Investigation of diving accidents


Investigation of diving accidents includes investigations into the causes of reportable incidents in professional diving and recreational diving accidents, usually when there is a fatality or litigation for gross negligence.
An investigation of some kind usually follows a fatal diving accident, or one in which litigation is expected. There may be several investigations with different agendas. If police are involved, they generally look for evidence of a crime. In the U.S., the United States Coast Guard will usually investigate if there is a death when diving from a vessel in coastal waters. Health and safety administration officials may investigate when the diver was injured or killed at work. When a death occurs during an organised recreational activity, the certification agency's insurers will usually send an investigator to look into possible liability issues. The investigation may occur almost immediately to some considerable time after the event. In most cases the body will have been recovered and resuscitation attempted, and in this process equipment is usually removed and may be damaged or lost, or the evidence compromised by handling. Witnesses may have dispersed, and equipment is often mishandled by the investigating authorities if they are unfamiliar with the equipment and store it improperly, which can destroy evidence and compromise findings.
Recreational diving accidents are usually relatively uncomplicated, but accidents involving an extended range environment or specialised equipment may require expertise beyond the experience of any one investigator. This is a particular issue when rebreather equipment is involved. Investigators who are not familiar with complex equipment may not know enough about the equipment to understand that they do not know enough.
For every incident in which someone is injured or killed, it has been estimated that a relatively large number of "near miss" incidents occur, which the diver manages well enough to avoid harm. Ideally these will be recorded, analysed for cause, reported, and the results made public, so that similar incidents can be avoided in the future.

Reasons for investigation

Professional diving accidents are usually investigated when a reportable injury occurs in terms of occupational health and safety legislation. The purpose is generally to allow avoidance of recurrences of the circumstances leading to the incident if practicable, and where relevant, to establish whether there was fault attributable to any involved party, which could lead to criminal or civil charges.
Accident investigation may help to identify the cause of a specific accident. If a pattern can be identified this may inform procedures and legislation to reduce the risk of the same pattern of accident recurring in the future. An investigation may identify shortcomings in training or procedures, or problems with equipment. Fatalities are often investigated as potential crimes until the cause of death has been identified. Insurance claims may rely on information from an investigation to establish whether the accident is covered by a policy. Occupational health and safety inspectors may investigate an occupational diving incident to identify whether regulations have been violated. Civil litigation for claimed damages can be more equitably decided when the circumstances leading to the injury have been identified. The ability to provide documentary evidence showing that correct procedure was followed can simplify the investigation and may lead to more accurate and reliable findings.
Equipment, procedures, organization, environment, individual factors and interactions between them are the sources of contributing and compounding events and conditions. Analysis of near accidents can be of great value to identify sources of error and allow planning to reduce or eliminate contributing and compounding conditions. A safety study estimated about a million shortcuts taken per fatal accident.
Accident investigations typically focus on the end event, and attempt to erect barriers to similar accidents, such as personal protection equipment, backup equipment or alarm systems. These are intended to prevent the recurrence of similar accidents, and are often effective in this limited goal. Accidents continue to occur because the majority of the contributing and compounding factors are not addressed. Human behavior and the systems in which people work are too complex to analyse all possible interactions. A more effective route to accident prevention is to reduce or mitigate the occurrence of human error by focusing on the contributing and compounding human factors that create an environment in which accidents are likely to occur.

General procedures

The victims of diving accidents are generally recovered or rescued by other divers in the vicinity. It is unusual for a diver to be left underwater with no immediate attempt at recovery, so in situ forensic investigation is seldom applicable, and the investigation usually relies on the accounts of witnesses. Different people may make different reports and develop different opinions about what happened. It is not unusual for people with less knowledge and understanding to misinterpret what they have seen and investigators need to gather as much information as reasonably possible to improve the chance of getting accurate information.
Recommended autopsy procedures have been summarised by specialists in diving fatality investigations and are available as guidelines to reduce the risk of overlooking pertinent evidence by pathologists less experienced in diving related autopsies.
There are three parts to a fatal accident investigation.
  • Autopsy to determine where possible any medical factors that may have caused or contributed towards the death,
  • Investigation of the sequence of events to determine whether any procedural or behavioural issues caused or contributed towards the death. This is usually done through witness interviews and looking into the deceased's history of training and experience, and
  • Inspection and testing of the equipment used by the deceased, to find out if any equipment problems, defects, or malfunctions were contributory.
Most marine incident emergency response and accident investigation protocols have been written to manage surface incidents. These protocols are often inadequate for discovering the facts that could improve diving safety, and there is often a lack of cooperation between investigators and stakeholders in the outcomes of investigations.
It is not usually necessary to dive to inspect the site of a diving accident, but sometimes there are unusual environmental features which make underwater inspection desirable.

Recreational diving accidents

A large proportion of recreational divers use a personal decompression computer to monitor depth, time and decompression status. These generally log a dive profile by recording depth and time at regular intervals, and this data can usually be downloaded or inspected on the instrument. This usually constitutes a reliable and objective record of the actual dive profile, and is normally admissible as evidence. Accuracy may vary depending on calibration. In some cases assistance from the factory may be needed to recover the data. Similar, often more detailed information may be recorded by the electronic control system of a rebreather.
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Professional diving accidents

There will generally be regulatory requirements regarding both the performance and record keeping for a professional dive, and these may vary in detail depending on the jurisdiction. Where diving falls under occupational health and safety legislation any accident occurring at work may be investigated by the responsible OHS organisation, and if criminal activity is suspected, also by the police. The regulations will probably require a documentary record of the risk assessment associated with the dive, a documented dive plan for the specific dive, an operations manual specifying the accepted equipment and procedures, checklists for preparation and pre-dive checks, and a record of the timeline and depths of the diving operation in the diving operations log. All of these may be considered legal documents and evidence, but there is no guarantee that they will have been followed, and this should be checked by looking for corroborative evidence. In some jurisdictions, some forms of professional diving may be covered by different regulations, exemptions or conditional exemptions.
Professional diving on scuba also frequently uses dive computers as dive profile recorders. The data logged by the computer can be useful in determining the details of the dive profile and interpreting the sequence of events, particularly where there is no communications recording available. Similar, often more detailed information may be recorded by the electronic control system of a rebreather.

Commercial diving accidents

Surface supplied diving usually uses a diver intercom system to provide voice communications between the diver and supervisor, both for management and control of the dive, and for safety, as the supervisor can monitor the condition of the diver by hearing the breathing sounds. It is standard procedure for many contractors to record the voice communications of the dive and retain them for at least 24 hours, or longer in the case of an incident. These recordings are usually available as evidence in an official investigation. Surface supplied divers do not generally carry personal decompression computers, as depth profile is monitored from the surface, and decompression is controlled by the supervisor, who will log changes in depth as and when they occur.

Preservation and disclosure of evidence

Failure to identify, preserve, and produce critical evidence such as dive computer data can result in sanctions against the responsible party, including findings in favour of the party requesting the lost information. Investigators without a sufficient knowledge of diving equipment have been known to destroy or lose critical evidence through mishandling of equipment, even when it survived rescue and recovery efforts.
In US Federal law the owner of equipment that logs data during an incident that may be the subject of litigation is obliged to preserve that data and make it available as evidence if the case comes to court at a later date. Litigants are required to find out what they have and disclose everything relevant to the opposition.
Detailed checklists and standardised report formats have been developed for use by investigators to minimise the risk of missing important evidence and of compromising the evidence. These are available for open-circuit and rebreather equipment.