Scuba diving has long been viewed as a sport for the adventurous and those willing to risk their life for a view of a world rarely seen by others. In reality, scuba diving is a safe sport primarily due to the principles of poka-yoke and Jidoka.
The Diver’s Alert Network (DAN) reports that one out of every 211,864 dives results in fatality. In perspective: one out of every 5,555 drivers in the U.S. die in car accidents; one out of every 7,692 pregnant women die from complications; one out of every 116,666 skydives result in death; and one out of every 126,626 marathon runners die of sudden heart attacks (Gibb, 2019). The top three reasons for diver fatalities according to DAN are pre-existing disease or pathology; poor buoyancy control; and rapid ascent.
Just as in business processes, preparing for and dealing with potential problems, is the key to keeping scuba diving a safe adventure. Safety begins with poka-yoke, Japanese slang for mistake-proofing or avoiding inadvertent errors. (Grout and Toussaint, 2009). Scuba diving preparation begins with training, but it can’t stop there. Gibb (2019) said, “divers who treat their scuba training as a “do it once and be done” course and fail to review dive theory and practice basic scuba skills after periods of diving inactivity are more at risk of a diving injury that divers who keep their skills current.” Grout and Toussaint (200) divide mistake-proofing into categories of mistake-prevention, mistake detection, preventing the influence of mistakes, and mistake-proofing in the work environment. Jessica Macdonald’s (2014) ten rules for safe scuba diving applied using poka-yoke strategies makes scuba diving look like this:
- Never ever hold your breath (the number one rule of scuba)
- Practice safe (and slow) ascents
- Stay physically fit (diving is deceptively physically demanding from entry and exit in the water, currents, carrying gear, and exposure to weather)
- Apply the Rule of Thirds to air-supply management (use 1/3 of air on the outward dive journey; 1/3 for the return and keep 1/3 as a safety reserve)
- Practice vital skills
- Establish positive buoyancy at the surface
Mistake Detection(alerts that a mistake has occurred)
- Most dive companies either recommend or provide dive computers in addition to the standard depth and air gauges on a diver’s buoyance compensator vest/wing.These tools not only guide a dive, but alert diver’s to mistakes such as an ascent that is too fast.
Preventing the Influence of Mistakes(mitigate results of errors)
- Dive within your limits
- Cancel or change a dive if the conditions are unsafe
- Don’t dive beyond qualification level (the basic open water scuba diving certification is to 60 feed and do not include wreck penetration or diving with enriched air)
Mistake-Proofing the Work Environment(reducing clutter, confusion, and ambiguity)
- Check your gear
- Annual dive equipment maintenance
- Pre-dive safety check with dive buddy
- Plan your dive; dive your plan
- Use the buddy system (don’t dive alone. Statistically, in 86% of fatal cases, the diver was alone when they died)
By following the guidance of poka-yoke, procedural mistake-proofing in scuba diving creates habits that result in desired outcomes (Grout and Toussaint (2009). Training and mistake-proofing are a primary reason scuba diving is considered safer than driving a car, jumping out of a perfectly good airplane, having a baby, and even running a marathon.
However, there are the inevitable unknowns that arise when diving whether it is overwhelming nerves on the boat prior to entering the water, a mistake that leads to a diver running out of air, a random run-in with nature that results in an injury, or a buoyancy issue that causes a rapid ascent. No amount of planning and training can prevent all issues. There are so many unknowns in the ocean that preparation alone is not the only tool that keeps scuba divers safe. Jidoka is the “practice of stopping the process when a problem occurs” (Grout and Toussaint, 2009). There are five steps to Jidoka and when applied to scuba diving they look like the following:
Detect the Problem
- According to Grout and Toussaint (2009), there are a “spectrum of methods for stopping processes ranging from warnings in the work environment to mechanical devices designed to stop processes and empower humans to stop the process.” In the same way this applies to a Toyota assembly line, scuba diving has its own methods for stopping processes. From the pre-dive buddy check to mechanical tracking and warnings on a dive computer, there are a number of ways astute divers can learn about issues before they become life threatening. One example is ascending after a 35-minute dive to 100 feet. If a diver is ascending too fast he risks nitrogen forming bubbles in the body, a condition that can result in decompression sickness or the “bends”. A dive computer will actually give a noise alarm if this is happening
Stop the Process
- “A good rule of thumb is: if in doubt, stop.” (Grout & Toussaint, 2009). Anyone can abort a dive when issues arise – the divemaster, dive instructor, a dive buddy, etc. Halting the dive can happen in the early morning if the weather is too rough to be in the ocean, on the boat prior to entering the water if the buddy check results in an issue with equipment, mid-dive if there are issues with air or buoyancy, etc. As Grout and Toussaint (2009) explain, “each worker at Toyota is empowered to stop the assembly line.” It is the same in diving.
- One of the biggest mistakes divers make is earning their dive certification and then diving once or twice a year without revisiting the skills they learned in that first open water course. While technical dive skills have changed little over the years, buoyancy control and comfort in the water are mastered through time in the water. Taking a refresher dive course prior to each dive trip is a smart way to restore the process of diving to proper function and prevent issues. The best thing to do is simply dive year-round. Even in land-locked and cold Colorado, divers can practice in the 15-foot swimming pool in Fort Collins every Wednesday night throughout the year. Divers also hone their skills in high-mountain lakes in the summer months (nothing like the murky waters of Horsetooth Reservoir to learn underwater navigation).
Investigate the Root Cause of the Problem
- One example in scuba diving is the diver who is often the first to run out of air. He should investigate what is causing the depletion of air at a quicker rate than his fellow divers. According to the Diver’s Alert Network (DAN) some of the most common causes of air depletion include:
- Diving too deep (gas consumption increases dramatically with depth)
- Staying too long (all divers should return to the boat or shore with 1/3 of their starting air supply in reserves).
- Working too hard (fighting a strong current, lack of buoyancy control or an exertion can speed up air consumption)
- No monitoring pressure gauges and monitoring air supply.
- Anxiety (being anxious causes divers to breath quickly and deplete tank reserves faster than vigorous exercise)
- Starting with a less than full tank (should be identified on a pre-dive buddy check)
- Not opening the tank valve all the way (also identified on a pre-dive buddy check – see above for the processes of poka-yoke)
- Frequent depth changes and using the BCD (buoyancy compensator device) to move up and down in the water rather than using your natural buoyancy compensators … i.e. lungs.
- Equipment issues
- There are a number of ways scuba divers install countermeasures including the use of dive computers, systematic and consistent training, and following the rules of diving including planning dives and diving the plan. Perhaps the biggest countermeasure in diving is diving with a buddy. As stated above, 86% of fatalities happen when divers are exploring alone. Having a trusted buddy and working the systems of buddy checks, planning, and communicating under the water makes this adventure relatively safe.
Approximately five percent of the ocean world has been discovered and the pull for exploring its unique landscape and creatures draws a little over one percent of people in the U.S. to scuba diving. By following the rules of poka-yoke and Jidoka, scuba divers can safely explore the seas. “For divers who approach diving with an attitude of respect and conservatism, the risks of diving are minimal,” (Gibb, 2019).
13 Ways to Run Out of Air & How Not To, www.diversalertnetwork.org/health/SmartGuide-Air/index.html.
Gibb, Natalie. (2019) “Can You Die from Scuba Diving?” LiveAbout, www.liveabout.com/is-scuba-diving-safe-or-dangerous-2963049.
Grout, J. and Toussaint, J. (2009). Mistake-Proofing Healthcare: Why Stopping Processes May be a Good Start. Business Horizons, 53(2), pp. 149-157.
Macdonald, J. (2014). “Ten Rules For Safe Scuba Diving.” Scuba Diver Life, 9 Dec. 2017, scubadiverlife.com/ten-rules-safe-scuba-diving/.