Flying after diving… what are the guidelines?

Here’s a somewhat common scenario… perhaps one you have experienced yourself; or thought about at least.

Anyhow, here it is. You and your buddy are on a dive vacation someplace that requires airline travel… bummer, right!? Pack light. Hope the TSA doesn’t break anything on your way out. Hope customs at the destination doesn’t fuss over anything on the way in.

However, all those issues aside, every other piece of the planning puzzle is falling into place just fine except for one small issue. The flight home is scheduled wheels-up at O-Dark-Hundred in the morning, and there is an opportunity to dive something really, really cool the previous afternoon… late in the afternoon. The question is: Can you do that dive without getting bent like a pretzel on the flight home less than 12 hours later?

The whole issue of Pre-flight Surface Interval (PFSI) is a contentious one. The old-school guidelines were wait 24 hours after diving before jumping on a commercial flight. But that recommendation has been revisited in more recent studies and the PFSI shortened; with suggestions that various other factors such as breathing nitrox, the length of safety stops, gas breathed during safety stops, and the duration and depth of dive, can all influence by just how much the PFSI can be shortened.

A quick straw-poll of my dive buddies tells me that the definitive answer is a moving target. There is little agreement.

What we can take as read is that flying after diving has a strong potential to apply extra decompression stress on a diver and increases their risks of decompression sickness. There seems to be a direct relationship between the risk dropping and the amount of time spent out of the water increases allowing excess inert gas to be eliminated normally and harmlessly through the lungs. Some trials have estimated the PFSI necessary for a low DCS risk (read acceptable number of incidents of DCS) after relatively long single or repetitive no-decompression dive profiles sits between 11 and 16 hours.

The PFSI for dives requiring staged decompression stops, was around 22 hours. At first blush then, a 24-hour break after diving would seem in most sport-diving cases to be very conservative. But then again, what worked in a dry chamber on a couple of hundred test subjects, may not apply to the average dive tourist coming home from a week in paradise where the diving was punctuated with rum, grilled fish and late-night romps on the beach. Equally, it also may not apply to an informed technical diver who pads her/his decompression stops with extra time, and breathes pure oxygen for long periods during that PFSI!

Well worth the download and reading time is: The Influence of bottom time on preflight surface intervals before flying after diving, published by Undersea Hyperb Med. And authored by Vann RD, Pollock NW, Freiberger JJ, Natoli MJ, DeNoble PJ, Pieper CF. (2007). It is available from the ultimate diver’s research tool: http://archive.rubicon-foundation.org/xmlui/handle/123456789/7343.

The study’s conclusion suggests “that bottom time, repetitive diving, and a decompression stop may significantly influence the pre-flight surface intervals required for low DCS risk. Moreover, it highlighted the need for additional human trials to resolve the effects of exercise and immersion on DCS risk during flying after diving. Such information might assist in the calibration of dry, resting trials for the effects of immersion and exercise which would be useful as dry, resting trials are less expensive and faster to conduct because more subjects can be exposed per chamber dive. This might be of aid for improving the accuracy of existing flying after diving guidelines.”

Significant in that conclusion is the call for additional human trials to resolve the effects of exercise and immersion on DCS risk when flying after diving.

I volunteer.

However, I would be far from an average test subject since something seems to put me outside the bell-curve for DCS risk. For example, my experience with PFSI is far from what’s generally acceptable and my practices at times have been foolhardy. Furthermore, I fall outside the age category that most studies could ethically accept in any trial… but all that aside, I would love to be a guinea pig.

 

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The final word from my new book…

This has been a poor year for diver deaths. I have just wrapped up a book called Staying Alive and it’s about risk management for divers… I started it because of a couple of regrettable incidents and as I finished it three months later, more deaths. The book is scheduled for launch next month from Amazon and CreateSpace. Here are my closing remarks.
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IN CLOSING
Perception of risk changes over time. The more successful we are at beating the odds, the less risky we take our behavior to be; and of course, the opposite may be true. Too often, luck reinforces bad decisions and dilutes fear, and fear is surely part of the apparatus, our personal filter, for risk management. We each must understand that because someone surfaces from a dive with a smile on their face, it does not mean they follow a good risk management process or that their behavior is not risky. It is impossible to measure a negative. Vigilance is required.

I am sitting in my office wrapping up this project. There is snow on the ground outside and I will soon have to pack and get ready to fly to Europe and go to yet another interesting and very big dive show. Perhaps I should feel happy, but I do not: I am sad.

Yesterday evening I got news that a father and son (a boy of 15 who had earned no level of scuba certification at all) had both drowned in the Eagles Nest Cave, an advanced-level North Florida system considered a challenge to certified and experienced trimix cave divers. They were, according to family, testing out new gear the kid had been given for Christmas. What on earth were they thinking: what was the father thinking as he died? Last week, two more technical divers perished. One in the Red Sea and one in the caves of Mexico. I knew them both. One much better than the other but both were nice guys; both were experienced, and unlike the father/son combination who died in a spot where neither belonged, both of last week’s victims were what one would call careful divers.

Fatal dive accidents frequently have multiple and complex, often interconnected, root causes. While each accident has unique qualities about it – in part because of the individuals involved – most accidents can be characterized as a chain of small events that lead to disaster.
This chain of events very often starts with a minor challenge – a failure in communications, a broken strap – and one event meshes with a deficiency or mistake elsewhere and triggers something even more serious, and this in turn results in escalating calamities until the house of cards has fallen down completely. To stay on top of things, technical divers need to become pretty slick at recognizing problems early, preventing a chain reaction, and thereby avoiding a one-way ride to calamity. Often something as simple as calling a dive early, before anyone gets close to the edge, can change the outcome radically and turn a potentially nasty epiphany into a positive learning experience.

Gareth Lock, who was kind enough to write the foreword for this book, is a Royal Air Force officer with a background in risk analysis and management. In his writings and presentations, he shares with us a refreshingly analytical view of dive accidents.

He and I arrive at a similar destination via quite different analytical pathways. Based on his background in the military, he uses what he calls the HFACS Dive model (pronounced H – FACS-D). His analysis and methods are based on the Human Factors Analysis and Classification System framework developed by Dr. Douglas Wiegmann and Dr. Scott Shappell of the United States Navy to identify why accidents happen and how to reduce their impact and frequency. Gareth suggests that for a dive accident to occur, several contributing factors have to align. These factors may include organizational influence, unsafe supervision, a pre-condition for unsafe acts, and unsafe acts themselves.

I believe the factors, the triggers, that lead to deaths like the recent ones in a Florida cave, the Red Sea, and Mexico are more personal, more within our grasp. The eight triggers identified back in the 1990s: Attitude, Knowledge, Training, Gas Supply, Gas Toxicity, Exposure, Equipment and Operations, provide divers with a laundry list of potential dangers.

Gareth points out with some clarity, that people ‘get away’ with diving ‘successfully’ when there are errors at every level in his HFACS model: they simply did not align that day. “And that,” he tells us. “Reinforces bad decisions and creates diver complacency.”

One has to agree with him regardless of how or why you feel divers are dying so frequently. It seems that ignoring just one of the eight risk triggers may be enough to begin a series of events that end in death: it may take two or three, and a lucky diver may get away with ignoring four or five without an incident. Life is not fair that way.

Finally, Gareth reminds us: “It is easy to blame a person, when the system is actually at fault.”
I believe too that we are sometimes too quick to blame the individual and often do not trace the mistakes made back to their “systemic” roots, but sometimes all the fault does rest with one person. The system did its best and the best is all we can expect of anything outside of a nanny state. In some instances, the buck comes to a full stop up against the victim’s attitude, their ignorance, their lack of training, their history of flaunting the rules, their willingness to gamble with the odds.

Every day you and I, indeed the whole diving community, are faced with a dilemma: error of omission or error of commission. In cases where we know someone is pushing their luck, do we mind our own business, remain quiet and watch as they hurt themselves or their dive buddies; or do we speak out? If we are part of a system that Gareth and others say needs fixing, do we have the tools to carry out the repairs? Do we even know what to fix and where to start? Can we make a difference?

There’s a kid throwing starfish back into the sea as the tide recedes. A guy walks up and asks him what he’s up to. “Saving lives,” he explains. “The tide is going out and these starfish will die on the beach, so I’m throwing them back in.” The man laughs and tells the kid that the beach is miles long and that there are hundreds, probably thousands of stranded starfish. He tells the kid he can’t save them all. The kid stops what he’s doing, looks at the guy, looks up at the sky, and back out at the ocean. He bends down, picks up another starfish and throws it as far out to sea as he can. “Saved that one!”

My hope is that through all this effort, I may just get one person to think twice before starting a dive with a faulty oxygen cell, or breathing a gas that hasn’t been analyzed, or dismissing a buddy’s suggestion that today is not a good day to go diving or taking an unqualified diver to a trimix depth cave to test new gear. Help me save a starfish.

Some thoughts about cave training…

First off, I need to declare a bit of a conflict here: Since I am a tech instructor and more importantly work for a training agency (and we do have cave diving courses on the menu), my take on certain aspects of “diver education” are bound to be biased. But all that taken into account, the primary message goes something like: If you want to dive caves, get trained. Simples, right?

In my opinion, cave diving is the oldest and purest form of technical diving. A whole lifetime ago, when I lived in England, I was a dry caver and heard about a small group of nut-bar pioneers who were making pushes through sumps in the Mendip Hills on scuba. At about the same time in the USA, a similarly labeled group of local lads where exploring the network of caves that honeycomb Florida’s North-western quadrant from Tallahassee in the north, south to Hernando County. These folks wrote the rules for extreme diving and 30 years later many of the techniques and kit modifications that they learned by trial and error, have become the gold standard for tech divers around the world.

One of the early gifts from cave diving to the rest of the tech diving community is accident analysis and specifically a shortlist of things to help keep divers safe.

  1. Seek proper (appropriate) training
  2. Maintain a continuous guideline to the surface (safety)
  3. Work within proper gas management guidelines
  4. Observe depth limitations
  5. Use appropriate, well-maintained kit

Over the years, those five points, whose authorship is attributed to the late explorer Sheck Exley, have been refined and developed to take changing attitudes and different environments into account.

Regardless, these guidelines remain a pretty good first step in the process of risk management, and they form the basic structure for building a modern technical diving course.

In case anyone is interested and for the record, the current interpretation of Risk Management is the identification, classification, avoidance and mitigation of risk with regards: Attitude, Knowledge, Training, Gas Supply, Gas Mix, Exposure (the combination of Decompression and Depth), Equipment, and Operations. These are expanded a little from that original list but certainly owe a lot to it.

Anyway, in North America, the oldest technical agencies are the two originally formed to teach cave diving to local divers. The NSS-CDS (National Speleological Society Cave Diving Section) and the NACD (National Association for Cave Diving) have been offering structured overhead courses to punters for over a generation. They are both based in North Florida. They both have instructors operating in Mexico (another hot-spot for cave diving), and the Caribbean, and so by default essentially focus operations on North America. The global situation involves some other agencies such as IANTD, NAUI, TDI, CMAS et al. And today, cave training is available through lots of channels.

Bottom line, there is no excuse NOT to take training if you are interested in diving caves.

There seems to be a sort of consensus among the major agencies and the process of earning a full cave diving certification takes about eight days and is broken into three or four steps: Cavern, Intro, Apprentice, Full. There are “post grad” programs that teach more advanced techniques like scootering and diving with stage bottles, sidemount diving and so on but the vast majority of certifications fall into those first four categories.

Actual standards and outlines vary a bit from agency to agency but the outline from NSS-CDS runs like this:

Cavern Diver As originally conceived, the Cavern Diver course was a recreational diving course, taught to recreational divers using basic recreational diving equipment. It was assumed most participants had little interest in penetrating caves beyond sight of the entrance. Today the need for that sort of a program has diminished. With readily available cavern diving sites in north Florida, such as Ginnie Spring and Blue Grotto, and the system of guided cenote tours in Mexico, recreational divers don’t necessarily need to take a complete, two-day course in order to enjoy a safe cavern experience. What is more common now is to use the Cavern Diver program as the first step in the complete eight-day Cave Diver curriculum.

It is where we introduce students to basic cave diving skills, such as equipment configuration, guideline and reel use, and specialized buoyancy control, body position and propulsion techniques. It is also a way to screen students to make sure they possess the necessary abilities before allowing them in the fragile cave environment.

Basic / Intro Cave Diver This is where students begin making actual cave dives — under some fairly strict limitations. By limiting penetration gas to roughly 40 cubic feet, avoiding decompression and prohibiting any sort of jumps, gaps or complex navigation, we allow students to focus on things like basic dive planning, communication and emergency skills. Students who want to gain limited cave diving experience on their own, at the completion of this program, may do so — provided they understand that the cave community will be keeping them on a fairly short leash.

Apprentice Cave Diver By the time students complete the Apprentice level, we will have covered most or all of the academic knowledge and emergency skills required for full Cave Diver certification. Students may receive a limited introduction to decompression diving procedures, as they pertain to cave diving, and will make some simple explorations off the main line. It is at this point that students are ready to gain some more realistic cave diving experience on their own, if desired. Nevertheless, they are expected to keep all dives well within the limitations of their overall experience.

(Full) Cave Diver The final step in the process, the focus here is on gaining additional practice of all fundamental and emergency skills, under more challenging conditions. Students are expected to demonstrate their readiness to be full-fledged members of the cave diving community.

Although a total of 16 training dives is required to reach this point, it is not unusual for students to have made many more practice dives on their own before full Cave Diver certification.” One of the first questions most divers have about cave training is what will I get out of it?”

ANY technical training is designed to challenge participants and to show them exactly where the borders of their comfort zone are. This is very true of a cavern or cave course. Other side-effects would be greatly improved basic skills; for example, progress in a diver’s mastery of buoyancy and trim, situational awareness and emotional control are big indicators for an instructor that someone is “getting it.”

AND of course, a cavern/cave class will take you to places that “normal” folks just don’t get to.

The next pieces of the puzzle of course are to decide where to take training and with whom.

Where is easy: Train where you are going to do the majority of your diving. Cave diving in the Yucatan is a whole order of magnitude different to cave diving in Ontario or Wisconsin. France is different to Brazil. North Florida is not the same as Australia. They all have their moments.

If asked, the default location that gets my thumbs-up is always North Florida. There are a couple of reasons. First would be the variety of caves. There are little tiny ones that you have to crawl through pushing tanks ahead of you; and there are huge passages that could swallow a hockey arena (whoops, Canadian reference. Sorry).

The second reason to train in North Florida is the quality of instruction. There used to be about three cave instructors I’d recommend but that list has grown to about 30. Some are Brits who fly in just to teach a class; one is Italian; one German; most are Yanks and Canadian; and a couple are even real Floridians.

One thing that is a constant challenge is weeding out the wanna-be instructors from the real thing. Rather than publishing a list of names and forgetting someone, here are eight questions you can ask.

1. How long have you been cave diving and how many cave dives do you make for yourself outside of the training programs you teach?

2. Do you teach full-time or part-time?

3. What other programs do you teach besides cavern and cave?

4. What kit configuration do you use and teach your students to use and why?

5. Can you give me a typical course schedule including dive sites and dive profiles

6. What specific changes do you look for in students before you sign off on their certs?

7. How many students did you fail last month, and how many did you pass?

8. What should be my primary take away from your course?

Cave diving is what I do for fun and relaxation with a handful of special mates, when I want to get away from the dive industry. Ironic maybe but cave diving feels more comfortable and secure than any other type of diving… which is probably why I have managed to resist the temptation to teach it!

When someone asks which cave I like the best, there’s really no answer. I like them all. There are certainly some that I will go out of my way to dive.

When I got word that the Eagles Nest — a deep and massive cave system off in the woods near Florida’s Gulf Coast — was being shut down for an indefinite period about 12 or 13 years ago, I literally left a birthday party early (mine) drove to the airport in Toronto and flew down to Gainesville and a mate waiting for me with a set of twins pumped full of trimix and three decompression cylinders. Next evening, I flew home. The Nest reopened years ago and I occasionally go back, but of the deep caves in that area, strange to say, it is not my favorite. Diepolder II gets that vote.

The entrance to # II is a small pond in the middle of a Boy Scouts of America Sand Hill camp ground just off Highway 50. At the bottom of the pond and its pale blue water is a fissure in the limestone that is wide enough for a diver in back-mounted twins to drop down (head-first) starting at about 15 metres to around 55. At the bottom, the cave opens up into a gallery which on the downstream side is about 40 metres from floor to ceiling with depths of 100 metres or more. Really a very cool dive.

Jackson Blue is another real favorite.

Its entrance is directly below a diving board at the business end of Merritt’s Mill Pond in Jackson Blue Springs Park, which is a few kilometers from Marianna up near the Florida / Alabama border. Yep, really the entrance is directly under the concrete platform that houses the dive board.

This cave is not deep — the deepest part of the main passage is about 30 metres — but it is long — about 3 kilometers at last count — and has plenty of little nooks and crannies to explore. JB is probably best known as a scooter cave. Lots of visitors fly through the first five to six hundred metres with the throttle wide open.

That first section of the cave features a passage that is wide, smooth and straight; perfect for flying in formation and a great spot to practice handling a scooter. The next section — probably from the Hall of the Mountain King on to the Banana Room or Stratosphere — seems to have the major pulling power to bring divers to this cave; however, last November a buddy and I spent a total of about seven hours on CCR playing around in the first couple hundred metres of the cave and had an absolute blast. I guess the object lesson is not to overlook the familiar when rating caves. On that score, JB is a real winner.

Florida’s caves are not decorated with Speleothems — no pretty flow-stones or drapery, no soda-straws, stalactites or stalagmites. To see these, one needs to venture a little south east to the Caribbean or west to Mexico’s Yucatan Peninsula or a long way south to Brazil.

The easiest decorated caves to get to, at least from my home a little north of Toronto, are in the Bahamas, and if pressed, this might be the one spot I would choose to go to for excellent cave diving year round above all others.

If you are making a list, Abaco Blue Hole, Dan’s Cave and Owls Hole are places I would like to get back to, tomorrow if possible. Send money to…

OK, so those are a few of my favorites, how about yours?