The Truth behind Dive Accidents: The DAN Report

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There’s a familiar character dangerous to the world of diving; the one that got certified a long time ago, his equipment has been stored in a trunk in the attic without regular service and he’s put on a few pounds since his last dive holiday.
He doesn’t think he needs to take a refresher course and signs up for dives beyond his training and experience. After a stressful first dive with leaking equipment in strenuous conditions his over exertion leads to perceptual narrowing and panic: the rapid ascent leads to air embolism in a matter of unpredictable seconds.

This scenario has happened and is found in the latest annual report of accidents and fatalities from the Divers Alert Network (DAN). It claims fatal dive accidents often have multiple and complex root causes; not just one solo event. Dr. Peter Denoble, DAN’s research director, says: “While each accident may be different and some of them occur in an instant, most accidents can be represented as a chain of multiple events that lead to deadly outcome. Removing any link from that chain may change the outcome.”

Based on the data contained in The DAN Report, the following contributing factors can lead to fatal dive accidents:

Procedural Errors

These include: buoyancy control problems, rapid ascents, omitting decompression stops, general skill limitations, ear equalization problems and failing to properly monitor the air supply: resulting in low-on-air or out-of-air situations. In some cases, the diver lacked the appropriate training for specialized activities like diving in overhead environments (caves or wrecks) or deep diving. In other cases, the diver stayed within the scope of his training, but his emergency response skills simply weren’t executed well enough.

In 26 percent of all the fatalities in the report, an emergency ascent was the precipitating factor leading to the actual cause of death, but there were often other procedural errors that triggered the ascent. Insufficient gas supply was the triggering event in 14 percent of cases; the inability to deal with rough seas and strong current ranked second at 10 percent; followed by health problems at 9 percent; entrapment or entanglement at 9 percent; and equipment problems at 8 percent.

Poor Health

Obesity, heart disease, high blood pressure, breathing difficulties (temporary or chronic), a general lack of fitness, pre-existing injuries and dehydration:  Almost any pre-existing medical condition or health factor can affect a diver’s safety.  The biggest contributing factor-cited in 74 percent of the fatal cases covered by the study-involved divers with a body mass index in the overweight, obese or morbidly obese categories. And approximately 15 percent of fatalities examined by the study involved people who were known to have high blood pressure or heart disease.

It is important to go for a medical checkup before every diving holiday if you know you have these issues or at an age where they are likely to occur.

In addition to the long-term health issues common illnesses like colds and stomach problems can be problematic. Working as a diving instructor for 3 years I have witnessed on 2 separate occasions 2 colleagues falling victim of decompression illness following a normal, shallow dive profile just because of dehydration following a stomach illness.

Environmental Issues

Open-water conditions can change rapidly and divers that are out of practice, unprepared or physically incapable of adapting to those changes can become victims.

Evaluate temperatures, currents, wave action, depth and visibility, etc. Not all diving is the same. Gong from warm to cold water or shallow to deep when you’re not acclimatized to the type of dive can introduce some new warning factors. Shallow-water divers are often surprised by how rapidly they use their air supply and by the impact of narcosis on their first dives in the 100-foot range.

Equipment Problems

While equipment failures account for relatively few fatalities covered in the DAN study they are one of the most predictable-and easily preventable-causes of fatal dive accidents. According to the study, BC issues were involved in 7.5 percent of the fatalities; regulator issues in 6 percent; weight systems in 5 percent; and mask, fins, dry suit and computer failures were involved in less than 3 percent each. It is important to note that this does not mean that the equipment failure actually caused the fatality. Ultimately, the diver’s reaction to an equipment failure is more likely to impact the outcome of the incident than the actual failure itself.

Equipment issues are often obvious before the dive and the observant diver can effectively make a preemptive self-rescue before he ever enters the water. The best policy is to check your equipment thoroughly before you board the dive boat, maintain your gear carefully and follow all recommended service intervals.

Tips for Avoiding Accidents. 

  • Dive within the limits of your training. Get proper training before attempting any dive above your skill level.
  • Get the right equipment. All life-support equipment should be properly maintained, serviced regularly and inspected before every dive.
  • Take a refresher course. Even when diving within the limits of your training, take a refresher course to shake off the rust from a long lay-off. A little time spent in the pool before you take that trip-of-a-lifetime vacation will pay big dividends. You’ll dive safer and you’ll have more fun because you will be more confident. Here at Rich Coast Diving we require all divers less than Divemaster level take a refresher if it has been over a year out of the water.
  • Get rescue certified. Every diver should know how to respond in an emergency, but the primary benefit of this class is that it will teach you to be responsible for your own safety.
  • Practice safety skills. Practice critical dive skills, such as flooding and clearing your mask, recovering your reg, sharing air, etc.
  • Stay in shape for diving. See your doctor about any medical condition that may limit your ability to dive safely.
  • Stay within your personal limits. Don’t make any dive you’re not comfortable with. There is nothing wrong with saying no, at least until you have the chance to get the appropriate training.
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