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Incident Report: Denial Isn’t Just a River in Egypt

As counter-errorism expert Gareth Lock, principal of Human in The System, explains: the river of denial runs deep through the diving community as demonstrated by this actual DCS incident. His report may help you find safe passage.

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By Gareth Lock

A pair of divers was completing their final dive following a week of 60-70 m/197-230 ft trimix diving off Malta in the Mediterranean Sea. The week had been brilliant. Blue skies, calm seas, and some amazing wrecks from the World War II era. This final dive was to be on the Italian fast patrol/torpedo boat Schnellboot S-31. It lays at 63 m/207 ft, almost intact and upright but broken in the middle, looking like someone had partially snapped it, like a stick.

They were planning on a 30-minute bottom time on open circuit using trimix 15/55, and nitrox 50% and 100% breathing gases. The dive itself was uneventful with some brilliant opportunities for photos in the clear water, and the decompression was completed as planned.

The interesting part started when one of the divers got back on the boat. As he took off his twinset, he noticed some disturbances in his vision. He had never had a migraine before, but it appears. in hindsight, to have been the same as the aura that those who suffer from migraines get. Even though the disturbances were obvious, the diver didn’t say anything to his buddy or others on the boat because they didn’t perceive any neurological or musculoskeletal signs or symptoms. After 20 minutes or so, while they were on their way back to the quayside, the visual disturbances cleared.

Approximately 30 minutes after surfacing, the boat arrived back at the quayside and the divers started to unload their equipment. There were multiple twinsets and stages to lift from the boat to the quayside and from the quayside onto the back of the flatbed trucks.

As the diver lifted the final twinset up onto the back of the flatbed, he immediately had a large “burst of light,” and his vision was disturbed. The disturbance was like an out-of-focus area moving across his vision, which meant that he couldn’t see clearly, especially in the focal area of vision. In the past, the diver had researched diving medical issues like PFOs and the link to DCS, and that physical exertion can open a patent foramen ovale (PFO) thereby allowing bubbles to cross from the venous side to the arterial side, which can lead to decompression sickness. At this point, the diver said to himself “I have a PFO!” However, he didn’t articulate this to the others in the team, again because there were no other signs/symptoms present. In his mind, he couldn’t detect any signs/symptoms of DCS, so it couldn’t be DCS!

Decompressions above the Schnellboot. Photo courtesy of Gareth Lock.

The diver finished up moving the rest of the lighter equipment onto the flatbed and set off back to the dive center. He was unusually quiet, but no one mentioned anything to this effect. After 30-40 minutes, the visual disturbances cleared up. The diver still hadn’t said anything to anyone else at this stage, and there were still no signs or symptoms of DCS.

The following day the diver, his teammate, and the diver’s girlfriend flew back to the UK.

What are your thoughts on what happened? What do you think of the diver who didn’t declare his medical issue? Do your thoughts change if I said that diver was me?!

Most people have a negative thought process about the incident diver. If you fall into that category, you are likely to have one of the strongest biases people exhibit. It’s called a “fundamental attribution error.”

Most people have a negative thought process about the incident diver. If you fall into that category, you are likely to have one of the strongest biases people exhibit. It’s called a “fundamental attribution error.” This error can be summarized as: when a negative behavior is observed in someone else, we blame the individual, but when the same negative behavior is demonstrated by ourselves, then we attribute it to external factors. The Fundamental Attribution Error is one of the greatest barriers to learning when it comes to incidents and accidents because we don’t look at why it made sense for someone to do what they did. Lewin’s equation shows that our behaviour is a function of the person and the environment they are operating in. B=f(p,E). So before you judge, look at why it might have made sense for the person to do what they did. Local rationality is why something can appear irrational to someone on the outside, and yet make sense to the individual “inside”.

So what happened to me and why?

This was the last dive of a week’s great diving. My girlfriend (now wife) was holidaying with me in Malta while Howard (my teammate) and I went trimix diving. Kate doesn’t dive and was happy doing touristy stuff around the island while we dived.

I didn’t say anything to anyone on the quayside because I had a pretty good idea that if I did, I would be in a chamber and that would worry Kate; it would also mean we wouldn’t be flying back home the following day either, and I didn’t want to make a mess of the plans! In hindsight, it could have been a lot worse than it turned out. Irrational in hindsight. Locally rational if you think about what was going on in my head.

Upon my return to the UK, my tech instructor recommended a cardiologist who specializes in PFO treatments. I explained my circumstances to the doctor and told him that the dive had a conservative profile, explaining the gases and stops. He responded that “tech divers are a bunch of (expletive deleted)  guinea pigs,” and upon reflection, I agreed. As a naval diving doctor now involved in commercial dive medicine, he advocates for more control and oversight than is current practice. He does not agree with tech divers taking the risks they do. The only way to confirm that I had a PFO was with a test.

Howard inspecting the Schnellboot. Photo courtesy of Gareth Lock.

Within two weeks, I had a transthoracic echocardiogram (TTE) whereby bubbles and saline were injected into a major vein in my left arm as my heart was imaged with ultrasound. At a specific point I was told to do a Valsalva maneuver to observe if bubbles would cross the heart. No bubbles were seen to cross the area where a PFO would be during any of the three times I complied. However, when I did a massive “sniff” as the bubbles were injected, immediately a shower of bubbles was seen crossing my heart wall through the PFO. Post-test analysis showed that I had an 8 mm x 12 mm PFO. You can see a video of my test here. (See attached video in the email).

Video courtesy of Gareth Lock.

Three months later I was in the operating theatre having the PFO fixed with an Amplatzer device. This is best described as two folded-up umbrellas inserted into the heart; the first is deployed on the inside of the heart, the second on the outside, and then as tension is applied, the two umbrellas close together pulling in the flap and closing the hole. Three months after that, I was back to diving, having been signed off as having no bubbles passing across the PFO. Prior to that event, I had had no signs or symptoms of DCS or anything linked with a PFO despite having completed approximately 400 dives and approximately 15 advanced trimix dives to 60-70 m/197-230 ft.

Summary

Denial is a massive issue in diving incidents, especially when it comes to DCS. I have seen numerous incident reports where the one managing the event is the last person who should be involved in the critical decision-making process! In 1993, Michael Menduno published an excellent article in aquaCORPS #5, BENT, which looked at the stigma associated with DCS. You can find it here.

Because of this stigma, the true prevalence of DCS is not really known and therefore the biases that we use to determine the likelihood of a risk materializing lack the data to inform them. Speaking to experts in the field, the real number of DCS events is likely to be four to eight times the reported level. Consequently, we need to change the attitude toward DCS as Jennifer Hunt’s article in aquaCORPS highlights.

There are numerous biases at play when we examine incidents, accidents, and near-hits. The most powerful of these are hindsight bias (where we “know” it would have happened that way) and the fundamental attribution error. In many cases, it is difficult to resist the effect of these biases, but being aware of them is the first step to improving learning throughout the diving community.

No one gets up in the morning and says “Today is a good day to get bent and not tell anyone anything about it.” We are doing the best we can with the resources we have and the pressures and drivers we are subject to. As Sir Andrew Hidden QC said when discussing the 1988 Clapham Junction train crash in which 35 people were killed and 484 were injured, “There is almost no human action or decision that cannot be made to look flawed and less sensible in the misleading light of hindsight. It is essential that the critic should himself be constantly aware of the fact.”

Like incident reports? Read another. 


Gareth Lock is an OC and CCR technical diver with the personal goal of improving divingsafety and diver performance by enhancing the knowledge, skills, and attitudes towards human factors in diving. Although based in the UK, he runs training and development courses across the globe as well as via his online portal https://www.thehumandiver.com.He is the Director of Risk Management for GUE and has been involved with the organization since 2006 when he completed his Fundamentals class.

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Out of the Depths: The Story of British Mine Diving

If sumps and solo cave diving are, well, a bit too Brit for you, you may want to consider diving into the perfusion of flooded serpentine chert, copper, limestone, silica, slate, and tin mines that honeycomb the length and breadth of the Kingdom. Fortunately, British tekkie and member of UK Mine/Cave Diving (UKMC) in good standing, Jon Glanfield, takes us for a guided tour.

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By Jon Glanfield
Header image courtesy of Alan Ball.

When many think of the UK’s caves, with wet rocks and their penchant for darkness, often the images conjured are of tight, short, silty sumps, that can only be negotiated by intrepid explorers outfitted with diminutive cylinders, skinny harnesses, wetsuits and typically a beard. These are the domain and natural playground of the well-known, highly-respected, Cave Diving Group (CDG). 

In truth, much of our sceptered isle’s caves are of this ilk, but there is an alternative for the diver who favours a more conventional rig, extra room to manoeuvre, and perhaps a more team-orientated approach—one that is less than optimal in many of the true cave diving environments of the UK.

Holme Bank. Photo by Ian France.

Alongside our natural cave diving venues, we also sport a varied collection of flooded mines across the length and breadth of the Kingdom. In the south and southwest, miners have extracted metals such as tin and  copper, while in South Wales it was the mineral, silica. The Midlands Linley Caverns were a source of limestone before being converted to a subterranean munitions store in WWII. Sadly, access to these is no longer feasible. In the rolling hills of the Derbyshire Dales, flinty, hard chert strays close enough to the surface to be mined. In North Wales, the once-proud slate industry has left its Moria and Mithril redolent halls and tunnels beneath the landscape, while copper and slate underlay parts of Cumbria. Meanwhile, just over the border in Scotland, limestone was the resource that drove us to follow its veins into the earth.

Mike Greathead descending the stairway to heaven. Photo by Ian France.

Undeniably, here in the UK, mine diving has a much shorter documented history than that of its close cousin cave diving, but some of the luminaries of this dark world were, and are, active in both. Some of the initial dives in sites like the Cambrian slate mine were undertaken by the incomparable Martyn Farr, Geoff Ballard, and Helen Rider in 2006. But it wasn’t until 2014 that it was further explored and lined by the likes of Cristian Christea, Ian France, Michael Thomas, and Mark Vaughan amongst others. 

Both Rich Stevenson and Mark Ellyatt, who were part of the vanguard of the technical diving revolution in the UK, had personal dramas on trimix dives in the deep shaft of the Coniston Copper Mines, the depth of which runs to 310 m/1012 ft. Ellyatt made his dive at 170 m/555 ft in the early 2000s in a vertical 2 m/6.5 ft square shaft, dropping away into the 6º C/43º F frigid blackness.

Mines Over Matter

As was alluded to, the differences in cave and mine diving are significant. Conventional, redundant open and closed technical rigs can be employed in mine diving due to the predictably larger tunnels, passages, and chambers. Water movement is negligible, so often regular braided lines can be used, lines which would not endure the flow in many of the UK’s upland cave locations. Small teams can dive in safely. 

No Exit. Photo by Chris Elliot.

In general, it is not common to surface and explore the sumped sections of the mines, due to often dangerously contaminated or hypoxic air quality. Also, in some cases, oils and other contaminants have leached into the water. The ever-present risk of collapse—both in the submerged sections and in the dry access adits or portals—haunt divers’ thoughts and is far more common in mines than in the smooth, carved bore of a naturally-formed cave. Casevac (the evacuation of an injured diver) is complex, long-winded, and often dangerous for those involved, and in the event of an issue involving serious decompression illness (DCI), almost certainly helicopter transportation would be necessary given the remote locations.

Landowner access—or, more commonly, denial of access—is an ubiquitous spectre in the underground realm, dry or wet, and much effort is directed at maintaining relations with landowners to safeguard the resources. Some of the most frequented mines are accessible only via traverse of private property, which could be agricultural, arboreal, and in one case, bizarrely on the grounds of an architectural firm. Careful management of these routes into the mines is critical, as is demonstrating respect for the land owner and complying with their requirements when literally on their turf.

At the more prosaic level though, simply getting into some of the mines is a mission on its own, necessitating divers’ decent levels of fitness, the use of hand lines, and sometimes as much consideration of dry weight to gas volume as the dive planning itself. Careful thought and prior preparation are also required in terms of both accident response and post-dive decompression stress, given the exertion expenditure simply to clear the site.

A passageway in Aber Las. Photo by D’Arcy Foley.

Many of the mines are relatively shallow, mostly no more than 30 m/98 ft with exceptions in the notable and notorious Coniston, and the almost mythic levels in Croesor, extending beneath the current 40 m/130 ft galleries that are known and lined. Though, what the mines lack in depth, they make up for in distance and grandeur. 

Aber Las mine survey. Courtesy of UKMC.

Aber Las, or Lost, is more accurately a forgotten section of Cambrian that extends nearly 600 m/1961 ft from dive base at the 6 m/20 ft level, and a second level 300 m/984 ft long at 18 m/59 ft. The section features no less than 35 sculpted chambers hewn off the haulage ways with varying dimensions and exhibiting differing slate removal techniques. Cambrian’s chambers less than a mile away are larger still, and a lost line incident here could be a very bad day given the chambers’ cavernous aspect.

In The Eye of the Beholder

Beauty is—as they say—in the eye of the beholder, but it would be disingenuous to try to draw comparisons between the UK’s mines and the delicacy of the formations in the Mexican Karst, the light effects through the structures in the Bahamian sea caves, or the sinuous power tunnels of Florida. In mines, the compulsion to dive is due in part to the industrial detritus of man, encapsulated in time and water.

In mines, the compulsion to dive is due in part to the industrial detritus of man, encapsulated in time and water.

Parallels are frequently drawn between wreck diving and mine diving, but often the violence invoked at the demise of a vessel—the massive, hydraulic inrush of fluid and the subsequent impact on the seabed—wreaks untold damage and destruction upon its final resting place. In contrast, nature reclaims her heartlands in the mines by stealth: a slow, incremental and inexorable seep of ground water, no longer repulsed by the engines from the ages of men, gradually rising through the levels to find its table. The result is often preserved tableaus of a former heritage with a rich diversity of artefacts left where last they served.

A leftover crate in the Croesor mine. Photo by Alan Ball.

Spades, picks, lanterns, rail infrastructure, boots, slowly decomposing explosive boxes, battery packs, architectural joinery, scratched tally marks, and, even in some cases, the very footprints of the long-past workers in the paste that was cloying, coiling dust clouding the passages and stairways, can be picked out in the beam of a prying LED.

Spades, picks, lanterns, rail infrastructure, boots, slowly decomposing explosive boxes, battery packs, architectural joinery, scratched tally marks, and, even in some cases, the very footprints of the long-past workers in the paste that was cloying, coiling dust clouding the passages and stairways, can be picked out in the beam of a prying LED.

Underpinning, protecting, preserving, and improving these gems of the realm is the UK Mine and Cave Diving Club (UKMC), which formed as mine diving intensified in the mid 2000s. So it was that Will Smith, D’Arcy Foley, Sasha London, Jon Carter, Mark Vaughan, and Ian France, all of whom are respected and experienced cave divers in their own right, forged the club to foster and engage with a community of like-minded divers. 

Sadly, in 2014, Will Smith fell victim to the insidious risks of contaminated air in the Aber Las mine system, which he had been lucky enough to re-discover and in which he conducted early exploratory dives as the club gained traction and direction.

As new members filter into the ranks, new ideas, new agendas, and new skill sets re-shape the club’s direction. At present, we are rebooting the club with a remastered website, focusing on new objectives and seeking opportunities to improve, catalogue, and document the resources we husband.

Lines laid in the Cambrian slate mine. Photo by Mike Greathead.

Exploration continues: the club is laying new line in some areas. What’s more, through our demonstrable respect and care for existing sites, the club is facilitating exploration in previously inaccessible sites, and lost and forgotten sites will resurface. Meanwhile, we’re improving the locations we frequent weekly for the benefit of trainees, recreational (in the technical sense) divers, and survey divers alike. Archaeological projects are rising from the ennui of lockdown; we’re establishing wider links with mine diving communities elsewhere to share techniques, data, and ultimately hospitality.

In Welsh folklore, a white rabbit sighted by miners en route to their shifts was believed to be a harbinger of ill fortune, but for Alice, following the rabbit into its hole led her to a whimsical and magical place. Be like Alice, and come visit the Wunderland!

Additional Resources:


Jon Glanfield was lucky enough to get his first puff of compressed air at the tender age of five, paddling about on a “tiddler tank,” while his dad was taught how to dive properly somewhere else in the swimming pool. A deep-seated passion for the sport has stayed within him since then, despite a sequence of neurological bends in the late 90s, a subsequent diagnosis of a PFO, and a long lay-off to do other life stuff like kids, starting a business, and missing diving. Thankfully, it was nothing that a bit of titanium and a tube couldn’t fix. He faithfully promised his long-suffering wife (who has, at various anti-social times, taken him to and collected him from recompression facilities) that “this time it would be different” and that he was just in it to look at “pretty fishes.” So far, only one fish has (allegedly) been spotted in the mines. The ones Jon has encountered in the North Sea while wreck diving just obscured the more interesting, twisted metal.

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