Block 5 · Human Factors & Stigma
Humans make mistakes — and even if you do everything right, you can still get DCS.
Introduction
DCS — “decompression sickness” — is something you can get after a dive, even if you did everything right.
Sometimes inert gases cause harm inside the body, and we cannot reliably predict the exact individual threshold at which that happens.
But when people talk about DCS, the question often hanging in the air is: What did that person do wrong?
Which profile, which physical state — there must be a reason. And that often isn’t just about a rational explanation,
but about assigning blame.
That’s exactly what makes it so hard to be honest, and exactly why symptoms are so often denied.
And that’s why, as a community, we learn less than we could.
But what does it actually look like: Is diving a dangerous extreme sport — or a pretty normal leisure activity? How does the risk compare to other sports?
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Log in nowWhat makes DCS so “different”?
If you sprain an ankle playing football, trip on a hike, or get hurt while cycling, you treat the injury,
let it heal, and move on. That happens — and it usually doesn’t come with accusations.
You don’t have to explain exactly what you did to “deserve” it.
With DCS, it’s often different. Symptoms can be delayed, unclear, fluctuating — and sometimes you’re not even sure
whether it’s DCS at all. At the same time, DCS emotionally comes with an invisible accusation:
“You must have done something wrong.”
Incident analysis is of course useful. Even if someone gets DCS, you can look at whether the profile was simply very risky
or whether it was generally considered safe. In the vast majority of cases, it’s exactly that: a profile that looks “safe”
still leads to DCS. And that’s something you have to accept — you will never know for sure what caused it.
The search for reasons is human. DCS is mysterious, and we’d like to understand what’s happening — that’s one side.
The other side is defensive thinking: If the person who got hit did something wrong, and I do everything right,
then it can’t happen to me.
This matters not because DCS is always so severe that you have to be terrified of it. Most symptoms are mild
and resolve with a bit of oxygen — or even on their own. Sometimes a chamber treatment is needed, very rarely more than one.
And extremely rarely, lasting damage remains.
So it isn’t the severity that scares people — it’s something else: the stigma attached to it.
You’re “the one who messed up”, you’re marked — no one will dive with you anymore…
Better to say nothing… right?
Talk about DCS
Talking about incidents
Even though DCS is a key topic — and for decompression theory it’s obviously the key topic —
it plays a comparatively smaller role among diving incidents overall.
Much more common are ear problems, slips and falls at exit points, rapid ascents and the problems they cause,
and medical emergencies that happen while diving.
People talk a lot about diving accidents too — usually with the justification that we want to learn from them.
But often, what happens instead is: searching for who’s to blame. And that doesn’t help.
When we talk about incidents and accidents in diving, we should keep two concepts in mind —
because they shape how we talk.
Hindsight bias
“Hindsight bias” happens when you already know the outcome. After an accident — in any field —
everyone suddenly knows why it happened and feels certain it should have been obvious beforehand.
It wasn’t. Knowing what happened changes perception. Because we know something went wrong,
we see “warning signs” that we would otherwise happily ignore.
Just Culture
Just Culture means: we don’t start by looking for someone to blame — we try to understand the system.
We talk about incidents in a way that allows everyone involved to feel safe and willing to describe their perspective in detail.
What were the conditions? What information was available? Which routines, which group dynamics, which stressors?
Why did decisions make sense in the moment they were made?
This doesn’t exclude responsibility — but it prevents learning from being strangled by shame and fear.
The topic is far too big for this course. But as usual, here are a couple of pointers on where to go next.
On Human Factors in Diving, Gareth Lock — author of “Under Pressure” — has created a huge amount of resources and courses.
The Human Diver
If you’re interested in this topic, the introductory course “Essentials” is a genuinely great overview — and packed with ideas on how to look at incidents in a way that actually helps you learn.
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Talk. Give O₂. Share data.
If we want the way divers deal with DCS — and with incidents in general — to change, it’s on us to model different behaviour.
When you yourself don’t feel well: if you notice something after a dive that feels “not normal” — talk about it.
Immediately. Not tomorrow. Not “let’s see”. Not “I don’t want to bother anyone”.
And definitely not “that can’t be it” — even if the profile looked unremarkable, something can still have happened.
And if you notice someone else isn’t doing well: support them. Give oxygen. Offer a drink. Be there.
And get help if needed. What you should not do is start by debating the dive profile or showing off theory.
For all incidents: silence protects no one. At best it protects an image — and at worst it costs time, information, and options. A community becomes safer when it can talk about incidents without tearing people apart. So talk about all the small things that go wrong for everyone sometimes — you can learn from those stories. From accidents, often less.
If you want to help make diving even safer overall, you can contribute on different levels. One option is to share your own data. You can report incidents you were involved in and be confident that DAN handles the data responsibly.