The accident that killed Parker Turner

[Steve S]

Hi Hobby,
If you can ignore the American perspective it is worth reading,
more than the main accident the one's that made me think were Sheck Exley who when he realised he was going to die tied a heavy guide line around himself so that he would be found, and the guy hoplessly lost in a cave who scratched a final message to his Mother on his tank.

Safe diving,
Steve.

[Mark Chase]

<font color='#000F22'>I have the vast experiance of errr three VERY easy caves to my credit and so far I have been singualaly un impressed. As soon as you get out of the daylight zone it just rock and a few glints of shrimp eyes. I have a sneeking suspision that whilst there are probably some stunning rock formations out there it is a dive diciplin for the diciplins sake.

The risks are SOOOOO great that the planning and exicution of the dive become the end rather than the meens. I can kind of understand that because I like planning my dives and fiddleing with gas and profiles on the computer but it all falls flat for me if I cant plan in a bit for the unexpected. I do like spontinuity on a dive.

I cant think of anything more terifiing than being lost in an underwater cave or traped by a land slide.

They call deco diving an overhead environment but I think thats rubbish. You can call a deco dive at any time and head up knowing that up is an option. OK you might have to stop a couple of times on the way but in the end baring equipment failure or a heart attack you are guarenteed to get up.

I respect the deciplin but I think its the danger that keeps them comming back for more.

But thats just a personal opinion and what the hell do I know

Mark Chase

[malcolm smith]

Hi Mark, I have only done a little cave diving in France and Florida, but they have been the most beautiful dives I have done.
These sites have good vis----usually, and don't have to be deep.
If you get the appropriate training, they can be done very safely with a disciplined mindset.
There's nothing macho about it, they are just very beautiful dives.
Cheers, Malcolm.

[Mark Chase]

<font color='#000F22'>I am sure you are right but I read a whole artical on a deep cave penitration and the the artical just read like a dive plan. We gas switched here we swaped scooters here we tied off here. I read it totaly in awe of the twin insperation diving three scooter rig configeration but failed to read any bits about the joy of the cave it's self. Perhaps the caves I have done are just a bit dull.

Are there any caves in England worth doing? Could I get a guide?

Where were the caves you did in France?

Ile have a crack at it, under controled conditions of course to see if I would change my mind.

Mark Chase

[malcolm smith]

I am afraid I don't know anything from personal experience of UK caves, Scoff, I think I saw his name as a member of this list, is the man for that.
French caves I have enjoyed have been in the Dordogne/Lot area.
There is a guide book published.
Courses are available in France from Martin Robson Eau2, Phil Short may be doing them there also,I think he is linked with Kevin Gurr, I am not sure of this though. Also, Deeplue on the South coast may be able to help.
UK course is done by Martyn Farr of Farrworld who would show you UK techniques, Chris Boardman did an article in Diver mag on a course he did with Martyn recently.
If you are seriously thinking about it, do a course rather than just turn up and jump in------you may not come out!!!!! :-)

Cheers, Malcolm.

[peter k]

For them that don't know what happened to Sheck Exley;

On 6April94, cave diver and explorer Sheck Exley died attempting to reach the bottom of the Zacaton sink hole in northeastern Mexico. This physiological analysis relates the conditions and events of the dive as well as we can reconstruct them, and speculates on possible causes of his death. It is not intended to endorse or glorify record-setting exploration nor to judge it in any way; that stands on its own merits as the prerogative of the explorers. These are the facts of the case as well as we can put them together, plus some speculation.

Exley, 45, died while exploring a sink hole or cenote, at Zacaton, located in northeastern Mexico, not far from Mante, the site of his previous record dives. At a depth of 1080 f/332 m or more, Zacaton may be the deepest water filled pit in the world. Exley was diving with Jim Bowden as part of Bowden's &quot;El Proyecto de Buceo Profundo&quot; project. On the day of the fatal dive, Bowden and Exley dived independently, but at the same time and with similar techniques.

Bowden and Exley descended on separate weighted guidelines 25 to 30 feet apart. Bowden started a few seconds before Exley; the descent was expected to take 10 to 12 minutes. The divers kept track of the line visually. From a decompression and gas management point of view, the more rapid the descent the better, but a rapid descent potentially may exacerbate the effect of High Pressure Nervous Syndrome (HPNS) (See aquaCorps Journal N8, &quot;High pressure nervous Syndrome,&quot; by R.W. Bill Hamilton). Both divers had experienced HPNS symptoms on previous dives and planned to slow their descents to less than about 100 f/min (30 m/min.) at about 680 f/229 m. Air was breathed by both divers to 290 f/92 m at which point Exley pause to &quot;stage&quot; his air cylinder by clipping it to the line at 290 f. Bowden used a small &quot;pony&quot; cylinder carried on his back as his air supply. The divers switched to a &quot;travel&quot; mix, trimix 10.5/50 (10.5% O2, 50% He, bal. N2), for the descent from 290 to 580/89-179 m.

Both Bowden and Exley selected a bottom mix that would produce a tolerable PO2 of less than 2.0 atm and an equivalent narcosis depth (END, the equivalent depth on air) of 274 f/84 m at 970 f/298 m. These levels were accepted by both divers since the exposure to maximum depth would be brief (not that a higher PO2 would minimize the lengthy decompression at the cost of increasing the risk of CNS oxygen toxicity. Technical divers are recommended to run their working POs at less than 1.4 atm. See aquaCorps N7, &quot;Blueprint For Survival Revisited&quot;-ed.). Bowden used trimix 6.4/31 and Exley used trimix 6/29 (mixed by adding helium to air). Both divers used gas from the back mounted bottom mix supply to fill their buoyancy compensators (BCs).

Sheck carried a total of about 369 cf (standard cubic feet) of bottom mix in two large back mounted tanks. He also had two side mounted tanks (aluminum &quot;80s&quot; filled 3600 psi) of trimix 10.5/50. Jim carried 426 cf of trimix 6.4/31 in two back mounted tanks and in one side mounted aluminum &quot;80&quot; tank. A second side mounted &quot;80&quot; tank contained trimix 10.5/50. Tanks filled with specific decompression mixtures had been staged on each individual's descent line during the two days prior to the dive. The extended decompression called for mixes of air, enriched air nitrox, argon-oxygen, and oxygen.

It is difficult to overemphasize the importance of gas management and careful gas planning for a dive of this magnitude. At 30 atmospheres (970 f/298 m) the amount of gas in a normal 72cf scuba tank is reduced to less than 2.5 effective cubic feet-good for 2 or 3 minutes, less if exercising. Bowden and Exley followed a rigorous pattern of breathing, taking slow, deep breaths at a practiced rate in order to optimize the tradeoff between excess gas consumption and hypoventilation-which lead to CO2 buildup. A small change in the breathing pattern, especially in rate, can quickly alter usage calculations.

Bowden checked his gas volume about 874 f/268 m. He had expected to have approximately 1800 psi (pounds per square inches) at this point and had only 1000. He realized the need turn the dive and arrested his descent at the 898 f/276 m mark. On the line during decompression, Bowden observed Exley's unused decompression tanks and correctly assumed that Exley had not survived. The support team realized this 18 minutes into the dive when the trail of bubbles on Sheck's line disappeared. Bowden completed his nine plus hours of decompression, surfaced with shoulder pain, and was treated with oxygen, corticosteriods, and hydration.

The positive analysis does not adequately explain the shortage of gas. In 1993 December, Bowden dove to 776 f/238 m in the same system, confirming his anticipated gas usage, as had previous dives to 722 f/222 m and 489 f/150 m. Sheck&amp;#8217;s gas usage in an earlier dive in Bushmansgat confirmed that his gas management technique was adequate.

Bowden concedes that even a slight elevation in breathing rate, beyond his practiced 5-6 breaths/min., would account for the added gas consumption on this dive. Both divers had planned to slow their descents at 679 f/209 m using their BCs which consumed precious bottom mix. Additionally Exley, who had started the dive with less volume than Bowden, slowed at 291 f/84 m to drop his air tank used in the initial stage of the dive.

the day after the dive, topside team member Kristovich and others returned to recover equipment from both lines. Exley&amp;#8217;s was heavy with his staged steel tanks, and plans were made to raise the entire line with a pulley assist from the surface. Two days later, during this process, Exley&amp;#8217;s body surfaced. The line was wrapped several times around both arms and the valves of his side mounted bottles. Entanglement did not involve the back mounted bottles, valves, mounting plate, or BC. His mask and all other equipment was in place. He did not have a regulator in his mouth. His BC contained gas and the inflator was functional. His wrist mounted dive computer revealed a maximum depth of 879 f/270 m. The gauge of his back mounted tanks read 500 psi, the lowest pressure that would have effectively supply gas to the diver&amp;#8217;s regulator at the bottom depth. One regulator of his two side mounted tanks was unhooked and the pressure was 500 psi. The second tank had 3600 psi and the regulator was stowed. A later analysis of the gases for the oxygen component revealed accuracy in the expected mixes. An autopsy was ordered but nothing reported explained the accident. Three days passed since the death, and that combined with the effects of immediate decompression made a confident postmortem analysis difficult.

What went wrong?

We will never know for sure. Most likely Exley reached a point where he was unable to inflate his BC mechanically with compressed gas and wrapped the line around himself to stabilize himself while sorting things out. His maximum depth was 879 f/270 m. Exley may have ascended 75 feet or more, but that cannot be determined for certain from the recovered line, since it was cut during removal from the water. The manner in which the line was wrapped around his upper body makes it unlikely that the entanglement could have happened by accidentally, even if a convulsion had occurred. Exley&amp;#8217;s experience level makes this unlikely as well.

If we accept this, the main uncertainty is why or how he became so low on gas. It was not like Exley to fail to check his gas supply, but the physiological stress of the rapid compression (HPNS) could have occupied him enough that he was not aware of his situation until it was too late. The equivalent narcotic depth of his mix was approximately 242 f/75 m at a depth of 879 f/270 m, an air depth easily within his comfort level, but also a potential contributor to the probable cascade of problems. The gas density was 14 g/l at this depth, the equivalent of breathing air at 334 f/106 m. Resistance to breathing plus intentional slow breathing undoubtedly resulted in an increased level of CO2, possibly high enough to impair performance.

Exley had used some of his trimix 10.5/50 travel mix for the descent, but would not have consumed gas down to 500 psi on that portion of the dive. The travel mix could have been lost to free flow, but more likely Exley breathed it when the supply of trimix 6/29 was exhausted. This was a &quot;hot&quot; mix at 879 f/270 m, where the PO2 would be 2.9 atm; the equivalent narcosis depth was 423 f/130 m, and the gas density 21 g/l, equivalent to breathing air at 487 f/154 m. It could have been breathed during a quick ascent if everything else were under control. However, with the contributory factors of the neurological hyperactivity buildup, it is possible that central nervous system (CNS) oxygen toxicity caused incapacitation or a convulsion. A phenomenon known as &quot;deep water blackout&quot; has caused many divers under less stress to lose consciousness without convulsing. Its exact physiological course, including the cause, is not known.

In addition, equipment failure cannot be entirely ruled out. A fee flow of the primary regulator at depth would have contributed to a very rapid loss of volume and consequent reduction of vital gas reserves.

Conclusion

The most likely sequence of events was that Exley got behind on his gas management, ran low on bottom gas, and could not control his buoyancy so could not ascend. The cause is not clear, but a combination of factors could include stress of HPNS exacerbated by the narcotic effects of nitrogen and CO2. He stabilized his position by wrapping his descent line around his arms, was forced to switch to his trimix 10.5/50 at a depth of at least 800 f/246 m, and was subsequently incapacitated by the prevailing conditions of HPNS, hyperoxia, exertion, CO2 buildup, and nitrogen narcosis.

The accident could have occurred as a physiological consequence o fan illness, known or unknown, that could lead to death or incapacitation on any day in an individual involved in strenuous activity. Likewise mechanical failure, such as something that could cause unexpectedly fast gas consumption or loss, cannot be ruled out.

Peter

[Scoff]

Sorry, I'm a bit late in on this one... and apologies for the length.

First off, a big thank you to Dave Williamson for posting the Parker Turner article in the first place. I had heard of the incident, but had always assumed it was a roof fall onto the diver. Reading what actually happened left me with a few thoughts &nbsp;'now what if??'. Firstly, it struck me again the benefits of using side-mounted tanks for cave diving. Perhaps Parker Turner might not have had to remove his back-mounted tanks when forcing his way through the squeeze. Similarly I will continue to use a separate weight belt, &nbsp;meaning my buoyancy remains fairly constant even if I do have to remove and replace tanks underwater (as I have had to on odd occasions). &nbsp;

I note Ralphy &amp; Dave Williamson's comments on training, experience, and mindsets, training is fine and dandy, but sadly no amount of training can manage to cover every set of circumstances and conditions you may face underwater. What is probably more important to survival is the diver's ability to be able to cope with unexpected events, and figure out solutions to problems that occur. In the catastrophic situation Bill Gavin &amp; Parket Turner found themselves in, I believe that what they did, they did out of necessity - rather than as a result of training or courage.

On one memorable occasion I failed to notice a gentle curve in the passage while laying line down a slope, and I did not belay the line often enough in the big bit of the passage. On my attempted exit found myself trying to get through a &nbsp;too-low bedding - the classic line trap! I had screwed up (rather than had a tragic misfortune as in Parker Turner's case). Nevertheless, the potential outcome was still the same. In deteriorating visibility (from a couple of metres down to a few centimetres) minutes ticked away and gauges dropped alarmingly as a way out was sought. But one thing was certain, panic would kill you as surely as giving up the ghost. You had no option but to keep thinking, searching, and thinking some more. It was a sobering experience I hope never to repeat. Certainly the next day was spent putting in numerous extra belays in the sump, so we never had that problem again.

The other dreaded situation for me is being lost in a sump. By this I don't necessarily mean losing the line. I mean being on a line, but not being sure it is heading where you intend to go. Your mind plays tricks on you, especially in long, complex and murky sumps (e.g. Keld Head). There is sometimes a niggle in your brain that maybe you passed a belay on the way in without seeing a branch line leading off at the same point (e.g. behind a flake or boulder). So coming back out from a different angle, perhaps you have taken the alternative branch (and not seen the real line...)

So if the passage starts to look unfamiliar on the way out, your mind can have you thinking you are not in the same passage as when you came in, and leave you believing that you are now following a line leading to a dead end, with insufficient gas to get you home. The feeling of relief when you spot something you recognise from the way in - and know you are on the right line after all - is better than off-loading a very full bladder.

Lou - many people have the belief that caves collapse with boring regularity. Fortunately for us, this is not the case. In twenty odd years of caving &amp; well over a thousand trips underground, I can honestly say I have never seen a spontaneous collapse. &nbsp;This is hardly surprising really - a collapse would take seconds, and many caves can be shown to be pre-ice age, so you would have to have extremely bad luck to be there when one happened. Caves are a natural feature, with natural equilibrium and collapses &nbsp;should only take place when some external stimulus exerts an influence So floods, earthquakes, and local quarrying activity may cause a collapse. The size nines of a clumsy potholer could also have the same effect.

In diving terms the most likely disturbance would be physical contact with a passing diver, or bubbles. The latter is particularly relevant when you bear in mind that a boulder's weight underwater is around a third lighter than normal &nbsp;- thanks to the water displacement. So a boulder of 4ft x2ft x2ft will weigh around a ton in air. In water it would weigh perhaps only 650 kgs which could be supported easily by other rocks/ ledges. Surrounding the boulder with air bubbles will instantly increase its weight back to the ton, which could cause a drastic effect...

Of course the same arguments apply to wrecks, but these are man-made rather than natural, with an expected lifespan before total destruction of decades rather than aeons. So in terms of risks of collapse, I would prefer to spend time inside a cave rather than a wreck.

I have been lucky to have found myself in new cave passage on a number of occasions, some in the UK, some abroad. Every cave is different, and I believe a good understanding of cave features is of paramount importance in exploring new stuff. Not only will this give you the insight to know where to look for a way on, but will also help you to recognise and avoid potential hazards. Even then, laying line requires the ultimate in care &amp; concentration. British caves are generally considered to suffer from cold water, poor visibility, and small dimensions, compared to say, those in the Dordogne, Florida, and Mexico. Sadly in the UK, we only have a limited number of caves, so we tend tot push them to a bitter end. Having said that, I know of some equally unpleasant sumps in the Dordogne - with crap vis and poorly laid lines - it's just that these are never visited by those who offer training courses, tourism, etc.

A few years ago I wrote a piece on British cave diving which can be found at: www.cavedivinggroup.org.uk/Essays/Scoff.html
It tries to explain the problems we have here. It also tries to explain that the CDG is basically a set of potholers who have taught themselves to dive so they can visit more cave passage than they otherwise could. Their real interest lies in caves and caving - not diving, hence their philosophy, methods and mentality are so different from open water and tekkie divers, who - I think most would agree - are more interested in visiting a variety of places and situations, and enjoying varied experiences rather than specific environment.

So, finally, in response to Mark - your best bet if you want to dive in a UK sump is to find someone from the CDG who will point you (or take you) to one of the few accessible sites (for those with no caving experience) on a day when it's not rained for two or three weeks. To give you some idea of the sumps in South Wales for example, check out the Welsh Section of the CDG's website which has a sump index &amp; descriptions (sorry, don't know the link but I'm sure a Google search would find it if you are that keen). The other alternative is Martyn Farr who is one of Britain's most experienced cave divers &amp; still very keen and enthusiastic.

Hope this helps.

Cheers

Scoff
Cave Diving Group - Northern Section

[Davey Willo]

Hiya scoff,

Good to hear from one of our own cavers, can you expand on the &quot;classic line trap&quot; story please mate.. it sounds too damn scary but I couldn't quite grasp exactly what happened.. (although I grasped the fact that I wouldn't want it to be me)

Thanks mate
Dave.

[Scoff]

A classic line trap occurs usually in passages with an irregular (non-square/ non round) cross section. It's best pictured by imagining you have cut a piece of cake then laid it on a flat side on a plate. Looking at it from plate level, one side will be nice and high, tapering to nothing at the other side. If you are in a straight passage with this cross section, and you lay line along the high bit there is no problem, as you can follow it back through the high bit to get out.

Now imagine the same cake cross section, but instead of a long, straight passage, imagine it curving in half a circle. Your line will start on the outside circumference. But if you follow the circumference without tying your line along that outside wall, as you head round the curve the line will pull into the centre - and into the tapering 'V'. As you then try to exit, you finish up following the line into the tapering 'V' which is too small to get through.

Of course you can get the same line traps in the vertical plane - such as a passage with a cross section shaped like a lens from the side, or vertical rifts where you drop down a narrow shaft of lens shape but viewed from above (i.e. with it tapering in at each end) then make that an 'S shape' when viewed from in front.

These are the simplest examples. In more complex passages with mulitple arch cross-sections you have to be really, really careful to make sure the line leads through the high bit and not under the low rock arches (such as the infamous 'Dead Man's Handshake' in Keld Head).

Of course finding suitable belays in the right places can be a problem. The walls and floor might be perfectly smooth, there may be no boulders on the floor, nor any thread eyeholes, or you may have all of these with a floor of deep silt. Then you have to resort to artifical belays. But that's another of the CDG's 'black arts'...

I hope everyone can follow this, as describing three-dimensional irregular shapes in words, and the spatial problems that go with it, is tricky. This is where being used to playing about in potholes comes in handy, because you can visualise passage shapes and inter-relationships of horizontal &amp; vertical systems more easily.

In the case I quoted earlier - in Golobarscek, Slovenia back in 1990 - it was the slice of cake scenario, but the plate was tilted at around 20 degrees, and the passage curving gently round the tapered end as it descended. The line should have been tied off say every couple of metres or so, whereas it probably got nearly 20 metres laid out without a belay. As I said - I screwed up, probably with the excitement of being in new stuff. On hitting the restriction on the way out, I spent several minutes trying to find a high enough bit in gathering gloom, when my mate Biffo arrived (having being surveying back up the line a few minutes behind me). He looked surprised to see me, as he would have expected me to have exited. When I indicated he should go have a look, he seemed puzzled. When he re-appeared a few minutes later (now in inches of visibility) we gave each other a deep, meaningful look, then tried to give re-assuring 'okay' signals. Biffo went off for another attempt, while I headed back into the sump, and as far over towards the wall where the bigger section was as the slack line would allow. I had just found a boulder I remembered the line going round the other side of (on the way in) when I felt three tugs on the line - indicating that Biffo had found a way through. If he hadn't, my next option would have been to use my emergency search reel to tie on at the recognised boulder, then follow the wall in the higher section, and hopefully find the way back out to the exit. Another alternative would have been to head a few more metres back into the sump, cut the line there, then use the now slacker line (leading to air) to try to follow the wall in the higher bit.

As it was, I just followed where Biffo had gone and was now holding the line. It was extremely low, and graunched the back of the helmet on the roof and second-stage on the floor, but there was a passable way. You'd have had no chance with back mounts.

As I said before, panic was just not an option. I knew I still had a few minutes of air left, that I was less than 60 ft from air, and I was too young and handsome to croke it. And there were still the search reel and cut line options open to try.  Besides which the missus would have given me hell if I'd drowned missen!

So there you go. One (very much) older and rather wiser cave diver lives and learns.

Makes you wonder why we do it...

Cheers

Scoff
(Cave Diving Group - Northern section)

[Hobby]

Originally Posted by [b

Quote[/b] (Scoff @ Mar. 24 2003,23:14)]It was extremely low, and graunched the back of the helmet on the roof and second-stage on the floor, but there was a passable way. You'd have had no chance with back mounts.

And no doubt there will be somebody somewhere who maintains that there's no place for helmets.....as was once said about sidemounts.Ho hum.
Could you recount for those who don't know how the 'Dead Man's Handshake' got it's title please Scoff,I was in my early caving and diving days when my Old Man told me,it made quite an impact.I could'nt do justice to what happened as my memory and knowledge is lacking.
Hobby.