Flying After Diving: How Long to Wait (12, 18 or 24 Hours)

How long to wait before flying after diving

The numbers most dive centres use 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, counted from the moment you surface after your last dive until the plane takes off. They lower the risk but do not remove it.

The workshop wrote them for air dives followed by flights at cabin altitudes of 610-2,438 m (2,000-8,000 ft), which covers airliners. To check a real flight, enter your surfacing and takeoff times in our no-fly time calculator. It applies the same 12, 18 and 24 hour minimums and shows the 24 hour line next to them. For the opposite question, diving soon after you land, see diving after flying.

How the waiting time differs by source

The sources agree that more diving needs a longer wait, but they put the line in different places. Fixed rules sit between 12 and 24 hours. Profile-based methods such as the US Navy tables give a short wait after a light dive and a long one after a heavy day, and dive computers each count in their own way.

The US Navy table needs your repetitive group (the highest one from the last 24 hours) and the altitude you will reach, and for an airliner the manual says to use 8,000 ft. We ran three dives through the site's copy of the Rev 7 tables. One dive to 18 m (60 fsw) for 35 minutes ends in group G, which needs 9 h 13 min before a flight. Add a second dive to 12 m (40 fsw) for 40 minutes after a one-hour surface interval and the group becomes J: 14 h 13 min. A decompression dive to 30 m (100 fsw) for 40 minutes ends in group M: 18 hours. Groups A to C may fly straight away, and group Z needs 21 h 01 min.

Other tables land elsewhere. In our DECO 2000 planner the same 35 minute dive to 18 m ends in group E, and the table's flight column gives 16 hours, so one dive gets 9, 12, 16 or 24 hours depending on whom you ask. DAN notes that the Navy method is a mathematical treatment of largely the same chamber trials behind the 12 and 18 hour rule.

Computers differ too. Garmin's Descent watches step through 12, 18 and 24 hours, or show a flat 24 hours if you pick that setting. Suunto shows 12 hours or its calculated desaturation time, whichever is longer, with no separate step for repetitive diving. Shearwater shows no time to fly at all, because the guidelines depend on things a computer cannot know, such as whether you have symptoms. When the numbers differ, use the longest one.

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. Later Duke trials showed how much the profile matters: the low-risk wait after a 40 minute dive to 18 m was nearly 12 hours shorter than after a 55 minute dive to the same depth.

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 than the ones that worked in a dry chamber.

Can I fly 24 hours after diving?

Yes, after recreational no-decompression diving. 24 hours meets the DAN, PADI, BSAC and DMAC numbers and every US Navy group, and it is the wait PADI and BSAC suggest. After decompression dives, 24 hours is the lowest number DAN shows, so treat it as the minimum. Your computer can still ask for more: Suunto counts its desaturation time when that is longer, and Garmin and Suunto both set 48 hours after a missed decompression stop.

Field data support the 24 hour line. A DAN case-control study of 627 recreational dive profiles (Freiberger 2002) found that divers who flew 24-28 hours after diving had about the same odds of DCS as those who waited more than 28 hours (odds ratio 1.02).

It is still not zero risk. 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 of them divers who had produced bubbles during the week. 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, and a 2024 review reports DCS symptoms in divers who flew more than 24 hours after diving.

What if you have to fly sooner?

The risk climbs as the wait gets shorter. In the same DAN study, compared with flying more than 28 hours after diving, the odds of DCS were 1.84 times higher with a 20-24 hour wait and 8.5 times higher below 20 hours. The authors wrote that the relative risk increases geometrically as the interval shrinks. Depth on the last day mattered as well: last-day dives deeper than 26 m carried 5.5 times the odds of dives shallower than 14.7 m.

If the flight cannot move, the choices are on the diving side. Skip the last dive or the last day, or keep the final dives shallow and short. The 2002 workshop noted that breathing oxygen before a flight might reduce the risk, based on military trials, but no guideline turns that into a shorter wait.

Can you dive and fly within 24 hours? Yes, as long as the minimum fits. Surface from a single morning dive at 10:30 and the 12 hour minimum allows a flight from 22:30 the same day. After two dives that end at 15:00, the 18 hour minimum moves the earliest takeoff to 09:00 the next morning.

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), which is still inside the range the guidelines cover.

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. Any bubbles present expand by about a third at that cabin altitude, and nitrogen from the surrounding tissue then diffuses into them.

The guidelines were not tested above 2,438 m. DAN Southern Africa suggests doubling the usual times for cabin altitudes of 2,438-3,048 m (8,000-10,000 ft), where low oxygen adds to the stress, and at least doubling them if the flight home lands at an airport above 2,438 m.

Helicopter flights and mountain roads after diving

A helicopter or small plane with an unpressurized cabin puts you at the altitude it flies, and DAN treats that the same way as driving to the same height. The airline guidelines say little about low flights. Writing for DAN, Neal Pollock says exposures below 610 m (2,000 ft) are ignored by the guidelines, while DAN Southern Africa says a slightly shorter wait is possible in theory below that height but suggests following the normal guidelines anyway. The US Navy counts any ascent above 300 m (1,000 ft): at that height groups A to J need no wait and group Z needs 5 h 56 min.

Commercial diving has the clearest helicopter rule. DMAC, the UK-based committee that writes medical guidance for commercial diving, allows a flight that stays below 600 m (2,000 ft) on a checked flight plan 2 hours after no-stop dives with under 60 minutes under pressure, and 12 hours after other air or nitrox diving. For a scenic flight after a holiday dive, ask the pilot how high the route goes and use the airline wait if it will climb above 610 m.

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. A road over a 1,500 m pass takes you into the same band as an airliner cabin, and the PADI blog suggests ideally 24 hours before driving to altitude, or a lower route. The 2024 review notes that DCS can appear later than usual when a diver drives up high roads or flies. If the dive itself is at altitude, our guide to planning an altitude dive covers going higher afterwards.

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 felt better after oxygen at a clinic, took her 30 minute flight home, woke the next day in considerable pain and needed chamber treatment 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. DMAC separates the cases: pain in a limb alone may allow the flight to continue with pain relief, fluids and oxygen, while any other symptom calls for 100% oxygen, specialist advice and possibly a lower cabin altitude and a diversion. 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). DAN says delayed symptoms are rare but can happen, especially when air travel follows diving. Our guide to decompression sickness symptoms and first aid lists the signs to watch for. 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. The no-fly time calculator does this count for any surfacing and takeoff time.

• Use the longest of the DAN 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, and add time for a long trip home with several take-offs.