver-goes-hypoxic-on-the-surface   Links: “If Only…” documentary: https://www.thehumandiver.com/ifonly HFiD: Essentials class: https://www.thehumandiver.com/essentials-2025 HFiD: Masterclass: https://www.thehumandiver.com/masterclass-2025 More about the WITH model: https://www.thehumandiver.com/blog/don-t-just-focus-on-the-errors Dirty Dozen Pre-Splash Checklist: https://thedirtydozenexpeditions.com/s/THD_DD-Splash-Checklist-40.pdf Work as done vs work as imagined: https://youtu.be/vtgIwHrUWVQ?si=nKE--HgZPzMaJV7C Diving Talks; Heroes and Villains in Diving: https://youtu.be/gXUhFLK2j3M Video about the Linnea Mills case: https://youtu.be/3b1Mm8zXUow Sign up for LFUO courses here: https://www.thehumandiver.com/lfuo   Tags:  English, CCR, Gareth Lock, Incident Analysis, Just Culture
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Nov 5, 2025 • 4min

SH223: The Effect of your Environment on your Decision Making: Performance Shaping Factors in Diving

In this episode, we dive into the impact of human factors on decision-making in diving, focusing on how environmental elements like fatigue and cold temperatures can shape performance. We explore how jet lag from travel affects cognitive ability and the strategies to mitigate its effects, as well as how cold water impacts dexterity, buoyancy, and mental processing. With insights into the physiological and mental challenges these conditions create, we discuss practical steps to reduce their impact and emphasize the importance of awareness in making better, safer decisions underwater. Original blog: https://www.thehumandiver.com/blog/the-effect-of-your-environment-on-your-decision-making-performance-shaping-factors-in-diving   Links: Diver performance and the effects of cold: https://journals.sagepub.com/doi/10.1177/001872086801000501   Tags:  English, Guy Shockey, Performance Shaping Factors
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Nov 1, 2025 • 12min

SH222: You can’t risk assess a hazard you don’t know about: DeltaP

In this episode, we explore the critical role of understanding hazards in diving and the importance of effective risk management. From the everyday threat of drowning to the more abstract risks like decompression sickness, we discuss how divers rely on equipment, training, and planning to mitigate dangers. The conversation highlights overlooked hazards like differential pressure (DeltaP), which can be deadly when misunderstood, as illustrated by tragic real-world examples. We also examine the psychology of risk normalization, emphasizing that ignorance of hazards can lead to complacency and tragedy. By raising awareness and promoting informed decision-making, this episode underscores the necessity of knowledge, preparation, and humility in diving safety. Original blog: https://www.thehumandiver.com/blog/you-can-t-risk-assess-a-hazard-you-don-t-know-about-deltap   Links: Risk or Uncertainty blog: https://www.thehumandiver.com/blog/risk-or-uncertainty Ignaz Semmelweis: https://en.wikipedia.org/wiki/Ignaz_Semmelweis Video of a toy diver experiencing Delta P: https://youtu.be/uI0WOdX7cfU?t=350 Video of diver clearing lock gate: https://www.youtube.com/watch?v=MWGFEZ1tpsg Incompetent and Unaware presentation: https://youtu.be/pGBYj1BNhvI?si=fioKreIdIS_5nX1F Follow up video to lock gate clearance: https://youtu.be/nKp8duCNvyQ?si=-8jAyHQVGWTP8Ov7 Normalisation of risk blog: https://www.thehumandiver.com/blog/normalisation-of-deviance-not-about-rule-breaking Differential pressure hazards in diving - Diving Information Sheet No. 13Delta P ADCI Checklist Tags:  English, Decision-Making, Gareth Lock, Risk, Risk Management
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Oct 29, 2025 • 6min

SH221: The First Human Factors in Diving Liveaboard- Living our values

In this episode, we explore how a liveaboard trip in Indonesia integrated Human Factors training to transform the diving experience. Jenny Lord from The Human Diver, Brent Webb from Scuba Adventures in Texas and Mark from Master Liveaboards collaborated to create a unique environment focused on psychological safety, teamwork, and debriefing. Over a week, 19 divers, with varying levels of Human Factors training, participated in engaging talks on topics like decision-making, situation awareness, and leadership, alongside dive debriefs that fostered shared understanding and growth. The trip highlighted the power of open communication, self-reflection, and learning from mistakes, leaving participants inspired to bring these skills to their own diving practices and beyond. Original blog: https://www.thehumandiver.com/blog/the-first-human-factors-in-diving-liveaboard   Tags:  English, Communication, Debrief, Jenny Lord, Learning, Psychological Safety
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Oct 25, 2025 • 10min

SH220: I thought: "WTF did you just say?" I actually said: ....nothing. How to say when it’s not okay

Speaking up when something feels off—whether on the dive boat, in a briefing, or underwater—is key to building a safe and inclusive dive culture. In this episode, we explore how small interventions, from a simple pause to a well-placed question, can shift group dynamics and reinforce psychological safety. Using real-world diving scenarios, research-backed strategies, and insights from human factors, we discuss how to challenge problematic comments without escalating conflict. Tune in to learn how small moments can shape dive team culture and why speaking up, even subtly, can make a big difference. Original blog: https://www.thehumandiver.com/blog/wtf-did-you-just-say-i-said-nothing   Links: Reel from Kenny Dyal and Sweetwater Scuba: https://www.facebook.com/reel/1385836736105494 Blog from Nic Emery: https://www.thehumandiver.com/blog/what-are-we-pretending-not-to-know Psychological safety blogs from THD: https://www.thehumandiver.com/blog?tag=psychological+safety “How to say when it’s not ok” paper: https://www.lboro.ac.uk/media/media/campaigns/iwd/how-to-say-when-its-not-okay.pdf THD wetnotes: https://the-human-diver.myshopify.com/collections/frontpage/products/thd-wetnotes-divers-notebook Asch conformity experiments: https://www.youtube.com/watch?v=tEhABrJ4T2Y   Tags:  English, Communications, Gareth Lock, Leadership, Psychological Safety, Teamwork
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Oct 22, 2025 • 5min

SH219: Why are dive briefings important? How to deliver them effectively

Effective dive briefings are key to safe and successful dives, yet many divers overlook their importance. In this episode, we explore how structured briefings help build a shared mental model, reducing misunderstandings and improving team coordination. Using the UNITED-C framework—covering goals, roles, risks, contingencies, and more—we break down how to deliver clear, effective dive briefings that set your team up for success. Tune in to learn how small changes in briefing style can enhance safety, teamwork, and overall dive experience. Original blog: https://www.thehumandiver.com/blog/Why%20are%20dive%20briefings%20important%3F%20How%20to%20deliver%20them%20effectively   Links: Get The Human Diver wetnotes here: https://the-human-diver.myshopify.com/collections/frontpage/products/thd-wetnotes-divers-notebook   Tags:  English, Brief, Mike Mason, Team, Teamwork
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Oct 18, 2025 • 6min

SH218: Being Understood, not just Transmitting

Show Notes Summary: In this episode, we dive into the challenges of effective communication, especially in multicultural and high-stakes environments like diving. Using a real-life example from a Human Factors in Diving class, we discuss how cultural misunderstandings and non-verbal cues can lead to confusion and unintended consequences. We explore the importance of tailoring messages to your audience, breaking communication into manageable chunks, and using techniques like pauses, closed-loop communication, and clear written formatting to ensure understanding. Whether on land or underwater, making your message "land well" is key to building shared understanding and effective teamwork. Original blog: https://www.thehumandiver.com/blog/being-understood-not-just-transmitting   Links: Another blog about Situation Awareness: https://www.thehumandiver.com/blog/unleashing-your-sixth-sense   Tags:  English, Communication, Communications, Debrief, Jenny Lord, Situation Awareness, Team
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Oct 15, 2025 • 7min

SH217: Normalization of Deviance (Risk): How Socially Accepted Drift Can Impact Your Diving

Show Notes Summary: In this episode, we explore the concept of normalization of deviance and how it applies to diving. Inspired by a Divemaster's comment about surfacing gas reserves, we discuss how divers can unknowingly drift from safety standards over time, often influenced by social norms or perceived authority. Normalization of deviance, coined by Diane Vaughan, describes how repeated deviations from acceptable standards become normalized when no immediate consequences occur. We contrast this with constructive deviation—deliberate, researched changes to improve safety—and share practical steps to guard against normalization of deviance in diving: establish clear Standard Operating Procedures (SOPs), conduct thorough pre-dive briefs, and hold regular debriefs. Building a culture of psychological safety is essential for divers to feel empowered to question and challenge unsafe practices. Original blog: https://www.thehumandiver.com/blog/normalization-of-deviance-risk-how-socially-accepted-drift-can-impact-your-diving   Links: NOD isn’t about rule breaking blog: https://www.thehumandiver.com/blog/normalisation-of-deviance-not-about-rule-breaking Debrief model” https://www.thehumandiver.com/debrief   Tags:  English, Decision-Making, John Strobridge, Normalisation of Deviance, Normalization of Deviance, Risk
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Oct 11, 2025 • 16min

SH216: Diving Deep into Diving Safety: The death of Linnea Mills through a lens of HF and System Safety

Diving is often seen as a safe and relaxing sport, but true safety goes beyond avoiding accidents—it requires building resilience and learning from mistakes. In this episode, we explore how incidents often stem from systemic pressures and "practical drift," not just individual errors. Through real-world examples from diving and other high-risk industries, we highlight the importance of open debriefs, a just culture, and robust training to prepare divers for real-world challenges. By embracing transparency and focusing on system-level improvements, we can create a safer, more adaptive diving community that prioritizes learning and continuous improvement. Original blog: https://www.thehumandiver.com/blog/linnea-mills-death-hf-systems-lens   Links: “Bad Apples”: https://www.thehumandiver.com/blog/from_blaming_to_learning Just a Routine Operation video: https://www.youtube.com/watch?v=JzlvgtPIof4 Court submission for Linnea Mills death: https://www.scribd.com/document/555406095/Mills-v-Gull-Dive-Center-PADI-2nd-Amended-Complaint History as a cause: https://www.montana.edu/rmaher/engr125/CAIB-History%20as%20a%20cause.pdf Restorative Just Culture checklist: https://safetydifferently.com/restorative-just-culture-checklist/ Laura Walton’s Fit to Dive: https://www.fittodive.org/ Diving incidents often remain hidden: https://www.youtube.com/watch?v=DRXqeQvRFK0 Sidney Dekker’s tunnel: https://www.thehumandiver.com/blog/its-obvious-why-it-happened Research about sharing stories in diving: https://www.youtube.com/watch?v=DRXqeQvRFK0 Blogs on THD about psychological safety: https://www.thehumandiver.com/blog?tag=psychological+safety Blogs on THD about why context matters: https://www.thehumandiver.com/blog/search?q=context+matters Asking questions about local rationality: https://www.thehumandiver.com/blog/learning-reviews-in-diving   Tags:  English, Gareth Lock, Healthcare, Incident Analysis, Just Culture, Normalisation of Deviance, Psychological Safety
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Oct 8, 2025 • 5min

SH215: Situation Awareness and Mental Models: Making it easier to the do the right thing

In this episode, we explore why situational awareness (SA) is the most critical skill for divers, even more so than technical abilities like buoyancy control or propulsion. SA isn’t just about noticing and processing information—it’s about projecting it into the future to anticipate outcomes. Through real-world examples, we highlight how building mental models—scripts based on experience and “what if” thinking—helps divers make quicker, better decisions in complex scenarios. We also discuss the vital role of structured debriefs in turning experiences into actionable insights, ultimately creating divers who can handle challenges with confidence and skill. Original blog: https://www.thehumandiver.com/blog/situation-awareness-and-mental-models-making-it-easier-to-the-do-the-right-thing   Links: Further reading from The Human Diver blog: Selective Attention Exists! 5 Tips to Increase Situational Awareness in Diving Unleashing Your Sixth Sense: Building capacity and directing attention Running out of gas- Why does this happen and how can we prevent it? How do I improve my Situation Awareness? You can't pay MORE attention: the myth of 'loss of situation awareness'   Tags:  English, Debrief, Guy Shockey, Situation Awareness

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