Fatalities statistics: what kills people the most in scuba diving?

[John C. Ratliff]

Ken, that helped...but I'm still going through the report. One of the things that is striking is that the model DAN is using does not include the theory of multiple causation of factors that is the current model in professional safety. Many factors come together to cause an accident, and it isn't just one "trigger" event like is in the DAN model. Later today, I'll give an example from a diving fatality I investigated many years ago.

John

 

[John C. Ratliff]

Ken,

It took me a few more days to get back to this thread, and I apologize for the delay. This is a report on a scuba fatality that I investigated in 1987. I identified a number of contributing factors:

Contributing Factors

1. The diver was over-weighted on this dive, carrying a 20 pound weight belt in addition to 49 pounds in a Seapro At-pak.
2. Possible regulator malfunction--first stage. (A leak was found upon inspection of the gear.)
3. Possible regulator malfunction--second stage. (The regulator was missing the exhaust tee, which could have allowed water seepage into the second stage housing. This, along with the high suction pressure, could have allowed sea water to enter the diver's lungs in the form of a fine mist.)
4. Regulator malfunction--second stage. (Breathing resistance was measured to be very high.)
5. His BC would not hold air.
6. With gloves, it would be difficult to dump gear, including weights because he could not feel the Velcro-lined nylon on the vest.
7. Diving alone...no one in the water at the bottom to help him.
8. Out-of-air situation, most probably while underwater. This precluded him from inflating his BC (which leaked) or his dry suit.

These combination of factors came together to cause this fatality. Which one, under DAN's "trigger" theory started the sequence of events? I don't think any one of them alone was a trigger, but under current accident theory they all contributed to overwhelm the diver and cause the fatality. I'll get further into some of the accident theory later.

I have included my report to the police department, but have deleted the names of individuals in the report and the city itself, as this was long enough ago that they are not of interest in this report. I have also included a Scubapro set of graphs on breathing resistance of their Mark I second stage from 1974, which shows the different resistance readings on a new, in tune regulator of that era depending upon the number of turns in that are made to increase breathing resistance.

Because this is a basic scuba discussion forum, I feel that new divers need to know that they should have these adjustable regulators set for as easy a breathing as they can be, and only turn the adjusting knob in to prevent leaking from the second stage exhaust valve, or in current (which was their original reason for existing). DO NOT TURN THESE ADJUSTING KNOBS IN TO INCREASE RESISTANCE BECAUSE OF A SECOND STAGE LEAK THROUGH THE SEAT! THIS IS NOT THE INTENT OF PROVIDING THIS ADJUSTMENT. TURING THIS KNOB IN TO INCREASE BREATHING RESISTANCE COULD CAUSE DIVER RESPIRATORY FATIGUE AND BECOME A FACTOR IN AN INCIDENT, as it did in this example.

Also, if you buy used gear off E-Bay or used from someone, be sure to have it checked out and serviced prior to getting into open water with it. There could be an underlying malfunction or problem with the gear you are not aware of until you need it to perform correctly.

SeaRat

John C. Ratliff, CSP, CIH, MSPH

 

[jerzeedivr]

For that reason, 41%. I recommend using high pressure 120's or 130's tanks for diving in cold water like New Jersey. I sold my alum. 80's to someone that was going to wear them as doubles. A single 80 cu/ft tank is Not enough air for diving in cold water. Yes it will get the job done, but with little reserve. I have come too close to empty so, I now have 2 120's and 2 130's high pressure steel tanks and love them. There is less buoyancy with steel and less worries about running out of air! Don't risk your life with alum. 80's, its not worth it, I don't care if you call me an air hog. My friends call me the air bus. LOL. I'd rather have extra AIR!

I was at this conference and it was fantastic. We actually had a really good (and lengthy) discussion about this conference in this forum in mid-2010. I'm going to throw in some quick comments on a number of the posts that follow (and I think they'll all get lumped together) but this was my big takeway and what I consider to be the most significant stat from the conference:

Of the 947 fatalities, the trigger (incident that got the ball rolling) was identified in 350 cases.
Of those 350, 41% of the time, the trigger was running out of air.

What I think the takeaway is, is that running out of air is far more dangerous than we teach and that IF you run out of air, you have significantly increased the chances of dying on that particular dive.

- Ken

---------- Post added February 14th, 2013 at 05:52 PM ----------



Not really. Assume (as DEMA does) that you have 2 million active divers in the US & Canada. Assume they make ONE vacation trip per year, doing 2 dives per day for 5 days for a total of 10 dives. That's 20 million dives. And that's just US & Canada, diving here or abroad.

---------- Post added February 14th, 2013 at 06:03 PM ----------



The estimate is actually 2 million active US & Canada. US populaton 315 million, Canada 35 million = 350 million. 2 million active divers works out to about 0.6% of the total population. Sounds about right to me (and shows what a small sport we are). Futher, it's estimated by DEMA that 8 million people have either gotten certified or tried scuba (resort course) as far back as they can track stuff.

Participation stats for perspective (US):
Active golfers - 30 million
Tennis players - 23 million
Quilters - 21 million

---------- Post added February 14th, 2013 at 06:07 PM ----------



The other thing it doesn't deal with is something we see a lot nowadays: Someone got certified when they were 20, met another diver and got married, dove together for a few years, had kids and stopped diving, but re-entered the sport after a 20-year pause because now the kids are grown and they have time/money again. They may have tons of dives and been certified a long time, but there's a gap in terms of recent dives.

---------- Post added February 14th, 2013 at 06:15 PM ----------



Technically, cause of death will be something like drowning because the phrase "Cause of Death" really means "what was the mechanism of death"? The is what's great about the DAN 4-step method of analysis with (1) trigger, (2) disabling event, (3) disabling injury, (4) cause of death. Running out of air is the trigger, which causes panic & rapid ascent (disabling event), which causes embolsim (disabling injury), which cause drowning (mechanism of death).

But you're really splitting hairs IMHO. Then en result of not monitoring air (which would include having a reserve) IS running out of air. To me its like saying, "I didn't run out of gas. I simply had an absence of fuel."

 

[flots am]

Okay, I am going to ask a rather stupid question, but one that is bugging me...why is running out of air a life-threatening emergency in sport diving? I'll take answers, then give some opinions.

That's a trick question. Running out of air isn't dangerous. Handling it improperly is.

Running out of air (except in extremely rare cases of catastrophic hardware failure) is a huge sign of carelessness, but isn't particularly dangerous as long as the diver remembers and practices the skills taught in Open Water class.

It can be easily and safely handled with:

• A well trained buddy who is within easy air-sharing distance
• An Out of Air Ascent, followed by weight ditching if necessary
• A redundant air source

It becomes a potentially fatal problem for divers without a good buddy and good buddy skills, those that panic, or those that don't remember or can't execute the skills from their OW class, and those that think the "no-deco" border on the tables was produced with any significant amount of precision and applies personally to them.

edit: Was just thinking about this and the divers that run out of air are almost never the divers with sharp skills. so yeah I can see where "running out of air" would be dangerous. However it's more of a symptom of poor skills than being inherently dangerous.

---------- Post added February 25th, 2013 at 11:05 AM ----------

Short answer: No.

My GUESS/SPECULATION is that it's failure to monitor the pressure gauge. I have yet to see a case where equipment failure caused a diver to run out of air. (Not saying it hasn't happened, simply that I am unaware of it. If anyone knows of any and wish to post a counter to this, please give some details.)

(bold mine)

It's so phenomenally rare that I put it in a class of problems only slightly more possible than a bigfoot attack, but it has happened.

I'm aware of one case of a first stage that blew apart underwater. There might even be a video of it somewhere.

I'm also aware of a few (really a few) that ran out of air after becoming inverted, when the tank was both contaminated and had a missing dip tube.

The exploding regulator was an engineering or service problem that resulted in a recall and a part replacement, so I don't expect to see any of those again.

flots.

 

[Bob DBF]

Ken, that helped...but I'm still going through the report. One of the things that is striking is that the model DAN is using does not include the theory of multiple causation of factors that is the current model in professional safety. Many factors come together to cause an accident, and it isn't just one "trigger" event like is in the DAN model. Later today, I'll give an example from a diving fatality I investigated many years ago.

John

From my experience, one issue is not a trigger, it is a problem, and if it stays by itself it is just a problem. Since I started diving before the SPG, OOA dosen't trigger much, but that can be a double edged sword. The more amusing dives result from not correcting "small" problems and having them gang up on me during a dive until I run out of brainpower and or gas.

I now have "abort dive" as the first choice and only continue the dive if the issue is solved, no other problems have occurred, and I feel good about the rest of the dive. If I seem to have one little issue after another, I get out of the water and try again later. Somehow things don't get better by themselves underwater.

It seems to have worked for me over the years, I could have avoided a number of lessons if I had figured it out sooner.


Bob
-------------------------
I may be old, but I'm not dead yet.

 

[Amberjoy]

Many of you might have seen this link:
Alert Diver | The 2010 DAN Diving Fatalities Workshop

I thought it was a good idea to share with you some takeaway figures from these statistics. Some have particularly called my attention.

- They examined 940 fatalities that happened over a period of 10 years. The mortality rate is about only 4.7 deaths per million dives.

- 50% of the fatalities happened with people with less than 20 dives.

- Top 3 problems were: pre-existing health condition, poor buoyancy control, and rapid ascent or violent water movement.

- Equipment failure and marine life injuries are extremely rare. Not surprisingly, areas where divers notoriously cut corners, such as inadequate training or lax buddy practices, are far more likely to contribute to accidents. Forty percent of the fatalities took place during a period of buddy separation; 14 percent involved declared solo dives.

Great stats, thank you so much! Does the study include any reference to age or level of fitness as important factors in increasing the risk of death or injury?

 

[boulderjohn]

Great stats, thank you so much! Does the study include any reference to age or level of fitness as important factors in increasing the risk of death or injury?

DAN statistics have regularly shown that victims tend to have a high Body Mass Index (BMI), which is indicative of a tendency toward obesity. It is not, however, a clear measure, since a well-muscled athlete registers as obese according to the BMI. Victims also tend to be older--IIRC, the median age is around 47.

 

[flots am]

DAN statistics have regularly shown that victims tend to have a high Body Mass Index (BMI), which is indicative of a tendency toward obesity. It is not, however, a clear measure, since a well-muscled athlete registers as obese according to the BMI. Victims also tend to be older--IIRC, the median age is around 47.

Aside from the people who were days away from having a heart attack while watching television, I think a lot of the fatalities arise from people "handling" problems by becoming anxious or panicking.

Running out of air followed by panic, bolting for the surface and furiously treading water instead of ditching weights could easily cause a heart-attack in anybody in the "heart attack prone years", while running out of air, thinking "wow, I was dumb", followed by a calm ascent and oral inflation probably wouldn't cause anything more severe than embarrassment.

Unfortunately, DAN doesn't have any information on what happened before the heart attack.

flots.

 

[boulderjohn]

Unfortunately, DAN doesn't have any information on what happened before the heart attack.

flots.

Sure it does. In all cases where they have the information, they describe the events leading up to the death. You can read every one of them. I don't recall reading many--if any--cases such as you describe.

 

[flots am]

How could they possibly know whether the victims was being stressed by something preventable before death?

flots.