Flying After Diving: How Long to Wait Before You Fly

How long to wait before flying after diving

The most widely used numbers come from the 2002 Flying After Diving Workshop, which DAN held with the Undersea and Hyperbaric Medical Society (UHMS). They are minimums for divers without symptoms, not guarantees, and a longer wait lowers the risk further.

The workshop wrote them for air dives followed by flights at cabin altitudes of 610-2,438 m (2,000-8,000 ft). DAN considers a flight below 610 m mild enough to need no special wait, which covers some short, low inter-island hops. Going above 2,438 m after diving is not recommended until the excess nitrogen is gone.

Tables and computers carry their own numbers, and they do not always match the consensus. Our DECO 2000 table, for example, gives a flight wait for every end-of-dive group letter. The comparison further down shows how far the sources spread.

Where the 12 and 18 hour numbers come from

Mostly from chamber trials at Duke University, funded by DAN and run between 1992 and 1999. Dry, resting volunteers made one to three dives in a day to 12, 18 or 30 m (40, 60 or 100 ft), close to the no-decompression limits, then spent four hours at a simulated 2,438 m (8,000 ft). There were 40 cases of decompression sickness (DCS) in 802 exposures of 495 people.

The risk fell as the surface interval grew, and repetitive dives needed longer waits than single dives. After single no-stop dives to 18 m or deeper, nobody developed DCS with intervals of 11 hours or more. After repetitive dives, cases still occurred with intervals under 17 hours. The longest interval tested was 17 hours, with no DCS in 52 trials.

The workshop named the weak point itself: real divers are wet, working and diving for days, so real-world intervals may need to be longer. A 2015 DAN Europe study scanned 56 divers during the flight home after a week of tropical diving and a 24-hour wait. Nobody had detectable bubbles before takeoff, but 8 did in the air, all from the group that bubbled after almost every dive. None had symptoms. DAN's review of the study concluded that 24 hours is probably safe and that the 18-hour interval may deserve another look.

How other guidance compares

The sources do not all agree. Fixed-hour advice runs between DAN's 12-hour minimum and a flat 24 hours, while profile-based methods such as the US Navy tables and DECO 2000 can give shorter waits after light dives and longer ones after heavy days.

A worked example with our DECO 2000 planner: one dive to 18 m (60 ft) for 35 minutes ends in group E, and the table's flight column gives 16 hours. The 2002 consensus minimum for that same single no-decompression dive is 12 hours. Add a second dive that day and the consensus moves you to at least 18 hours, and a long day can end in group G, which the table pairs with 24 hours.

The US Navy method is more flexible, but DAN points out that it is a mathematical treatment of largely the same trial data, and it needs a repetitive group, which dive computers do not give you. Computers are a separate case: DAN notes that many display a no-fly time but the methods vary between models. Shearwater chose not to show one, because the guidelines depend on things a computer cannot know, such as whether you have symptoms.

Why cabin altitude matters

An airliner cabin is not kept at sea-level pressure. US certification rules for transport aircraft require pressurized cabins to provide a cabin pressure altitude of no more than 2,438 m (8,000 ft) under normal operating conditions, and DAN says the effective cabin altitude usually sits around 1,800-2,400 m (6,000-8,000 ft). At 2,438 m the air pressure is roughly three quarters of the sea-level value.

Real flights vary. A 2013 study carried an altimeter on 207 US domestic flights and measured an average peak cabin altitude of 1,933 m (6,341 ft). About 10% of flights went above 2,438 m, while 70% of flights shorter than 500 miles (about 800 km) stayed below 1,524 m (5,000 ft).

For a diver this is one more step of decompression. In DAN's example, surfacing from 20 m (66 ft) is a threefold drop in pressure, and boarding a plane with a 2,438 m cabin turns it into roughly a fourfold drop. In a DAN Alert Diver article, Richard Vann adds that by Boyle's law any bubbles present expand by about a third at that cabin altitude, and nitrogen from the surrounding tissue then diffuses into them. A rare cabin depressurization would add far more.

Mountain roads and altitude after diving

A mountain road is the same problem at a slower pace. DAN states that any ascent to a higher altitude after diving, including by road, increases decompression stress, and advises keeping the final dives more conservative, delaying the trip to altitude, or both. The 2024 review notes that DCS can appear later than usual when a diver drives up high roads or flies.

We found no consensus guideline written only for driving after recreational diving. The flying guidelines cover 610-2,438 m (2,000-8,000 ft), and a road over a 1,500 m pass takes you into that band. In a DAN answer on pool sessions, driving to an altitude is weighed the same way as a flight with a similar cabin altitude. The PADI blog suggests ideally 24 hours before driving to altitude, or a lower route. The US Navy tables handle it directly, since their wait depends on the altitude you will reach.

Altitude also changes the dive itself. Lower surface pressure shortens no-decompression limits, so mountain-lake dives need altitude-corrected tables or a computer set for altitude. Tables are built for a stated altitude range: DECO 2000, for example, covers 0-700 m.

What to do if symptoms appear before or during a flight

Before the flight, do not board. The 2002 workshop found that more divers fly with symptoms than develop them in the air, and concluded that flying with symptoms may be the bigger health problem. DAN's advice is to seek medical advice instead of flying, and after skin bends not to fly until a doctor familiar with diving medicine clears you.

DAN has published one such case. A diver with itchy, mottled skin after three days of diving felt better after 30-45 minutes of oxygen at a clinic and later took her scheduled 30-minute flight home. The morning after the flight she was in considerable pain with a swollen abdomen, and she was treated in a chamber four days after her last dive.

During the flight, tell the cabin crew about the diving and the symptoms. Aviation medicine guidance summarized in StatPearls calls for 100% oxygen by face mask, lying flat if unconscious, descent with the intention to land, and assessment after landing by a clinician who knows aviation or hyperbaric medicine, even if the symptoms have gone. On an airliner, what the aircraft does is the crew's decision.

After landing, or if symptoms start later, call local emergency services and DAN (+1-919-684-9111, or DAN Europe on +39 0642115685). Late onset does happen: DAN says delayed symptoms are rare but can happen, especially when air travel follows diving, and the 2024 review reports DCS symptoms in divers who flew more than 24 hours after diving. This page is general information, not medical advice.

Planning the last dive day around a flight

Count back from takeoff, not from the time you leave for the airport. For a 10:00 flight after a week of diving, the 18-hour minimum means surfacing from your last dive by 16:00 the day before. A 24-hour margin moves that to 10:00 the day before, which usually rules out that day's afternoon dives.

• Use the longest of the consensus minimum, your table's flight wait and your computer's no-fly time.
• Keep the final day's dives shallow and short, or skip them. In the 2015 in-flight study, the two divers with the highest bubble scores skipped the last dive, flew about 36 hours after diving and had no bubbles on the flight home.
• Count a drive over high ground on the way to the airport as part of the plan, since DAN treats any post-dive ascent to altitude as added decompression stress.