Is Flying After Diving Safe?

You’ve been enjoying your vacation and diving in some beautiful areas – but as the end of your vacation approaches you scramble to fit in a last couple of dives before flying home. Is it safe to dive the day of a flight? How long of a gap do you need to leave, before taking to the skies after a dive?

Tests were done as far back as 1960 that showed rates of decompression sickness were high in those who had been diving between 4 and 12hrs before taking a flight at an altitude of 8 – 10,000ft.

In the very first test, performed by the Navy, two airline pilots had been diving at a depth of <30 ft, then piloted a plane 4hrs later at an altitude of 8-10,000ft. Both of the pilots became incapacitated – the flight engineer, who had also been diving 12hrs prior, while not affected as severely, were able to land the plane.
This test was conducted to discover the efficacy of decompression after diving and before exposure to altitude. Unfortunately the test never caught on.

Divers Alert Network have also recorded instances where divers have suffered decompression sickness when flying soon after a dive and the speed and severity of the symptoms was in direct correlation to the depth and duration of the dive and the time lapse between diving and flying. Some were affected with a 7 – 12 hr interval and others anything up to 3 days.

In theory it is suggested that a 12hr lapse of time between a dive and a flight, providing it is a single dive, should be safe. However no studies have been done on subjects who dive 2 or 3 times a day for a number of days while on a trip and then fly. It is known that repeated dives in a few days window can cause a build up of nitrogen in the blood and this can lead to problems at altitude. It is also known that the more extreme dives to deeper depths, can also prove problematic, if the subject is then subjected to altitude - however the figures for these kinds of scenarios have not been examined.

It is recommended that an interval before flying should range between 2 and 12 hours for no decompression diving. It is a reasonable recommendation that divers, who have had less than a total of two hours no decompression dive time during the 24 hours before flying, should wait 12 hours before flying. Divers who do multi-day diving should wait 18 to 24 hours before flying, but preferably longer.

Anyone who has been diving, regardless of whether they have been through decompression, may still have small bubbles, which while not enough to cause a problem on the surface, may expand at altitude, causing decompression sickness. Keeping dives conservative will reduce the risk of bubbles.

To improve your risks even further it is recommended that any diving be avoided in the last 48hrs before flying.