NEDU | John Clarke Online

Diving Accident Investigation

Diving helmets waiting for accident investigations. Click for a larger image.

Compared to aircraft accident investigations, diving accident investigations are often ad hoc in nature, poorly conceived and poorly funded. Nevertheless, these investigations are just as important for the safety of the diving public as are similar investigations for the flying public. Unfortunately, no national regulations presently address how investigations of diving accidents should be conducted: volunteer investigators have no legal status for extracting information about an accident, and they have no legally binding protection from litigation based on the conduct of their investigation or on its results. That is, no business case can be made for conducting diving accident investigations, in spite of the moral authority for conducting them.

With the conviction that this untenable situation must eventually change, this presentation will describe one approach to diving accident investigations with particular emphasis on rebreathers and will draw some comparisons to aviation accident investigations by the National Transportation Safety Board (NTSB).

Aircraft accident investigations

The "black box" containing data recorded just prior to, and during, a commercial aircraft accident.

Pilots know that if they are involved in a fatal crash, the NTSB will investigate the accident by examining in excruciating detail everything those pilots did for hours, perhaps even days or weeks, leading up to that accident. It will investigate how often they called flight service to check on the weather. The NTSB will go through those pilots’ personal logbooks to check on their currency and proficiency, and it will check Federal Aviation Administration (FAA) records for a history of violations. NTSB investigators will also examine an aircraft’s logbooks to scrutinize its maintenance records. They will play back voice and radar data, and if a data recorder is available, they will analyze its contents.

Then they get personal. The NTSB and its FAA counterparts will talk to mechanics, surviving passengers, and friends to ask questions such as, “What were the aviators’ attitudes toward flying? Were they cavalier? Did they take unnecessary risks, or were they careful and methodical?”

Due to the detailed, scripted nature of NTSB procedures, the investigation may take up to a year to complete.

A few years ago a pilot’s engine failed and he was forced to make a water landing just off a beach. The ditching should have been survivable, but he lost consciousness on impact and sank with the airplane as it settled to the bottom in relatively shallow water. He drowned.

If he had been a diver, that would have been the end of the story. The public judgment would have been, “A diver drowned. He tried to breathe underwater; this is what happens.” But this victim happened to drown inside an airplane. So instead of the medical examiner simply saying that he drowned, the NTSB started its very thorough investigation procedures.

Fortunately, the pilot also had a surviving passenger. From the survivor’s statement, the aircraft’s maintenance records, and the mechanic’s testimony, an ugly story of reckless disregard for the most basic safety rules of flying began to emerge.

Do divers ever show a reckless disregard for basic safety rules? You bet. It’s unfortunate that the pilot died, but the events leading to his death were a useful reminder that the media in which we work and play, high-altitude air and water, are not forgiving. Humans are not designed for flying or diving, and nature only begrudgingly lets us trespass — on its terms.

The U.S. Navy and Coast Guard are chartered to investigate diving accidents. Unfortunately, there is a huge discrepancy in the number of personnel and the amount of funding for aviation accident investigations compared to diving accident investigations. The NTSB has hundreds of personnel and tens of millions in funding available, whereas the entire U.S. Navy has at most a handful of investigators with no investigation-specific funding.

Investigation team requirements

In the best of all worlds, an investigation team should have access to both a manned and an unmanned test facility, access to experts in all diving equipment (scuba, rebreathers, helmets), and the ability to conduct and interpret gas analyses — sometimes from minuscule amounts of remaining gas. At a minimum, such a team needs the ability to download and interpret dive computer/recorder data. Some investigations may require the simulation of UBA-human interactions for “re-enactment” purposes. An investigation team should also have diving medical expertise available to review medical examiner reports for consistency with known or discovered facts regarding the accident. Last, it should have in-depth knowledge of police investigative procedures, particularly of the procedures and documentation for maintaining “chain of custody”.

Do rebreather investigations have a future?

Considering the resources and time-frames required for laboratories such as the Navy Experimental Diving Unit (NEDU) to conduct diving equipment evaluations on a limited set of accident cases, and the unfunded costs associated with those investigations, it is difficult to imagine a resolution to an ever-increasing need for rebreather investigations. Almost certainly, no independent federal agency similar to the NTSB will ever be responsible for investigating diving accidents, simply because diving accidents lack national attention: the public at large is not being placed in jeopardy.

It is also unlikely that diving equipment manufacturers would welcome federal agency oversight and regulations comparable to those engendered by the FAA and NTSB. Diving might become exorbitantly expensive. For instance, if a $5 part available for purchase in an automotive store were to be used in an aircraft, it would become a $50–$500 part because of FAA required documentation that it meets airworthiness standards.

The U.S. Coast Guard initiates diving accident investigations and in some cases conducts hearings into those accidents; however, with its enhanced role in Homeland Security, the Coast Guard is unlikely to welcome any efforts to diversify its mission. The cost/benefit ratio would appear to be too great.

For the future, as Dick Vann of DAN has suggested, the resolution may ultimately depend on rebreather users funding a team of dedicated, professional accident investigators. The cost of conducting worthwhile investigations has yet to be determined, and therefore the amount of funding needed to support it is unknown. I suggest that obtaining those estimates should be a priority as we, rebreather users and the industry, decide the next steps in investigating rebreather accidents.

The above are highlights from this author’s publication of the same name, found in: Vann RD, Mitchell SJ, Denoble PJ, Anthony TG, eds. Technical Diving Conference, Proceedings. Durham, NC: Divers Alert Network; 2009; 394 pages. ISBN# 978-1-930536-53-1.

This book is available for download at no cost as a PDF file from the Divers Alert Network website (http://www.DiversAlertNetwork.org/) or from http://archive.rubicon-foundation.org/8300

Why Deep Saturation Diving Is Like Going to the Moon, and Beyond

This week, as the Space Shuttle is making its last circuits around our planet, I lament what has happened to our space program. Yet, I am reminded of another exploration program that has, like the shuttle and the moon programs, reached incredible milestones only to retreat to a less exotic but still impressive status. That other program is experimental, deep saturation diving.

I have been privileged to conduct human physiological research on several deep saturation dives, one being a record-breaking U.S. Navy dive at the Navy Experimental Diving Unit (NEDU) in 1977 to a pressure equivalent to that found at 1500 feet sea water (fsw), or 460 msw*, and on a 450 msw (1470 fsw) dive at the GUSI diving facility at the GKSS Institute in Geesthacht, Germany in 1990. For perspective, the safe SCUBA diving depth is considered to be 130 fsw, although technical and cave divers often descend deeper, to 300 fsw or so.

Dives in hyperbaric chambers like at GUSI and NEDU are simulated; the divers don’t actually go anywhere. But the effects of the high pressure on the divers’ bodies are just as they would be in the ocean. Of course, even in simulated dives, divers wear Underwater Breathing Apparatus, and descend into water contained within the hyperbaric complex.

In 1979, NEDU again set the U.S. Navy record for deep diving to 1800 fsw (551 msw). At Duke University in 1981, the U.S. record for pressure exposure was set by three saturation divers inside an eight-foot diameter sphere. The internal pressure was 2250 fsw (686 msw). One of those divers went on to become the senior medical officer at NEDU, none the worse for his high pressure exposure.

The French company Comex, of Marseille used an experimental gas mixture of hydrogen-helium-oxygen to reach 675 msw, before being forced back to 650 msw due to physical and physiological problems with the divers. However, like teams attempting the summit of Mount Everest, one diver from the dive team was pressed to a world record of 701 msw (2290 fsw), just squeaking past the U.S. record.

There is a poorly understood physiological barrier called the High Pressure Nervous Syndrome (HPNS) that limits our penetration to ever deeper depths. In spite of the use of increasingly exotic gas mixtures, helium-oxygen in the U.S. Navy, helium-nitrogen-oxygen at Duke University, and hydrogen-helium-oxygen at Comex, all attempts to dive deeper have, to date, been rebuffed.

Just as I had thought as a young man that trips to the moon would be common-place by now, I had also assumed diving to 3000 feet would be routine. But it is not.

In my early research days I was interested in the effects on organisms of very high pressure, 5000 psi, which is equivalent to a depth of over 11,000 feet (3430 meters). We now know those effects can be profound, altering the very structure of cell membranes. Reversing those effects while maintaining high pressure, at great depth, is a daunting scientific task. We don’t yet know how to do it.

What we do know is that reaching 1500 feet can be done without too much difficulty. In the 1980s it became almost routine to dive to 1000 feet at both the Naval Medical Research Institute (Bethesda) and NEDU. Deep saturation diving is a thriving business in the oil fields of the Gulf of Mexico and the North Sea.

Click for a larger image.

But as for the similarity between deep saturation diving and NASA’s moon missions, in the Apollo program it took slightly over three days to get to the moon, and almost an equal time to return. But as the above dive profile shows, it took sixteen days to reach the maximum depth of 1500 fsw, and seventeen days to safely return. Over that period of time astronauts would have whizzed past the moon and been well on their way to Mars. Unlike spacecraft and astronauts, divers must slow their descent to avoid HPNS, and must slow their return to the surface to avoid debilitating and painful decompression sickness. Diving without submarines or armored suits is very much a demanding, physical stress.

Politically, exceeding our current depth limits of approximately 2000 feet is akin to returning to the moon, and going beyond. We could do it, but at what cost? Should we? Will it ever be a national priority?

Maybe not for the United States, but I have a suspicion that other countries, perhaps not as heavily committed to space as we, will find the allure of beating current diving records irresistible. If there are medical or pharmacological interventions developed for getting divers safely and productively down to 3000 feet, then that would be a scientific achievement comparable to sending men to Mars.

*[The feet to meters conversion is slightly different from the feet of sea water to meters of sea water conversion. The latter represents pressure, not depth, and therefore includes a correction factor for the density of sea water.]

My Pathway to Writing – Learning from Max McCoy’s “The Moon Pool”

This is not some random book review. I have a personal investment in Max McCoy’s underwater thriller, and to be honest, Max is a friend and mentor.

As the Scientific Director and Senior Scientist of the Navy Experimental Diving Unit (NEDU), I get some unusual calls from time to time. One of the most memorable was from a novelist, Max McCoy.

Not being an avid reader of Westerns, I had never heard of Max, but he had an interesting question. He wanted to know if our large, high pressure chamber, called the Ocean Simulation Facility, could be used to depressurize a small submarine. He gave me the dimensions of the submarine, and little other information to go on.

The unequivocal answer was yes, it could be done fairly easily. With that affirmation, Max traveled to NEDU. After touring our facilities and meeting with our Commanding Officer, engineers, scientists, and submarine medical officers, he began sketching out a closing chapter of his manuscript, the Moon Pool. NEDU would be prominently featured.

During his visit, over lunch, we talked a little about my non-fiction writing project, a spiritual/supernatural collection of carefully filtered anecdotes. He encouraged me in my efforts, and even shared an amazing story of his own. But what Max did not know was that I was stuck in the style of science writing that had been the mainstay of my scientific career. It was hard writing, and frankly, hard reading as well.

When Max returned to Kansas, he sent me his manuscript, which I devoured. The Moon Pool was a change of pace for Max as well. He had been an avid diver for years, and had a diving related story brewing in his mind for some time. For him, The Moon Pool was a welcome, if temporary, release from the Western genre for which he was so well-known.

When I finished the manuscript I began an almost maniacal writing session of my own — an all nighter — writing how I thought the NEDU chapter should read. Since no one would see it, I featured myself and my buddies, inserting our characters into the story, and with a plausible and action-filled story line. I had never had so much fun writing — the words spilled out of my head onto the keyboard.

I sat on that secret product for probably a week before I told Max what I had done. He asked to see it, and much to my surprise, he and his publisher liked it. Even more to my surprise, my character and those of my friends ended up in the last chapter of Moon Pool, modified of course to meet Max’s needs. That book, published in 2004, has a treasured place in my office at NEDU.

On the back cover is my blurb, “A one-of-a kind underwater thriller. The sinister beauty of the underwater world is painted in hues that only an avid diver and inspired novelist could capture.” On the front cover, my dear friend Bob Barth, the Navy’s first Aquanaut, wrote, “A great book! Compelling stuff.” By the time Max visited us, Bob had authored his own book on the Navy’s historical Sea Lab program.

I owe a great deal to Max, for he taught me just how fun creative writing can be, and how, with proper guidance, it can be turned into a commercial product. I have since written two books, one written in record pace, for me at least. The novel, working title “Children of the Middle Waters” is a mixed military-science fiction story that involves my favorite things, flying and diving, with a pinch of top-secret government intrigue; just another day at NEDU. After a long gestational period, I used the creative writing skills developed in the novel to improve the style of the spiritual/supernatural manuscript. Both Children of the Middle Waters, and the spiritual book have yet to be published. But I’m optimistic that will happen in good time.

I will discuss those works more in upcoming blog posts.

By the way, Max’s Moon Pool begins with a supernatural event that is tantalizing in its originality. Furthermore, my spiritual book contains an anecdote of a supernatural experience Max experienced when young. Finally, as a tribute to Max McCoy, he is the inspiration for an investigative journalist in Children of the Middle Waters.

In retrospect, that was quite an auspicious phone call I took one day eight years ago.

Below are links to Max’s web site and his writer’s blogs.

http://www.maxmccoy.com/

http://www.maxmccoy.blogspot.com/

http://www.signalsandnoise.net

My Top Three Diving Sites: The Great Barrier Reef, Australia

My Navy travels have afforded me the privilege of diving in some of the most interesting places. In this, and the next couple of posts, I list my top three diving destinations.

I’ve been diving on the Australia’s Great Barrier Reef on two occasions, both times departing for the reef from Cairns, pronounced like the first syllable in “Kansas”. The first trip was to the inner reef, a short boat ride away from the docks. That experience was OK, but not what I had expected. It seemed like the reef had been abused by massive diver and snorkler populations which had not treated the reef with the respect it deserved.

On my second trip to Australia on Navy diving business, I traveled with the Commanding Officer of the Navy Experimental Diving Unit, CDR (later CAPT) Jim Wilkins.

Scan20083 — Two NEDU Divers - Jim Wilkins and John Clarke (the short one)

From Cairnes we took a fast boat to a liveabord vessel anchored on the outer reef. It was a beautiful 140 ft. tall schooner, SV Atlantic Clipper. And that made all the difference.

During the diving season the Clipper is stationed on the outer reef, and shuttles divers to four diving locations; Norman Reef, Saxon Reef, Hastings Reef, and Michaela’s Reef. Each location featured different underwater vistas, showing an overwealming diversity of colorful reef animals. On a typical day we’d make three daylight dives of varying depths plus a night dive.

SV Clipper blog shot — SV Atlantic Clipper

After one memorable night dive we walked up the long gangway to the deck, shed, cleaned and stowed our dive gear, and then, attracted by commotion at the bow, found a cluster of divers feeding large fish while six or more Bronze Whaler sharks circled amongst the fish, which seemingly paid the sharks no mind at all. The fish knew where the sharks were at all times, and only the healthiest, quickest fish dared feed in such proximity to the large predator. The agile fish apparently felt confident they could dodge the far more cumbersome sharks, because while we watched, not a sinlge fish was taken.

I, on the other, was not quite so agile. And I admit that it bothered me a bit that while I had been swimming through the dark to a dive ladder on the port side of the vessel, near the stern, Bronze Whalers were circling alongside the port bow. But the ship’s crew assured me that the Bronze Whalers were “not particularly dangerous.” They had attacked spearfisherman and “bathers”, but the attacks had not been fatal.

Well, that’s comforting, I thought.

I have to say the most memorable series of dives were with the magnificent Green sea turtles. To observe such beautiful and docile creatures in their native environment was probably the highlight of the entire trip.

During one of the many dives I learned a valuable lesson about diving with diveboat gear. Through the years I’d been diving, since 1964, the equipment was either my own, or belonged to the Navy, and was always maintained in like-new condition. It may have looked battered, but mechanically it was pristine.

As Jim Wilkins and I descended through 60 feet on one dive, I noticed my regulator was becoming increasingly difficult to breathe. I checked my bottle pressure, and there was plenty of air – the dive was just starting. But whether I understood it or not, it was becoming harder and harder to breathe – by the second. I finally took action by grabbing my dive-buddy’s octopus regulator (a back-up regulator), and together we slowly ascended to the surface.

Back on the boat I discovered my tank valve was not fully turned on. Why not, I wondered?

Well, the valve was worn, and generated a considerable resistance before it was fully open. As I am accustomed, I had turned the valve until I met resistance and stopped. That is a good way to prevent damaging a well working valve, but that particular tank valve was not working as smoothly as it should. It fooled me.

Chalk one up to lessons learned.

Without a doubt, the series of dive made from the Atlantic Clipper were among the most memorable of my diving career. In upcoming posts I’ll describe Red Sea dives at Sharm El Sheik and Ras Mohammad, followed by a dive at Herod’s Port, in old Caesarea, Israel.