Technical Diving Accidents

Four causes are sufficient to explain the overwhelming majority of technical accidents: Inadequate experience or training, lack of or insufficient buoyancy control; improper gas; Insufficient gas or running out of it.

Steamer Detroit, Lake Huron, Michigan

94OCT- A deep-wreck diver made an emergency ascent from a depth greater than

200 f/61 m and got severely bent during a mix dive on the U.S. Detroit, a paddle wheeler sunk in 1854. The injured diver had ten years experience diving deep wrecks in the Great Lakes, having logged 200-300 dives, according to one of his companions. The Detroit was discovered last year and lies 18 miles offshore in an area of Michigan known as The Thumb.

The Diver was using trimix and independent doubles. He switched tanks and regulators when one of his regulators began to free flow. The diver decided to make an emergency ascent to an oxygen supply staged at 20 f/6 m for decompression, but ascended to the surface instead. The support crew administered oxygen and called a Coast Guard helicopter for medical evacuation. The diver underwent repeated decompression treatments and is walking today, but suffers residual damage from the incident.

Ethel-C, Virginia

94OCT- A diver died during a charter expedition to the freighter Ethel-C, sunk in 1960 off the Virginia coast. The 33-year old diver experienced a problem during his final decompression stop on the second dive of the day, lost consciousness and sank when other divers could neither inflate his BCD nor hang onto him. His body has not been recovered.

The former military diver, was reportedly in good physical condition and had extensive experience diving, although he had not done deep diving previously. He and two partners were diving air on the wreck, which rests at 185 f/57 m for a minute, then ascended to 170 f/52 m for 19 minutes. A decompression schedule of three minutes at 30 f/9 m on air, six minutes on O2 at 20 f/6 m and 18 minutes on O2 10 f/3 m was followed. The divers had a five-hour surface interval between the two dives.

After about two minutes into their 10 f/3 m stop, the diver’s head feel back and his regulator came out of his mouth. One of his two partners came to assist, but the other was not in the vicinity, apparently following a different decompression schedule. The partner tried unsuccessfully to inflate his BC using a power inflator button, but for an unknown reason could not, and was having difficulty holding on to the unconscious diver, who was not clipped to the station. Another diver came to assist and the partner ascended to the surface to notify the boat crew of the problem. The assisting diver could neither inflate the BC nor hold onto the diver, who sunk to the bottom. The surviving partner suffered decompression illness and had to be flown out by helicopter for treatment.

Neither the partner nor the assisting diver tried to remove the diver’s weight belt, and the partner did not attempt to orally inflate the BC. While the reason the BC did not inflate is unknown, one member of the group speculated that either the diver left his power inflator hose detached intentionally, without informing his partner, or could have run out of air, although the other divers believe he had 1,000 psi remaining in his tank. One report attributed the death to O2 seizure, while another theory is that the diver suffered from a heart condition called Prinzmetal’s angina, which has been linked to the other diving incidents.

Mayan Cenote, Mexico

95APR- Two experienced cave divers ran out of air and died after missing a turn while trying to exit a cave dive in Mexico. The two were among a group of seven cave divers who had broken into three teams for a 45-minute dive on air at depths no greater than 60 f/ 18 m. The pair was on the third team to enter the cave. Besides making an incorrect turn while trying to exit, the divers failed to use safety reels to mark a jump and apparently missed or disregarded a series of line markers pointing the direction to the exit.

On their way into the cave, all three teams used a main tunnel known as B. They passed in sequence through a T-turn, where the divers expected a jump. However, instead the cave came to a T, with three line markers marking the correct direction to turn while returning to go to the exit. A member of the second team repositioned one of the markers to make it more visible.

The third team into the cave called their dive earliest as planned, since the first two teams were stronger swimmers and wanted to penetrate further. The two divers then headed back, but turned in the wrong direction at the T, apparently missing all three line markers at the spot. Their mistake led them 300 f/91 m to the end of B tunnel, where another route leads to the A tunnel. The divers headed into the A tunnel, which also led to an exit, crossing a visual gap without setting up a safety reel to mark their path.

The divers then made a series of errors, apparently missing several indicators that should have told them that they were following a different path than the one they'd taken in. The divers made it to the end of the line marking the start of the A tunnel, about 30 feet from an exit. Rather than exiting, the team headed back into the A tunnel, passing as many as 14 line markers pointing back toward the entrance they'd just left. The divers then swam past the unmarked jump which might have led them back to the other dive teams.

When the third team did not return from the dive, the other five divers notified local authorities and asked for help. Later that day, the divers returned to the cave and recovered the bodies of the two divers. Their moves were reconstructed by the other members of the team, one of whom had entered the A tunnel after completing his dive in an attempt to find the missing divers. He noticed silt at the entrance, indicating that the missing team had recently been there, but because of low air had to turn back before going far enough into the tunnel to find them. One of the divers who died was 38 and had made between 75 and 100 cave dives; the other was 45 and had some 150 cave dives.

A cave diving instructor with the group commented that the series of errors apparently made were inexplicable given the level of experience between the two divers.

What happened to Sheck Exley?

by Bill Hamilton, Gordon Daughtery, Ann Kristovich, and Jim Bowden.

Excerpted with permission from the Undersea Hyperbaric Medical Society's newsletter, "Pressure."

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 "El Proyecto de Buceo Profundo" 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, "High pressure nervous Syndrome," 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 "stage" his air cylinder by clipping it to the line at 290 f. Bowden used a small "pony" cylinder carried on his back as his air supply. The divers switched to a "travel" 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, "Blueprint For Survival Revisited"-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 "80s" 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 "80" tank. A second side mounted "80" 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’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’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’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’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’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 "hot" 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 "deep water blackout" 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.

R.W. Bill Hamilton, Ph.D., is a physiologist and editor of Pressure. C.G. Daugherty, M.D., is a diving doctor specializing in occupational medicine. Ann Kristovich, DDS, is an oral surgeon and diver and medical officer for the Zacaton project. Jim Bowden is a diving instructor at the University of Texas and produced much of the material used in this article.

Bakerston Mine, Harpers Ferry, West Virginia

94JUL- A certified cave diver apparently embolized and died when his DPV trigger stuck in the "on" position dragging him to the ceiling of the cave following a gas switch from trimix to air at a depth of 200 f/61 m on the return leg of an exploration run. Prior to the switch, the diver had drained his doubles-violating the "thirds rule"- and was forced to share gas with his partner and swim for safety when his reserve cylinder regulator failed to function- the regulator hose being too short to permit scootering.

The team’s objective was to explore beyond the end of the existing permanent line at approximately 1650 f/503 m at a depth of 285 f/88 m. the team began the dive by motoring in 900 f/274 m to a depth of 200 f/61 m where they switched from air to trimix. The dive continued to a landmark known as "The Rock" at a depth of 250 f/78 m at 1200 ft/366 m. At this point the cave sloped to 270 f/83 m over a distance of several hundred feet (61 meters). The diver dropped his DPV due to the limited depth rating of the vehicle and swam as his partner slowly motored along. The end of the line was reached without incident at a depth of 285 f/86 m and the team added another 150 f/46 m of line to a depth of 305 f/94 m. The dive was called and the exit began.

The team returned to the staged DPV at 270 f/83 m at which point the diver attempted to switch to his reserve cylinder, his doubles being empty. Apparently, his regulator would not deliver any gas. Realizing there was a problem, his partner handed the diver a regulator from one of his two trimix stage bottles, however, the short hose made it impossible to motor so the team swam their DPV’s back to The Rock. At this point, the diver switched back to his air stage and the team motored approximately 300 f/91 m up the ledge to the big room at a depth of 200 f/61 m.

Once they entered the room, his partner felt a DPV blast and saw a flash of light. He turned to find the diver unconscious on the ceiling- the DPV running circles around him. The trigger was stuck "on." There was blood in the diver’s mask. He cut away the DPV and tried to hold a regulator in the diver’s mouth with no response. The partner then attempted to tow him out but had to leave the diver to complete his own decompression.

The recovery team had no problems locating and extracting the body. All equipment was functioning properly, including all regulators. The doubles were empty and the single 80 with trimix was full with the regulator working properly.

The diver had a reputation for violating the thirds rule, had previously run out of gas on at least three cave dives, and had experienced "deep water blackout" (where a deep air diver is rendered unconscious) at 210 f/65 m while switching from bottom mix to air during a previous dive to the site and survived. An astute dive partner held his regulator in his mouth until he regained consciousness.

Lusitania, Kinsale, Ireland

94AUG-Two months after the Tapson expedition was completed without incident, a 37 year old diver "blew up" to the surface from a 280 f/86 m trimix dive on the Lusitania, incurring severe injuries.

After descending to the wreck, the diver’s partner began to lay line form a descent line. The two became separated when the diver’s stage cylinder came undone from his harness. He tried unsuccessfully to reattach the cylinder and in the process, became severely entangled in the line. He then dropped a cutting too that he had intended to use to disentangle himself. His partner returned to assist and cut him free, but the diver apparently panicked and blew up the surface legs first. He was diving on a trimix 12/26 (12% O2, 26% He, balance N2) and his surface to surface interval was about 12 minutes.

The injured diver was flown to the Naval recompression chamber at Haulbowline near Cork, Ireland. On arrival, the injured diver was weak but moving all limbs with good preservation of cortical function and absolutely no evidence of pulmonary barotrauma. His condition continued to worsen and he was treated with little success.

The diver had been certified for nitrox and trimix diving less than four months before his accident and had been advised by his instructor that his experience level was insufficient to attempt the Lusitania in 1994 without more experience. It is unknown whether the diver, who is now a quadriplegic, will ever walk again.

Sheck Exley: Preliminary Accident Report

On 6 April 1994, Sheck Exley and Jim Bowden of Austin, Texas, submerged on a deep cave dive that both hoped would carry them to a new world of cave diving depth record of 1,000 f/307 m. Exley, the holder of the current mixed gas open circuit record of 881 f/271 m set last year at Bushmansgat, South Africa, did not return from cave.

The dive site known as Pit 6350 or Zacaton is located near the small town of Aldama some 60 miles north of Tampico, Mexico. The pit is approached first by traversing a 600 foot long underwater passage with a maximum depth of 50 f/15 m to reach a large round open air lake. The divers could not enter the pit directly because of the 60 to 70 foot sheer cliffs surrounding the lake. The lake had been previously plumbed around its circumference by Exley and found to exceed 1,000 f/307 m on all sides. Two separate descent lines were rigged, one for Exley and the second for Bowden. While they both dived at about the same time, the separation of the lines was such that both divers were relatively unaware of each other during the dive.

When Exley’s bubbles did not reappear on the surface when expected, safety diver, Mary Ellen Eckhoff descended to a ledge at 270 f/83 m to check, and found Exley’s dive tables floating upward. No bubbles were seen ascending from depth. Later when the descent lines were being hauled up, Exley’s body was pulled to the surface. His depth indicator showed that he had reached 904 f/278 m.

It is unlikely that the course of events leading to this tragedy will be known with certainty. A careful, more detailed analysis of the facts known about the dive, the dive plan, and an analysis of potential causes of the accident is being undertaken as Exley would have wanted. This analysis will be published in a future issue of aquaCorps.

This accident marks the passing of one of the world’s greatest cave divers. All his friends and family took comfort knowing that Sheck passed away doing what he loved most. Or perhaps, Sheck is as he was in life, merely one step ahead of the rest of us, exploring the caves in the Great Beyond. He will be missed.

-submitted by John Zumrick.

Huautla Expedition: Fatality Report

On 27MAR1994, British cave diver Ian Roland died whilst exploring the terminal sump in Sotano San Agustin, part of the Systema Huautla, in Oaxaca, Mexico. A member of the expedition team, Roland was diving the prototype rebreather system under development by Bill Stone.

At 08.00 on the 27th, Ian had dived from Camp Five for a 380 m/1246 f penetration. Dive time was 53 minutes at a maximum depth of 26 m/85 f.

At 11.00 Kenny Broad continued the exploration, surfacing in a large air bell at 430 m/1410 f. The chamber was approx. 20m wide and 20m high (65 feet x 65 feet) with large sandbars. There was not sound of running water or air movement. Kenny returned to base without exiting the water. At 16.00 Roland set out to explore the chamber. He estimated a return time of three hours but said not to worry for six.

At 19.00 Broad, concerned by Roland’s non-appearance, began to assemble the second rebreather rig. At 22.00 he set out to Camp Three to alert the support party. They returned to Camp Five in due course and completed the assembly and checking of the second rig. At 12.15 on 28MAR, Broad began the dive through to the chamber. He carried emergency medical supplies (Roland was diabetic), food and bivouac equipment. At 12.41 he surfaced in the chamber and noted foot-prints on the sand bar. He swam alongside the bar, in clear water, and continued beyond its end for 10 m/33 f at which point he located Roland’s body resting on its right side. Resuscitation was futile.

Broad noted that the line reel appeared to have fallen out of Roland’s hand. Four out of five tanks were full and the control system was functional. The mouthpiece was in closed circuit position and out of the mouth; the O2 "setpoint" was 0.5 atmospheres; the O2 control valve was in manual shut off position and the PO2 was 0.17 atmospheres (heliox 14/86). There was no sign of struggle or distress. The body was recovered by team members, assisted by Mexican cavers and members of a British expedition, in an operation which took six days.

Observations during the recovery showed that the control system was still active and the heads up and buddy displays were both flashing red, indicating a PO2 below 0.21 atm. The left diluent tank was empty. Black box data records that were retrieved from the rig, show that the tank was emptied over a seven minute interval following Roland’s loss of the mouthpiece as the rig attempted to maintain counterlung volume. Functional tests were made on the rig back at the base. All systems were operational and within specification.

Roland had eaten a normal breakfast in the morning buy was suffering from mild diarrhea. He had taken two food bars which were not eaten. There was not sign that Roland had doffed & donned the rig when leaving the water. These items had combined the weight of approximately 140 pounds, therefore traversing the airbell would have involved a significant exertion. The oxygen injector unit on the rig was manually switched off. This is a common procedure upon surfacing which conserves oxygen. Normal procedure would have been to re-enable the unit upon re-entering the water.

Given that his rebreather appeared to be fully functional, it was initially presumed that Roland’s death was due to operator error based on the closed position of the O2 valve. However, black box data clearly indicates that at the time of what was apparently an uncontrolled descent from the surface to 9 f/2.8 m, the PO2 of the breathing mix was 0.24 atm, i.e. not hypoxic, indicating Roland’s blackout was due to some other cause. The observed PO2 of 0.17 atm resulted from purging of the gas processor with 14/86 heliox during the descent. It’s subsequent stability at 0.17 atm indicates that Roland was not breathing form the rig following initiation of the descent.

Based on his dive line, it was clear that Roland was returning to the sand bar from the head of Sump 2 after apparently realizing something was wrong. Given that Roland was a diabetic and had not recently eaten; that heavy exercise, and mental impairment was present (evidenced by the failure to re-enable to O2 valve) it has been concluded that the black out was caused by hypoglycemia and/or related events such as arrhythmia or seizure. Roland was extremely meticulous cave diver and had logged more than 60 hours on rebreathers. He was, however, a recently diagnosed diabetic and did not have a blood glucose test kit in the cave.

-submitted by Rob Parker & Bill Stone

Sydney, Australia

MAR94-A very experienced technical diver, PADI and NAUI instructor and ANDI nitrox instructor trainer, mistakenly breathed his EAN 50 (50% O2, balance nitrogen) decompression mix during a wreck dive to 50 m/164 f (PO2 = 3.0) on the Coolooli, and convulsed and drowned 18 minutes into the dive. Efforts to resuscitate the 47-year-old diver were unsuccessful. The diver was diving air supplemented with EAN 50 mix for decompression-a common practice among Sydney wreck divers. Reportedly, the diver carried both his bottom and decompression mix on his back and ran both through a switchable manifold block. Several colleagues apparently talked about the shortcomings of this configuration with the diver without success. An analysis of the contents of the tanks showed that the diver breathed EAN50 during the duration of the dive. He convulsed just as he and his tow dive partners began their ascent.

Abaco, Bahamas

94APR-Three "untrained" open water divers ran out of gas and drowned in the Big Boil Blue Hole cave system. None of the divers were cavern or cave certified.

It was reported that the three divers entered the low and silty Big Boil cave with only two guide lines. Two of the divers carried single 72 cf tanks. The third carried a single 80 cf tank.

The team leader who reportedly had "dived Big Boil many times before," made the dive without a depth gauge, BC, knife or redundant second stage. The team apparently made about 150 foot/46 meters penetration to a depth of 75 f/23 m.

Two of the bodies were recovered on the main line at what is believed to have been their point of maximum penetration. One of the divers was tangled in the line. The body of the team leader was located after an extensive search, in a restricted side passage approximately 150 feet/46 meters off the main line.

-submitted by Al Pertner

Grand Bahamas

94MAY-Two very experienced divers who were not cave certified, got lost in a popular Blue Hole during a live-aboard dive trip, ran out of gas and drowned. Neither diver was running a line or carrying multiple lights.

One of the divers was found within 100 feet/30 m of the cavern zone in about 90 f/28 m. The second body was recovered by a cave recovery team the next day at about 400 feet/122 meters from the cave entrance in about 120 f/37 m of water. Both were wearing single 80 cf tanks. It is not known if the bodies were separated by the tidal flow in the system or if the team had been separated during the dive.

The cavern zone at the site is often dived by recreational divers from a liveaboard. A partner of one of the deceased who was on the dive boat believed that the two "had no intention of making a cave dive," and in fact, had left line reels on the boat. One of the divers was going shell collecting. The other was apparently planning to shoot video. The partner believes that the two got intrigued an ventured out of the cavern zone into the cave system. Ironically, the two were considered the most experienced divers on the liveaboard trip. One of the divers was a former commercial and military diver, was open circuit mix trained and had worked as a divemaster with a technical diving operation. The other was a dive store owner, a 20 year instructor and was in the process of completing a cave course.

Near Tragic Mix-Up

On 9JUL my son Jonathan asked if he could scuba in our backyard pool. Jon is almost 12 years old and has been using scuba in the pool for two years. I didn’t really want to but after relentless asking, I gave in. It was around 7 p.m. so instead of using his usual 30 cubic foot (cf) pony bottle, I grabbed a yellow 14 cf pony for him from the stack. He geared up and we went in the pool.

I sat on the diving board as Jon entered the low end of the pool. My younger son, Bryon sat on the stairs. Jon went underwater and after a few minutes something seemed wrong. I went to the low end of the pool and Bryon shouted "Something’s wrong Dad." Bryon grabbed the skimmer pole and poked Jon who was floating face down. He didn’t respond. I jumped in the water and pulled him up. He was blue and not breathing. I got him out of the pool into the deck and started CPR. He had a pulse but was not breathing. After rescue breathing, for what seemed like eternity, I was able to restore his breathing. My wife Jean had called 911 (a US-wide emergency hotline-ed.) and the rescue personnel arrived several minutes later.

As I was explaining what happened to one of the rescue teams, I looked into the pool and saw the yellow 14 cf pony floating where Jon had been. Then it struck me like a ton of bricks. When I first started using argon gas for suit inflation, I committed a cardinal sin. I failed to paint the bottle brown or to properly label it as containing argon. After obtaining a proper argon bottle, I thought I had drained the 14 cf pony, but I hadn’t. Somehow I had it mixed up with my other pony bottles. When Jonathan went diving, I had picked up that bottle out of the stack. It was lack of caution and it almost cost me my son. Thank goodness, Jonathan has completely recovered with no lasting effects.

It is of the utmost importance that all types of gases be properly marked, that the required types of values and regulators be used, and that different gases be stored independently of each other (Note that Compressed Gas Association, CGA, conventions require that special connectors be used for each type of gas to avoid mix-up - ed.). I consider myself a careful and responsible person, however negligence, whether intentional or not, can be deadly in our sport. If writing this letter averts just one tragedy, then the horror we went through will not be in vain.

-submitted by Bill Delmonico, Scituate, RI

South Coast of England

93JUL-An experienced wreck diver failed to surface following an air dive to 109 fsw/58 msw on the Merchant Royal and is assumed dead. The diver had become separated from her partner on the wreck who surfaced with the minimum required decompression and raised the alarm. Though visibility was excellent the body was never found during the ensuing two day search. The diver had been wearing twin 12 liter independent cylinders (about 200 cf) and a pony with decompression gas. She dived regularly to these depths and was reported to be a strong dependable diver.

-submitted by Simon & Polly Tapson, London, England

Sydney, Australia

93AUG-A wreck diver lost consciousness during a 15 minute deep air dive to 78 msw/254 fsw on the paddle tug, Koputai, and drowned. The diver lost consciousness while returning to the anchor line after a 15 minute planned bottom time to make his ascent. Though his three partners attempted to ascend with the diver in tow, they were unable to maintain a regulator in his mouth and he subsequently drowned. The team preceded to lift the unconsciousness diver to 15 msw/50 fsw and released him to surface. Surface support personnel initiated EAR and radioed for emergency assistance/evacuation. The diver did not regain consciousness and was pronounced dead a short time later. Though the Coroner’s report has not been released, CNS toxicity (working PO2 = 1.85 atm) compounded by possible CO2 build-up and narcosis-characteristic of deep air dives-is suspected as the primary causal factor. The incident raised government concerns about local deep diving practices. Though mix training has just gotten started in Australia, most deep dives are still conducted on air.

-Submitted by Richard Taylor, Sydney, Australia.

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