Accident Analysis and the Birth of Modern Cave Diving
Cave Diving Training in Mexico’s UnderGround river systems
How Learning From Our Mistakes Has Made Cave Diving Safer
Although cave diving has become increasingly popular over the last decade, it is still considered exceptionally risky by many divers. While accidents involving scuba divers in caves do occur, a great number of them involve divers who are untrained in the activity. When performed according to safe diving guidelines, cave diving has a surprisingly low accident rate. So how do trained cave divers stay safe in caves?
One answer is that they analyze the mistakes of others and create guidelines to avoid similar accidents in the future. This process is known as accident analysis and is one of the reasons that cave diving has evolved into a much safer sport than many divers realize.
Cave Diving Was Not Always as Safe as It Is Today
Until the 1980’s, cave diving was a niche activity, and the number of fatalities was preoccupying. From the beginning of the sport in the 1950’s until the appearance of the first specific set of rules for cave diving in the 1970’s, more than four hundred divers died in Florida.
In 1974, twenty-six divers died in Florida caves alone.
The Birth of Accident Analysis
In 1979, Sheck Exley published the now famous “Basic Cave Diving – A Blueprint for Survival.” For the first time, accident analysis was used as a tool to understand the causes of past fatalities and incidents in order to create a set of rules and safety protocols that work in real-life situations.
Exley discovered that three major factors led to the diver’s demise in most cave diving accidents.
Two additional contributing factors were later identified. Examining these factors lead to the development of what are now known as the five rules of accident analysis. These five guidelines are still taught in cave courses today, and in combination with rigorous training have greatly increased cave diver safety.
The Five Rules of Accident Analysis for Cave Diving
1. Seek Proper Training and Dive Within the Limits of Your Training
Nine out of ten cave diving fatalities involve divers with no formal cave diving training. A large share of these fatalities are diving professionals — open water instructors and the like — who apparently felt that their high level of training was enough to dive in any environment.
An diver who ventures into a cave without cave training simply does not know what he does not know. Without formal training, a diver in a cave may be unaware of the importance of a guideline or respecting the gas management rule of thirds. Some divers without formal cave training may have researched safety protocols online and think that this basic knowledge is sufficient to dive safely. No article or manual can safely teach a person to cave dive. In-water practice under the supervision of a qualified instructor is the only way to perfect safe cave diving skills.
2. Maintain a Continuous Guideline to the Open Water
Cave divers should always follow (or place) a continuous guideline to the surface. Without a continuous guideline to follow out from the deepest point of penetration, a diver in a zero visibility situation will have almost no chance of finding his way to the entrance. Even with perfect visibility, it can be surprisingly easy to get lost in a cave. The complexity of many cave systems is such that a diver will have difficulty navigating out by memory alone.
Following a line in zero visibility, and even laying a guideline in a first place, are technical skills that require long practice sessions in order to master. Again, watching a video or reading an article will not will not adequately prepare a diver to perform this skill in real life.
3. Reserve Two-Thirds of Breathing Gas for the Exit
This is commonly called the gas management rule of thirds. A cave diver reserves two-thirds of his starting gas for the exit in order to have sufficient gas if his exit is delayed. Problems that could create delayed exits include getting entangled in the guideline, becoming stuck in a restriction, or making an exit in zero visibility. Following the rule of thirds also ensures that a diver will have sufficient gas to share with his buddy in the unlikely event that his buddy runs out of breathing gas.
A good cave course will teach divers that reserving two-thirds of the gas supply for the exit is an absolute minimum. Even two-thirds of the starting gas may be insufficient for dives involving unknown caves, unfamiliar equipment, complex navigation, restricted passageways, or downstream flow.
4. Never Exceed the Maximal Operation Depth of Your Breathing Gas
A large number of cave diving fatalities are related to diving below the maximum operational depth (MOD) of a diver’s breathing gas and experiencing severe narcosis or oxygen toxicity.
It is critical that a cave diver maintains a clear head. When experiencing narcosis, a diver’s reaction time becomes much longer and his analyzing capacity reduces dramatically. This may lead him to make poor decisions. A small problem can lead to a catastrophic chain of events if the diver’s reaction is tempered by narcosis. A general rule is that air shouldn’t be used any deeper than 100 feet (30 meters) to avoid the negative effects of narcosis.
In addition, divers should personally analyze their breathing gas mixtures before every dive, and should never exceed a partial pressure of oxygen of 1.4 ATA to avoid oxygen toxicity, which can cause convulsions and loss of consciousness.
For this reason, many cave dives deeper than 100 feet (30 meters) are made using trimix.
5. Use Complete, Functioning and Appropriate Equipment
This rule originally stated that a diver should carry minimum of three mechanical dive lights. In recent times, the rule has been expanded to state divers should use equipment that is functional and appropriate for the dive plan.
Cave divers should be sure to have adequate redundancy of all vital life support equipment, but should not bring excessive gear on the dive. Cave diving gear should be well maintained, and replaced with no hesitation when worn out. Chose cave diving equipment for its quality, durability and practical features, and remember: Chose your equipment as if your life depends on it, because it does!
The Take-Home Message About Accident Analysis and Cave Diving
Cave diving is a sport with inherent risk. However, with proper training and procedures, a cave diver can greatly reduce the risk of venturing into underwater caves. Accident analysis is an continuing practice that examines the causes of cave diving accidents and develops rules to avoid repeating mistakes. Cave diving has evolved into a widely-practiced form of diving with a good safety record (considering the risks involved), largely due to the practice of accident analysis and methodical, systematic training which teaches the rules of accident analysis to prospective cave divers.