When people come to dive with us at Davy Jones Locker most of them have some awareness about safety. They may not understand specifics but there is an understanding that there are procedures that are followed to reduce risk. It’s only after starting training that many people become aware of the risk of altitude and flying after diving. This is something that is especially significant when teaching courses on Koh Tao.
Tourists on a tight schedule may plan to take a course and then fly from Samui. Because of a lack of understanding about altitude this may only be a few hours after completing their dives. As a result we encourage customers to stay for at least 1 night after completing their courses. It gives them a chance to relax and avoid the potential risks of flying after diving.
DJL diving instructor Matt goes into more detail about the precautions that divers need to take. He also explains the guidelines that divers should follow.
Flying After Diving
One of the most important guidelines taught in any open-water course is the danger of going to altitude too quickly after diving. The most common way for this to occur on Koh Tao is flying after diving. But divers often have questions about specific recommendations because the rules occasionally change. At DAN (Divers Alert Network) the relationship between diving and altitude is something they have been studying for 20 years. This helps to generate data and keeps the “diving to flying” guidelines taught by training agencies up to date. Below is a list of three of the most common altitude and diving questions.
Can I dive immediately after flying?
Decompression issues don’t occur as a direct result of diving after flying. This is because you have less inert gas in your tissues after flying than if you stay at ground level (unless you land at high altitude). Because of this there are no set guidelines for when to make your first dive. The critical issue is simple fitness to dive. Air travel can leave divers tired, hungry and maybe feeling a bit dehydrated. This can be coupled with an overall feeling of stress and disorganization. Long-distance travel compounds the problem, particularly when crossing multiple time zones. The more you or any member of your dive team are affected the longer the recovery time you need. This will need to be taken into consideration to build before starting to dive.
Incorporating pre-dive flight recovery time into your travel plans is a great way of combating any issues. Tiredness and a lack of organization can have a negative impact on performance and safety. If you are tired or not feeling 100% an emergency situation may prove more difficult than usual. So make sure you get plenty of rest and are ready.
Of course immediate diving can sometimes be feasible. For example if you are travelling on a shorter flight or have easy travel that has you arriving at your destination having eaten and rested properly with the recommended intake of fluids. This should only be undertaken however once you and your dive partners make a fair and objective assessment of your condition. Why compromise your safety because you or someone else is in a hurry to make the first dive? Something like this could this could ruin more than your whole trip.
What is a sufficient waiting period before flying after diving?
The dangers of travelling to altitude too quickly after diving are the same dangers diver expose themselves to when ascending too quickly from a dive. The scientific principles are the same in both sitautions. Going to altitude takes you to an area of lower outside pressure. This means that residual nitrogen still dissolved in your blood can come out of solution as bubbles. This occurs if the pressure reduction isn’t slow enough to allow your body to off-gas safely. Remaining at ground level for a period of time before reaching altitude serves the same purpose as a decompression stop. There will be more residual nitrogen in your system after deeper, longer dives. Consequently the surface interval before flying will need to be longer. The required waiting time should relate directly to the pattern of diving completed.
The general recommendation before flying is to follow the general practice of allowing a surface interval of 24 hours or more after diving. This is enough of an interval to give peace of mind will also provide a buffer for unexpected problems like a loss of cabin pressure during flight. It is always better safe than sorry and almost every location has enough to entertain you for the final day. Alternatively you can choose to follow the minimum guidelines established by DAN and the Undersea and Hyperbaric Medical Society for flying in commercial pressurized aircraft.
A single dive within the no-decompression limits: 12 hours
Repetitive dives of multiple days of diving: 18 hours
Decompression dives (planned or unplanned): substantially greater than 18 hours
UHMS-DAN guidelines have their basis on reasonable laboratory data for the no-decompression exposures. The lack of clarity regarding the post-decompression dive recommendation was an acknowledgement definite guidelines were difficult to establish due to a lack of sufficient data. This brings us back to the 24 hour guideline. A good way to stay out of trouble is to plan conservatively. Given the variety of decompression algorithms now available for divers a healthy buffer is a good way of giving yourself an extra form of insurance. Divers who don’t suffer any DCS symptoms during a trip should also abide by these guidelines. Divers will need to undergo a medical evaltuation if they experience DCS symptoms during a dive trip. Ideally the evaluation will need to take place before flying. You can contact DAN to help connect you with appropriate resources or in case of emergency.
An important guideline is not to “push the tables” in terms of depth and bottom times. In this respect it is also a wise choice not to push the guidelines regarding the surface interval for flying after diving. It is a good idea to be more conservative with your final dives and also to leave enough of a buffer between your last dive and your flight home. This is all is part of smart dive planning which is a goal for all in the community.
No plane, no problem — right?
Wrong. Travelling to altitude is a problem, regardless of whether you get there by plane or go up a mountain. Many destinations offer more than just diving which means you could be active above and below the water. An example of this is Hawaii where you can dive in the morning and spend the afternoon trekking in the mountains and volcanoes. Significant altitude is any form can pose a problem and divers need to be aware of this.
For aircraft travel the cabin pressure is usually the equivalent of between 6,000 and 8,000 feet regardless of the cruising altitude of the plane. Consequently hiking 10,00 feet up a mountain is potentially more dangerous than flying in a pressurized aircraft.
Another example is if you are travelling home by car. If your journey takes you through a mountain range this could also pose a risk. Knowing that you have to drive through a mountainous area, or any area that could see a significant increase in altitude, should mean accounting for any altitude change in your overall plan.
Exposure to altitude is potentially dangerous. There is no dodging the considerations required and ignoring potential dangers can result in severe injury. So remember to keep your feet on the ground after you dive, if only for a little while.