Scuba Diving 101: Flying After Diving
One of the things you’ll learn during your open water certification is that you can’t just get on a plane after you get out of the water from your dive. You learned that you’ll have to wait. But how long should you wait? 12 hours? 18? Or even 24? And why? What’s the big deal about flying after diving?
The big deal is DCS (Decompression Sickness). When you’re diving, your body needs time to off-gas the excess nitrogen that build up during your dive while you’re ascending. Your ascent should be slow and it’s recommended to do a safety stop before exiting the water. Doing this helps avoid bubbles forming in your bloodstream—possibly leading to DCS.
It’s similar on an airplane because of the decreasing atmospheric pressure as you ascend. Airplane cabins may be pressurized, but they only go up to around 11 or 12 psi at cruise altitude. This is still a significant decrease from sea-level pressure, which is approximately 14.5 psi. During the ascent, excess nitrogen can form bubbles if there’s still too much of it left in your body.
How long should I really wait to fly?
Unfortunately, there’s not just one straightforward answer to this question. It all depends on the risk that you’re willing to take, how many dives you’ve done, and the maximum altitude that you’ll be flying at. There are several organizations that have surface interval after diving recommendations based on their data on post-dive flights:
DAN (Divers Alert Network)
12+ hours for a single ‘no decompression’ dive
18+ hours for multiple dives in a day as well as multiple days of diving.
24+ hours for decompression dives.
U.S. Air Force
24 hours
U.S. Navy
2 hours
PADI (Professional Association of Diving Instructors)
12+ hours for a single ‘no decompression’ dive
18+ hours for multiple dives
24 hours is the ideal recommended interval
Frustratingly, it’s clear that these recommendations are conflicting one another. So which should you follow? The DAN guidelines are great where the number and the type of dives has been taken into consideration.
The only way to completely avoid the risk of DCS would be not to dive at all, but as a diver wanting to enjoy our beautiful underwater world, that’s not an option. So enjoy your dives, but use your own judgement when it comes to what rules to follow regarding diving and flying. Most researchers believe that a 24-hour surface interval is sufficient to prevent flying induced DCS.
Dive Computers
Some dive computers can be useful when it comes to flying after diving, but most are not. There are two ways that dive computers will calculate the ‘no fly time’ after diving:
Countdowns of 12 or 24 hours. These are simple timers that do no calculations, but remind you of the 12 hour or 24 hour rules.
Desaturation countdown. These computers calculate the time to total desaturation and use that as the time needed before you’re able to fly. It’s a very conservative way, but more realistic than the 12 to 24 hour timekeepers.
Enjoy your dives and be smart when it comes to boarding a plane after. Know the symptoms of DCS so you can monitor yourself and your dive buddies—and be conservative. It’s always better to be safe than sorry. Happy diving!