Why can’t you fly after diving?
Why shouldn’t you fly after diving? This is a question we get asked a lot. Any certified diver should know the answer to it. During your Open Water Diver Course, you learn that reviewing important knowledge and refreshing your memory, is part of the standard safety procedure. Therefore this blog is not only for beginner divers, but for the more experienced divers as well.
Planning a dive requires extensive preparation, as well as implementing various safety measures in advance. During the Open Water course, this process is covered repeatedly in both theory and practice. Important to know for both beginner as well as experienced divers, is to be aware of the fact that the safety measures are not only in place before and during a dive, but also extend to a period of time after the dive.
People often ask this question: when is flying safe? Why shouldn’t you fly after diving? Can I fly on Saturday if I book a dive on Friday? Can I fly in the afternoon if I dive in the morning? When is flying safe? Depending on where you get your information, there are many answers to these questions. So perhaps the right question is:
Why is it not a good idea to dive first and fly afterwards?
To answer this question correctly, you first must understand what happens to your body when you scuba dive. When you scuba dive, you will experience pressure of the water surrounding you. At the surface, at sea level, we experience 1 bar pressure from the atmosphere around us. Every 10 meters we descend under the water, 1 bar of pressure is added. So at 10 meters depth, we experience 2 bars pressure. At 30 meters depth, we have 4 bars pressure etc. This pressure will affect your body.
The effects of pressure on your body during scuba diving
So, what does this pressure do to your body? The air we breathe consists of oxygen and nitrogen. Our body does not use nitrogen. At the surface, it is easy for our body to dissolve the unused nitrogen. However, under the water this is not as easy. Because our body is under pressure, it starts to absorb the nitrogen. The nitrogen forms small bubbles in our veins. This is harmless. When we return to the surface, the surrounding pressure drops back to 1 bar, and our body will again be able to dissolve the nitrogen in our bloodstream. The deeper you dive, the faster your body absorbs in the nitrogen. The longer you stay at depth, the more nitrogen your body absorbs.
It is very important to ascent slowly during the end of your dive. But why is that?? To make you understand, picture yourself a bottle of cola. If you shake the bottle and open the cap to fast, the cola will force itself out of the bottle and leave a big mess. But if you open the cap very carefully, and let the pressure release very slow, nothing will happen and the cola will stay inside the bottle without spilling a drop. Now, when you leave the bottle without the cap on it, after a while the bubbles will disappear from the cola.
The same principle can be applied to your body regarding nitrogen: when we ascent slowly, the surrounding pressure decreases slowly, allowing the nitrogen to dissolve gently and safely without harming our bodies. Do we shoot up to the surface after a dive? Then the nitrogen doesn’t have time to dissolve at a slow rate causing the small bubbles to form big bubbles. And this is what causes the trouble: big air bubbles traveling through your bloodstream. Trying to find a way out or ending up in places you do not want. This is what we call decompression sickness.
After a dive, it takes our body some time to dissolve all the nitrogen. To be exact: after 1 dive it takes 12 hours, after 2 dives it takes 18 hours and after 3 or more dives, it takes 24 hours.
Pressure at high altitude
You now know what the effect of pressure is while you are scuba diving. However, to answer the main question, we also need to understand the effect of pressure above the water. And especially the pressure at (high) altitude.
The higher you go, the thinner the air gets and the lower the pressure becomes. Picture a high mountain. The air on top of the mountain is not the same as the air at sea level: it is thinner and the pressure is lower. During a hike or a mountain climb, people often need time at a certain hight to get adjusted to the air they are beathing. The air is so thin they get exhausted easily or even get sick.
Altitude diving – a specialty course
The effect of this lower pressure on the body also has a great influence on divers. Every dive at a hight higher than 300 meters, is considered a high altitude dive. Diving at altitude comes with different dive tables and restrictions. This has to do with the different intake of oxygen and nitrogen in the body. Are you planning on diving at an altitude of 300 meters or higher? Then book the course of altitude diver so that you are well aware of what you are doing and you can dive safely.
Pressure while flying
You now understand that the higher you go, the lower the pressure becomes. An airplane cruises at an average hight of 10 kilometres. The pressure at this altitude is too low for us. Therefore, during the flight, the pressure inside the cabin is stabilized. The pressure inside the cabin, is comparable to the pressure at a hight of 2.400 meters (think of the pressure in the mountains).
The answer to the question: why can’t I fly after diving?
The answer to the question ‘why can’t I fly after diving’ is actually pretty short: residual nitrogen.
Ofcourse we will summarize the answer for you to make sure you understand.
You are not allowed to fly after diving because your body still has residual nitrogen. To process and eliminate all the nitrogen safely, you descent very slowly after each dive. At the surface, the surrounding pressure is 1 bar. Your body will need about 12 to 24 hours to get rid of all the excess nitrogen from the dive.
If you surface to fast at the end of a dive, there is too much difference between the pressure under the water and on the surface. The small nitrogen bubbles in your body, will form bigger bubbles that your body is not able to process. The bubble will try to find a way out through your tissues and the big bubbles can cause blockages anywhere in your body: decompression sickness.
The higher you go, the lower the surrounding pressure gets. The lower the pressure gets, the faster the bubbles will form and fight a way out.
So, what will happen if you enter an airplane with residual nitrogen in your body? You will rapidly increase to a hight with a very low pressure surrounding you. Your body does not have time to adjust and dissolve the nitrogen in a safe way which will result in a high risk of decompression sickness.
Can I travel through the mountains after diving?
We briefly spoke about altitude diving. The important thing to remember here, is the limit of 300 meters. From this hight up, you must consider the effects of the lower surrounding pressure and the residual nitrogen in your body.
Have you just been diving, and plan a hike through the mountains? Or are you traveling and plan on moving to the next stop, using a mountain road? Make sure there is enough time between your last dive and your planned hike or journey.
How soon after diving can I fly?
By now, we all dive with a dive computer. This dive computer registers every dive, the depths and times. According to your personal dive profile, the dive computer calculates the residual nitrogen in your body and tells you when you are allowed to fly.
Sounds nice right? But what my computer doesn’t know, is how fit I am at that moment. Am I overweight? Am I of older age? Did I have a rough night etc. There are a lot of things that effect the absorption and processing of nitrogen by a body. Therefore, always stick to the following guide line to calculate the time between diving and flying:
After 1 dive no flying for 12 hours
After 2 dives no flying for 18 hours
After 3 or more dives no flying for 24 hours
Remember: with diving safety always comes first.
Risks of diving
Diving is no longer seen as an extreme sport. Both children and people at higher age can enjoy it. Also, is has been proven to be good for your health. That being said, diving is not without danger. While diving we explore a world that is not naturally ours. This is why we need dive equipment and training to be able to safely enjoy it.By the way, if you enjoy diving you should check a diving course hurghada.
Every piece of equipment and every training is developed with safety as a priority. Many people think that running out of air is the biggest danger when it comes to scuba diving. In reality, this is a pretty small risk. During each dive you constantly check your air consumption and reserves. You stay well within your limits and plan your dive so that you surface with more than enough air left for emergencies.
If we have to point out two risks of scuba diving, let’s talk about decompression sickness and lung trauma. Every diver is trained to avoid taking any risk regarding decompression sickness and lung trauma. Therefore they are pretty rare. Still we want to discuss these two risks, because we want you to be aware of them.
Decompression sickness (DCS)
Decompression sickness (DCS) is a serious condition that, in the worst case, can cause paralysation or even death. DCS is the consequence of nitrogen in the blood that the body wasn’t able to safely dissolve after a dive. This can occur after a rapid ascent form great depth or exceeding the hight limit of 300 meter straight after a dive. The nitrogen now forms bigger bubbles that travel through your bloodstream and saturate your tissues causing pain.
The risk of DCS does not apply to snorkelers. Snorkelers don’t dive to depths where their bodies experience sufficient pressure to absorb nitrogen.
To limit the risk of contracting DCS, divers should always follow the next three rules:
- Do not cross your bottom times. The deeper you dive, the more pressure your body experiences, the more and faster your body absorbs nitrogen. To stop your body from absorbing to much nitrogen at certain depths, every depth has a time limit you are allowed to stay. Do not exceed these limits.
- Do not fly after diving and stay below 300 meter after diving. If your body still contains residual nitrogen, your body needs time to dissolve this. If you travel to altitudes higher than 300 meters, you will risk contracting DCS due to the drop in the surrounding pressure.
- Ascent slowly after each and every single dive and always do a safety stop. A safety stop takes only 3 minutes at a depth of 5 meters. This safety stop gives your body extra time to dissolve the nitrogen that your body has built up during your dive.
The number one rule we teach you during the Open Water diver course in our scuba diving hurghada center, is to neve ever hold your breath while scuba diving. But do you understand why this is so important? Let me explain in a very simple way.
You already learned about the pressure under water: at 10 meters there is 2 bars pressure. At 20 meters there is 3 bars pressure and so on. Pressure results in things being pressed together. Picture yourself a balloon. You inflate the balloon and tie it so the air cannot escape. Now you take the balloon to a depth of 10 meters. What happens to the balloon?
At 10 meters, the pressure is 2 bars. This means the balloon is pressed together until 2 times smaller than its size at the surface.
Now let’s do it the other way around. We have a balloon at 10 meters depth, 2 bars pressure. We inflate it and tie it so the air cannot escape. Now we take it to the surface. What happens to the balloon? The balloon will grow to twice its size.
The effect of pressure on your lungs is exactly the same as the effect on the balloon. Only your lungs are not as flexible as the balloon, resulting in serious damage of your lungs. Therefore it is very important to always keep breathing during your dive. Especially during the descent and ascent. This way you can easily prevent lung trauma.
I think I have decompression sickness. What should I do?
If you think you have decompression sickness (DCS), the first thing you do is alert your buddy, dive instructor or dive guide. He or she will know what to do.
You lay down and start breathing 100% oxygen. The medical emergency services will be alerted and you will be taken to a decompression chamber as fast as possible. The decompression chamber is a chamber you can compare with a big tube. It has medical supplies and there is (not always) space for more than one person. You take place inside the chamber after which it is closed off. Then they will raise the pressure inside the chamber, similar to the pressure under the water during a dive.
During the treatment, the pressure will be reduced bit by bit. By doing this really slow, your body has the time to break down and dissolve the nitrogen that has been build up. One treatment can last for hours and more than often you will need more than one treatment.
Remember that if you suspect you have DCS, never go back in to the water. As you can see, one treatment in a decompression chamber takes hours. You will never reach the same effect by going back into the water. You will only end up making things worse. So always make sure: when in doubt, alert the people around you and seek professional medical help.