Overview
Overview
2006 has seen a drop back in the number of incidents reported; a total of 379.The chart below shows the total of UK incidents reported annually over the last 16 years and it can be seen that after a doubling during the 90s, we now seem to be seeing a levelling out from 2000 onwards to a total of 400 incidents per year.
Incident year
The distribution of reported incidents is shown in the following chart. As can be seen, 65% of these incidents have occurred in the summer period.This is totally consistent with previous years, reflecting the increased number of dives that take place during the warmer weather.
There is a lower than normal number of reported incidents in both March and May.There is no obvious reason for this except that Easter was in the middle of April and divers may have chosen to centre their dives at that time of year around the Easter holiday weekend.
Incidents by month - 2006
Incidents by category The incident database categorises all incidents into one of nine major categories, and the following chart shows the distribution of the 2006 incidents into those categories. The highest number of incidents (105) relate to ‘Decompression Illness (DCI)' and this is consistent with previous years. Ascent related incidents are the next major category with a total of 99 incidents recorded in the group. In previous reports it has been noted that this type of incident is on the increase and this year’s number is an all time high. Typically these incidents involve a rapid ascent, often with missed decompression stops,However, if such an ascent were to have resulted in a DCI then it would have been recorded in the more serious DCI category.
More detail on DCI, Ascent and Boat / Surface incidents can be found later in this overview together with an analysis of the most serious category; Fatalities.
Categorisation of all the year's incidents
Incident depths
The following chart shows the maximum depth of the dives during which incidents took place categorised into depth range groupings.
Maximum depth of dive involving an incident
The pattern of depths in the 0m to 50m range is very similar to that normally seen and reflects the amount of diving that takes place in these depth ranges.The number of incidents reported in the greater than 50m range is 10, which is in line with previous years.One of these incidents was a fatality.
The BSAC advises that no air dive should be deeper than 50m, and that dives to 50m should only be conducted by divers who are appropriately trained and qualified.
The recommended limit for divers trained to Sports Diver standard is 35m and then only when they have received appropriate training for diving at this depth.
The BSAC recommends that mixed gas diving should be to a maximum depth of 80m and then only when the diver holds a recognized qualification to conduct such dives.
The next chart shows the depth at which the incident started.
Depth at which an incident started
Number of incidents
Number of incidents
Inevitably the data are biased towards the shallower depths since many incidents happen during the ascent or at the surface.Critical among these are the DCI cases where almost always the casualty is out of the water before any problems are noted.This partially explains the large occurrence of ‘Surface’ cases as this includes divers with DCI who have left the water.
Other surface incidents involve boats and boating incidents.
Diver qualifications
The next two charts show the qualification of those BSAC members who were involved in reported incidents.
The first looks at the diver qualification.
Qualification of the divers involved in incidents
Number of divers
These data are in line with the normal pattern of previous years and to some extent reflect the number of divers in these qualification grades.
The next chart shows an analysis of incident by instructor qualification and again it is consistent with previous years.
Qualification of instructors involved in incidents
Number of instructors
Divers’ use of the emergency services shows a monthly distribution aligned to the distribution of all incidents, and is clearly correlated with the number of dives that are taking place.
Our demands upon the Coastguard service have dropped dramatically this year with only 178 incidents reported that involved the Coastguard.This number is the lowest in the last 9 years where the average has been 211 Coastguard related incidents per year.Only future years will tell us if this 16% reduction from the average is an anomaly or the beginning of a trend.
Incidents involving the UK Coast guard agency
- Monthly breakdown
Number of instructors
Divers’ use of RNLI facilities by incident year
incident year
The following chart shows the distribution of the RNLI related incidents throughout this incident year.It is in line with the other monthly based data, except that it does not show the dip in May seen elsewhere.
Divers’ use of RNLI facilities by month
Divers’ use of SAR helicopters by month
In 2006 105 incidents involved the use of helicopters, and this is significantly lower than the high of 137 recorded in 2005.105 is the lowest use of helicopters recorded in the last 5 years and seems to be in line with the overall reduction in reported incidents.Helicopters are often tasked to support searches for missing divers and to transport divers with DCI to recompression facilities.
Fatalities
16 fatal incidents occurred in the UK during the 2006 incident year.This is a little below the average of 17.7 fatalities per year over the previous ten years although comparisons of this nature need to be made with caution since a small change can make a big apparent difference to the comparison.
2004 saw 25 fatalities and raised concerns that we might be experiencing the beginnings of a trend of increasing fatalities.At the time the BSAC argued that this unfortunate number was simply the result of natural perturbations of very small numbers in a very large sample, compounded with the timing of the incidents and the timing of our incident year.The 2005 coupled with the 2006 findings indicate that this argument was valid.
4 of the 16 fatalities were BSAC members.
- The factors associated with these fatalities can be summarised as follows:-
- One case involved a diver who suffered a heart attack.There is a second case (and may be others) which may also be included in this group when the full facts are made known.
- Three cases involved divers who were, or who became, negatively buoyant and sank.In one case a diver was at the surface, in difficulties, but was unable to remain at the surface and sank before he could be recovered.In two other cases divers were negatively buoyant underwater, in difficulties, and sank.
- Seven cases involved separation.
In each of these cases the separation was not planned.
Four cases involved divers who became separated from their buddies and were then found unconscious or semi-conscious at the surface.
The other three cases involved divers who became separated underwater and failed to surface. - Four cases involved equipment.In two cases it is likely that a rigorous buddy check would have prevented the problem.Two cases involved regulator problems, one of which was a free flow.
- Two cases involved solo diving.One case involved a rebreather diver.The other case was a cave diver whose absence was noted 24 hours later.
- Two cases involved divers running out of breathing gas
- One case was compounded by buoyancy problems and the other involved a free flow which prevented a buddy from assisting the casualty.
- Three cases involved rebreathers.
- Three cases involved incidents that were initiated or made more difficult by water currents.
- Three cases involved divers with DCI.Two divers suffered fatal pulmonary embolisms and a third diver suffered a cerebral embolism.Two of these cases involved uncontrolled ascents but one occurred after an apparently normal dive.
- Two cases involved three divers diving together.
- One case involved a depth greater than 50m.This was a diver who dived to 66m and surfaced missing all decompression stops and suffered an embolism.
Often multiple causes were involved in an incident and in eight of these fatal incidents there is insufficient information available to be clear about the exact chain of events and root causes.
As stated above only one of these cases involved a dive to greater than 50m. In previous years I have highlighted the disproportionate number of deaths related to deep diving.Typically there have been 4 to 6 fatalities in this depth range and, as I have pointed out before, this must be out of proportion to the amount of diving that takes place in these depths.2005 saw two deaths from dives deeper than 50m and this year saw only one; I hope that this trend holds.
Finally there were three reported fatality overseas.One case involved the double fatality of two BSAC members who had been diving to a depth of 80m using rebreathers with trimix.The third case involved BSAC members in the death of a non member, where the casualty was apparently trapped, lost, inside a wreck in a depth of 50m.
Decompression incidents
The BSAC database contains 105 reports of DCI incidents in the 2006 incident year, some of which involved more than one casualty.When these multiple cases are counted the result is 112 cases of DCI.
This number continues the decline in cases of DCI from a peak of 173 individual cases reported in 2002 and returns us to the typical levels reported in the late 90s.
An analysis of the causal factors associated with the cases for 2006 indicates the following major features:-
Some cases involved more than one of these causes.35 involved diving to deeper than 30m30 involved rapid ascents27 involved repeat diving15 involved missed decompression stops
Whilst cases of DCI may have declined, as reported earlier, cases of abnormal ascent (rapid ascent and/or missed stops) have significantly increased, and it may just be a case of good fortune that these abnormal ascents did not resulted in DCI.
Some of the ‘Injury and Illness’ incidents are also thought to be DCI related, but they are reported by the RNLI as ‘Diver illness’ and the cause of the illness is not defined.
Ascent related incidents
In previous years I have highlighted the rise in the number of incidents associated with abnormal ascents.This year’s report contains 99 ascent related incidents, the highest number ever recorded and a clear indicator that this is an area that requires a lot more attention from divers.
The following analysis reveals some of the issues:-
Basic nature of the report:-
Causal factors are:-
Again some have a combination of the above factors
When all of the above causal factors are excluded 53 incidents (53%) remain where a simple loss of buoyancy control seems to have been the cause.Without any of the above perturbing factors being present divers have simply been unable to correctly control their rate of ascent.Poor training and lack of skill are the only explanations.These are avoidable problems and instructors should make this a priority area for attention.
Many DCI cases have their roots in these problems; they have been recorded under the DCI heading but the causal factors are often the same, so the actual number of abnormal ascents will be significantly higher than shown above.
Boating and surface incidents
'Boating and Surface' incidents are the third largest category.Recent years have seen a very marked decline in the number of these incidents from a maximum of 124 in 1998.The 2006 numbers at 66 continue that trend strongly.The decline in these incidents and the increase in ‘Ascent’ related incidents has displaced ‘Boating and Surface’ from its traditional second place.
Divers are to be commended for this reduction, it results from a combination of less lost divers and less engine failures.It is a subject that has received a lot of attention and it is good to see that divers’ actions in these areas have had an impact.Incidents in this category often result in calls upon the Coastguard and the RNLI and some of the reduction in our need for support from the emergency services is down to this improvement.
Conclusions
Key conclusions are:-
Remember you can never have too much practice and the further you stay away from the limits of your own personal capabilities the more likely you are to continue to enjoy your diving.
Please browse through the details in this report and use them to learn from others’ mistakes. They have had the courage and generosity to record their experiences for publication, the least that we can do is to use this information to avoid similar problems.
Finally, if you must have an incident please report it on our Incident Report form, available free from BSAC HQ or via the BSAC website.
As always, your anonymity is assured – great care is taken to preserve the confidentiality of any personal information recorded in BSAC Incident Reports.
Basic nature of the report:-
88 Rapid ascentsClearly some incidents relate to both the above
32 Missed stops
Causal factors are:-
18 Drysuit or BCD issues
16 Delayed SMB, Mask, Fin problems
12 Free flows
10 Out of air
6 Weight related issues
2 Training
Again some have a combination of the above factors
When all of the above causal factors are excluded 53 incidents (53%) remain where a simple loss of buoyancy control seems to have been the cause.Without any of the above perturbing factors being present divers have simply been unable to correctly control their rate of ascent.Poor training and lack of skill are the only explanations.These are avoidable problems and instructors should make this a priority area for attention.
Many DCI cases have their roots in these problems; they have been recorded under the DCI heading but the causal factors are often the same, so the actual number of abnormal ascents will be significantly higher than shown above.
Boating and surface incidents
'Boating and Surface' incidents are the third largest category.Recent years have seen a very marked decline in the number of these incidents from a maximum of 124 in 1998.The 2006 numbers at 66 continue that trend strongly.The decline in these incidents and the increase in ‘Ascent’ related incidents has displaced ‘Boating and Surface’ from its traditional second place.
Divers are to be commended for this reduction, it results from a combination of less lost divers and less engine failures.It is a subject that has received a lot of attention and it is good to see that divers’ actions in these areas have had an impact.Incidents in this category often result in calls upon the Coastguard and the RNLI and some of the reduction in our need for support from the emergency services is down to this improvement.
Conclusions
Key conclusions are:-
- Reported incidents are down this year and suggest a levelling off in the number of annually reported incidents at approximately 400 per year
- The number of fatalities is a little below the norm of previous years.
- No new causal factors for fatalities have been identified.Continuous skills practice, rigorous buddy checks and diving within one’s current ability limits with a slow progression to new areas are the critical keys to safe diving.
- Incidents associated with abnormal ascents continue to rise dramatically and attention must be given to training in this area and the continuous practice of ascent skills.
Remember you can never have too much practice and the further you stay away from the limits of your own personal capabilities the more likely you are to continue to enjoy your diving.
Please browse through the details in this report and use them to learn from others’ mistakes. They have had the courage and generosity to record their experiences for publication, the least that we can do is to use this information to avoid similar problems.
Finally, if you must have an incident please report it on our Incident Report form, available free from BSAC HQ or via the BSAC website.
As always, your anonymity is assured – great care is taken to preserve the confidentiality of any personal information recorded in BSAC Incident Reports.
Page last modified: 21st Dec 2006 - 17:50:30