| PREDISPOSING FACTORS |
| Health-related: |
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• A diver with significant cardiovascular disease may be predisposed to a cardiac event with immersion and/or exertion. |
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• A diver who is intoxicated is at an increased risk of making poor decisions. |
| Organisational/training/experience/skills-related: |
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• A dive organisation offers services to non-English-speaking (NES) clientele. A NES group booked for a dive and no arrangements were made to translate the dive briefing into the clients’ language. As a result, several divers act contrary to the brief and one subsequently dies. |
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• A person untrained or poorly trained in the use of a buoyancy compensator device may be more likely to have a buoyancy-related problem, so triggering an accident. |
| Planning-related: |
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• A diver went diving alone and without a lookout to retrieve a craypot. He became entangled in a line and was unable to free himself. |
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• When two divers arrived at their planned dive site, although there were large waves constantly breaking over the entry and exit points from the rocks, they decided to dive there anyway. When trying to enter the water, one diver was swept off the ledge, struck his head on rocks and drowned. |
| Poor communication or co-ordination: |
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• One of a buddy pair was aware of a strong current on the other side of a 'swim-through', but failed to communicate this to the other, who subsequently swam into the current and was swept away. |
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• Regulator, surface-supplied breathing apparatus or rebreather functional problem leading to gas supply reduction or interruption; |
| Absence of appropriate equipment or using obviously faulty equipment: |
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• A diver who dives without a BCD may be predisposed to a buoyancy-related problem. |
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• A diver who dives with air from a faulty or poorly maintained compressor may be predisposed to contaminated air. |
| Unsafe supervision: |
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• Poor supervision by the divemaster and/or buddy may result in an inexperienced diver entering the water without all equipment in place and functional and so predispose to an accident. |
| TRIGGERS |
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Environment-related:Faulty depth or contents gauge; |
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• A diver got into difficulties while struggling to make headway against a strong current. |
| Trigger = Environment-related (current) |
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• A spearfisherman was confronted by an aggressive shark. |
| Predisposing: Activity-related (collecting seafood). |
| Trigger = Environment-related (shark) |
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• A diver breathing air at a depth of 55 metres' sea water was suffering severe narcosis, misread his contents gauge and ran out of air. |
| Predisposing: Activity-related (deep air diving) |
| Trigger = Environment-related (narcosis at depth) |
| Equipment-related: |
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• A diver's BCD inflator became stuck open resulting in a buoyant ascent. |
| Trigger = Equipment-related (sticky BCD inflator) |
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• A diver's regulator failed, causing a loss of air supply. |
| Trigger = Equipment–related (regulator failure) |
| Gas supply-related: |
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• A technical diver using a rebreather became unconscious at depth due to hypercapnia resulting from overloading of the CO₂ scrubber. |
| Predisposing = Faulty equipment (CO₂ scrubber inadequate) |
| Trigger = Gas supply-related (CO₂ scrubber exhausted) |
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• A diver ran out of breathing gas while trying to complete required decompression and was forced to make a rapid ascent. |
| Predisposing = Poor planning (unless something unpredictable occurred) |
| Trigger = Gas supply-related (out of gas) |
| Buoyancy-related: |
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• After deploying his surface marker buoy (SMB), a diver became entangled in its line and was dragged to the surface. |
| Trigger = Buoyancy-related (SMB entanglement) |
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• An inexperienced drysuit user became inverted, was unable to dump air from the suit and had an uncontrolled ascent. |
| Predisposing = Experience-related (inexperienced) |
| Trigger = Buoyancy-related (drysuit blow-up) |
| Exertion-related: |
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• A (healthy) diver collecting abalone became exhausted and distressed while dragging his heavy catch bag and then struggled to stay afloat on reaching the surface. |
| Trigger = Exertion-related (heavy catch bag) |
| Anxiety/stress-related: |
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• A student on an introductory dive was seen to panic and rush to the surface after encountering a large stingray. |
| Predisposing = Experience-related (inexperience) |
| Trigger = Anxiety/stress-related (panic from stingray encounter) |
| Primary diver error: |
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• A rebreather diver on the surface forgot to turn off her bailout valve before removing her mouthpiece. Water entered the scrubber and when she replaced the mouthpiece and breathed from the unit she suffered a 'caustic cocktail'. |
| Trigger = Diver error (equipment-related) |
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• A diver forgot to open his tank valve before jumping in. Being negatively buoyant, he sank without an available air supply. |
| Trigger = Diver error (gas supply-related) |
| DISABLING AGENTS |
| Gas supply-related: |
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• A diver became entangled in a line inside a wreck, was unable to free herself and ran out of air. |
| Predisposing = Activity-related (wreck penetration) |
| Trigger = Environmental (entanglement) |
| Disabling agent: Gas supply-related (out of gas) |
| Ascent-related: |
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• A preoccupied underwater photographer failed to check his air, ran out of air, held his breath during ascent and suffered a pulmonary barotrauma. |
| Trigger = Gas-supply-related (out of air) |
| Disabling agent: Ascent-related (breath-holding) |
| Medical-related: |
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• Faulty oxygen sensors in a rebreather enabled the PO₂ to rise sufficiently to cause a hyperoxic convulsion in the diver. |
| Predisposing = Equipment fault (old/poorly-calibrated oxygen sensors) |
| Trigger = Gas supply-related (incorrect breathing gas mix from sensor failure) |
| Disabling agent: Medical-related (hyperoxic convulsion) |
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• A diver with a history of epilepsy is seen to become unconscious and have a seizure during a shallow air dive. |
| Predisposing = Health-related (epilepsy) |
| Trigger = Environmental (sensory effects) |
| Disabling agent: Medically-related (seizure) |
| Buoyancy-related: |
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• A diver surfaced in rough conditions after losing a fin due to a broken fin strap. He was negatively buoyant, failed to replace his regulator, inflate his BCD or ditch weights and was swamped by a wave and sank. |
| Trigger = Equipment-related (torn fin strap) |
| Disabling agent: Buoyancy-related (lack of buoyancy on surface) |
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• A drysuit inflator stuck open causing over-inflation and inversion in the water. During the process, the diver aspirated some water and became unconscious. |
| Trigger = Equipment-related (drysuit inflator malfunction) |
| Disabling agent: Buoyancy-related (inversion underwater) |
| Environment-related: |
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• A diver lost control of her buoyancy, ascended into and became entangled in the shotline and subsequently ran out of air. |
| Trigger = Buoyancy-related (poor buoyancy control) |
| Disabling agent: Environment - entrapment (out of air) |
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• A diver in rough water was thrown against rocks by a large wave, hit his head and became unconscious. |
| Trigger = Environmental (rough conditions) |
| Disabling agent: Environmental (head impact with rocks) |
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• An abalone diver was approached and subsequently attacked by a shark. |
| Predisposing = Activity-related (collecting seafood) |
| Trigger = Environmental (aggressive shark) |
| Disabling agent: Environmental – shark attack |
| Equipment-related: |
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• A rebreather diver on the surface momentarily forgot to turn off her bailout valve before removing her mouthpiece, enabling water ingress. The water entered the scrubber and when she replaced the mouthpiece and breathed from the unit she suffered a 'caustic cocktail'. |
| Trigger = Diver error (equipment-related) |
| Disabling agent: Equipment-related ('caustic cocktail') |
