flying after diving

Do you know that flying after scuba diving is a no no? This is a vital piece of information for pilots and also for travelers who plan their scuba diving trips by flying to their destinations. However, you can scuba dive when you reach your destination after you fly. Why is that so? Read on…

You increase your risk of decompression sickness if you don't wait long enough to fly after diving! A scuba diver needs to be aware of the health risk of residual nitrogen leading to decompression. Because air under high pressure is compressed, each breath taken at depth contains many more molecules than a breath taken at the surface. The extra nitrogen molecules accumulate in the blood and tissues. As outside pressure decreases during ascent from a dive, the accumulated nitrogen that cannot be exhaled immediately forms bubbles in the blood and tissues (Merck, 2009). If you fly after diving you risk extremely painful gas bubbles forming in your joints and flesh, or tragically in your blood, leading to an embolism and possibly even death! (the scubaguide.com, 2009)

It is the same when you are climbing in an aircraft or ascending to the surface of the water. The difference in air pressure, as a plane climbs to cruising altitude, is more or less equivalent to the last 14-16 feet of ascension in water and the same risks are evident including the bends (decompression sickness) and/or an embolism (the scubaguide.com, 2009). These bubbles may expand and injure tissue, or they may block blood vessels in many organs—either directly or by triggering small blood clots. Nitrogen bubbles also cause inflammation, producing swelling and pain in muscles, joints, and tendons (Merck, 2009).

When do we get bubbles forming?

1. Ascend to the surface after a dive
2. Ascend to altitude after a dive (a continuance of the dive while flying)
3. Ascend to a high altitude from the surface without pressurization.
*Therefore we need to allow the nitrogen to wear off after diving (the same reason we spend a designated time on the surface between dives). (Campbell, 2009)

Decompression sickness

Decompression sickness is a disorder in which nitrogen dissolved in the blood and tissues by high pressure forms bubbles as pressure decreases (Merck, 2009).

Symptoms
Only half of the people with decompression sickness have symptoms within 1 hour of surfacing, but 90% have symptoms by 6 hours. Symptoms commonly begin gradually and take some time to reach their maximum effect. The first symptoms may be fatigue, loss of appetite, headache, and a vague feeling of illness. (Merck, 2009)

Flying after diving guidelines

The Flying After Diving Workshop held in May 2002, in Durham, North Carolina, USA, produced some new flying after diving recommendations. They apply both to Recreational Dive Planner and dive computer guided dives and are important for anyone considering dive travel. Recent experimental trials indicate the risk of decompression sickness (DCS) decreases as the preflight surface interval increases. Based on these studies, the Workshop reached the following consensus recommendations.

For Dives within the No-Decompression Limits
- Single dives - a minimum preflight surface interval of 12 hours is suggested.
- Repetitive dives and/or Multi-day dives - a minimum preflight surface interval of 18 hours is suggested.

For Dives requiring Decompression Stops - A minimum preflight surface interval greater than 18 hours is suggested.

Flying after diving recommendations need not be considered for flights to ambient/cabin pressure less than 600 meters/2000 feet. (Cool Blue Scuba, 2009)

Other alternative guidelines
A good conservative rule is to ensure that you have no residual nitrogen in your body before flying. Following the NAUI dive tables, you should be in letter group A or less (which can take over 9 hours). A safe suggestion is to pass a full 24 hours after your last scuba dive before flying.
Dive computers, which track nitrogen levels, have a "time-to-fly" indicator, which tells a scuba diver how long they need to wait before boarding a plane. Plan your last dive sensibly, so that you aren't bringing nitrogen along for a painful and possibly fatal return trip. (the scubaguide.com, 2009)

More information:

1) FAA Pilot safety brochure: Altitude-induced decompression sickness

http://www.faa.gov/pilots/safety/pilotsafetybrochures/media/DCS.pdf

2) FAA publication: Medical Facts for Pilots
http://www.faa.gov/air_traffic/publications/ATpubs/AIM/Chap8/aim0801.html

References:

Campbell, E.S. (2009). Flying after Diving. Retrieved Oct 1, 2009 from
http://scuba-doc.com/flyngaft.htm

Cool Blue Scuba. (2009). 8 Most Common Scuba Diving Questions. Retrieved Oct 3, 2009 from
http://www.coolbluescuba.com/scubaquestions.html

Merck. (2009). Decompression Sickness. Retrieved Oct 1, 2009 from
http://www.merck.com/mmhe/sec24/ch295/ch295d.html#sec24-ch295-ch295c-247

The scubaguide.com. (2009). Flying after diving. Retrieved Oct 2, 2009 from
http://www.thescubaguide.com/godiving/flying-after-diving.aspx

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