Of all the Frequently Asked Questions in Scuba Diving, queries regarding the proper time to fly after diving is one of the most common asked. The dilemma usually crops up, cos as divers we are always keen to squeeze in those few extra dives just before we have to make the most of our diving trips, after-all you just heard the other divers spot a manta ray at a particular dive site, what if it’s still around this afternoon? or you really wanted to have one last look at the amazing Electric Flame Scallop you’ve never even heard of before…whatever the reasons you’re wondering whether it’s reasonable to dive on the day of departure or the evening/night before an early flight.
The U.S. Navy tables recommend that you wait at least two hours before you board a plane after scuba diving; the U.S. Air Force says you should wait 24 hours; DAN recommends a 12-hour minimum surface interval before flying; PADI Flying After Diving guidelines say that you should not go to an altitude (fly) within 12 hours of completing a single dive or 18 hours when doing multiple dives (where possible wait 24 hours)….So which guideline should you follow?
Truth of the matter is that ascending to an altitude immediately after diving causes a significant risk for decompression sickness. Flying after diving, increases this risk because of the decreasing atmospheric pressure as we ascend. You might have only a few tiny bubbles, causing no problems at all, in your body when you reach the surface after a dive. If, however, you go flying, the small bubbles can expand (due to the reduction in pressure with altitude) and could cause the onset of DCS symptoms.
So what’s the minimum time you should give before flying after diving?
Unfortunately, there’s no straightforward correct answer to the question. It all boils down to the risk you are willing to take.
The current winner of the debate is a DAN guideline which states:
a. A minimum surface interval of 12 hours is required before ascent in a commercial aircraft (8000 foot (2438 m.) cabin).
b. Wait an extended surface interval beyond twelve hours (18 hours or more is suggested) after daily, multiple dives for several days or dives that required decompression stops.
c. The greater the diving the longer the duration (some sources say 24-48 hrs) recommended before flying.
The above is for sports diving and should not apply to commercial diving or nitrox diving. Because of the complex nature of DCS and because decompression schedules are based on unverifiable assumptions, there can never be a fixed flying after diving rule that can guarantee prevention of bends completely.
Whether you wait 12 hours or 24 hrs there are no guarantees that you won’t get decompression sickness when you fly. However, the longer your pre-flight surface interval time, the more nitrogen you expel from your system which minimizes the risk of decompression sickness. We recommend you use your judgment and consider some factors before making your decision like- The number of previous dives you’ve made on this dive trip, type of dives (decompression, non-decompression, altitude dives, nitrox etc), your general health and your age. The estimated DCS probability for the 12-hour flying-after-diving surface interval is about 1 percent. Of the 300,000 to 400,000 people who fly home 12 to 24 hours after their last dive, the estimated incidence of decompression sickness among these divers is about 0.004 percent, making the 12-24 hour rule the most followed among divers across the world.
Divers Alert Network