Dive instructors are taught to stress the importance of constantly monitoring the submersible pressure gauge and returning to the boat or the dive exit point with at least 50 bars remaining in the tank. In all beginners' training programs, divers learn the best way to avoid an out-of-air emergency is to never run out of air. While this technique is absolutely correct, divers should be trained and prepared to cope with an out of air situation since Prevention is only half the answer.
Out-of-air emergencies may well be one of the most common emergency events in sport diving. Do not underestimate it - divers do run out of air.
Why do divers run out of air? There are several causes but it comes down to this: Divers are not perfect.
Diver fault is responsible for an estimated 99% of all out of air events. Distraction, overloading and miscalculation are the main three causes of out-of-air incidents.
Distraction is perhaps the major cause of out-of-air events. In fact, it is considered as a deadly killer because it catches the diver by surprise and increases the risk of panic. Divers often become fascinated by the beautiful undersea world, lose track of time and simply forget to look at their tank pressure.
Overloading is a less frequent cause of out-of-air incidents. Excess equipment, accessories or a bulky underwater camera housing can be a start. In addition, divers can encounter heavy objects they try to drag to the dive boat or the beach. These collectibles include such items as: lost weight belt(s), or a lost anchor! Additional weight and excess drag can burn up air/gas supply in half the normal time.
Miscalculation in my personal opinion is the greatest cause of out-of-air events. It is virtually impossible for a diver to precisely plan a dive he/she has never made before. He/she may encounter strong currents, go deeper than intended, have an over-weighted belt, or fail to take the shortest way back. Any combination of these factors can contribute to a miscalculation of air consumption and therefore result in the sudden termination of the dive plan.
When a diver runs out of air, he/she has a margin of approximately 15-20 seconds to check equipment, (in case of a false alarm), make an accurate evaluation of the situation, and finally make the appropriate decision.
Controlled Emergency Swimming Ascent. This will not allow the luxury of a safety stop or a required decompression stop. So if you are not thrilled by the idea of a solo ascent from deeper depths, you should take all necessary measures to prevent running out-of-air.
Most experts agree that the chances of screw-ups are dramatically reduced if you can solve a problem yourself. However, CESA is one of the most controversial self rescue methods used today. The inherent risk of air embolism puts the method in hot debate. Therefore, many modifications have been introduced to the method over the years.
Today divers are taught to retain the regulator in the mouth while swimming slowly upwards towards the surface. It is my personal opinion that it is desirable to make a direct ascent to the surface under your own power, keeping the regulator in your mouth and continuously exhaling slowly. Students are always astonished how long they can slowly exhale even when saying a continuous ‘Aaaaah’, sound all the way up to the surface.
I often tell my students during the exercise briefing that each one of them would feel he/she is one of the greatest opera sopranos of the world! In addition, you will probably get a couple of breaths on the way up as the ambient pressure on the hoses is reduced during the ascent.
Although most training agencies today agree that the advantages of CESA far outweigh the risks, most divers are so well conditioned to seek help from their buddy underwater even if they run out of air even and are only a few meters deep! The obvious solution never occurs to them.
Independent Backup Reserves. The use of pony bottles or a ‘Spare Air’ are perhaps a safer, more dependable alternative since they allow you to make an entirely independent self rescue. The disadvantages can be summarized in three main points:
Octopus Ascent is today considered the most desirable option for air sharing in any out-of-air situation. It is a quick, simple and easy method of sharing air with your dive buddy while making a normal ascent to the surface. However, octopus ascents require the help of a dive buddy who not only has to be within reach in the proper time, but also has sufficient air supply to support the two divers.
Buddy Breathing is so far down in the list of preferences that it has been relegated to a vanishing art. However, given no other alternatives, it can get you back to the surface if both divers are skilled in its practice. Unfortunately, the record of double fatalities for divers engaged in buddy breathing is relatively high. The reality is that the skill is difficult to master for most student divers and then quickly lost unless practiced often in the field.
Buoyant Ascent is probably the most uncommon and most forgotten way of self rescue, often ignored when should be done and unfortunately practiced when it should not! Although it is not intended here to go into the details of the technique, it is clear that alot of training and practice are the only way to master such a skill. One can summarize the technique as follows:
Taking off the weight belt at depth allows a quick start of the ascent, letting the expanding air out from your BCD and flaring your body to a horizontal position are two ways to slow done the ascent rate as needed. Looking up to see the water surface (if you are in the clear Red Sea), and exhaling all the way up are ways to prevent lung overexpansion.
Which method is best to cope with an out-of-air situation? Honestly, there is no such thing as the "best method" for self rescue. Each has been time tested and proven to save lives. Each offer advantages under certain circumstances.
The important issue is that every diver should be responsible, and take all measures to prevent an out-of-air incident. Nevertheless, every diver should be fully trained and proficient in all self rescue methods available.
We should not argue about the theoretical advantages of one method over another, this would not help solving the problem when it comes. I believe that the more you know the better chances you have.
If you did not obtain training (during your basic class) in all available methods of self rescue, you better learn about them now. This is especially true if you are not aware of the latest techniques of my personal favourite one: Controlled Emergency Swimming Ascent (CESA). Remember that you can achieve safety through education. So when you are down there facing a situation, take a second to work out the "best method".
Safe diving.
By: Zeyad M. El Bassel
NAUI Course Director
