pdxgal
Registered
What's the connection between flying, diving, and going up a mountain? Sorry, very basic question. I should know this but I'm the mom of a toddler and my brain is half liquified as a result. Too much Elmo.
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KevinNM
Contributor
Briefly, going up in elevation or traveling on aircraft reduces air pressure. That encourages nitrogen in solution in your body from diving to come out of solution. Which can lead to DCS if you have not waited enough time after diving before flying or driving over a mountain.
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pdxgal
Registered
Gotcha. So can I dive the day I fly in?
KevinNM
Contributor
Yes, the flying out part is where you need to stop diving 18-24 hours before the flight. Also you need time after diving before driving over a mountain, as happens in Hawaii.
KevinNM
Just how much problem is it to drive up a mountain as the pressure change is very slow and not like getting on a plane and changing 14.ooo feet in a feet minutes. If themountain drive change was as much as 5# pressure that is equivilant to 10 ft of water. Wouldn't a surface from 10 ft over an hour or 2 be well with in a safety zone???
Just how much problem is it to drive up a mountain as the pressure change is very slow and not like getting on a plane and changing 14.ooo feet in a feet minutes. If themountain drive change was as much as 5# pressure that is equivilant to 10 ft of water. Wouldn't a surface from 10 ft over an hour or 2 be well with in a safety zone???
KevinNM
Contributor
Last time this was discussed it was determined the no-fly stuff was based on commercial aircraft, which is typically designed to have a maximum pressurization altitude of 8,000 feet. They do this slower than the actual change in altitude. If your plane loses cabin pressure at 29,000 feet, well this is not covered by the DAN guidelines.
I'm pretty sure saddle road in Hawaii, between Kona and Hilo, is at about the same elevation that a commercial airplane to pressurized to, about 7 to 8 thousand feet. So if you hopped out the the water at the Kona marina after a couple days of diving and drove directly towards Hilo this might be bad. If for some reason you decided to drive to the the observatory at 13.000 feet instead this would probably increase your chance of a bad day somewhat. How big a chance of something bad happening I don't know, it probably depends on a bunch of things about you and your dive profile.
I normally dive dive at a site at about 4600 feet and an hour towards Albuquerque there is a ridge that rises to 7000 feet. I don't personally know of anyone who has had a problem here, but I've heard that people have occasionally (rarely) managed to find themselves in some trouble if they work hard to immediately leave and drive fast to there. The normal rule of thumb was to wait around in town for about two hours, having lunch and putting gear away, before driving back to Albuquerque.
I'm pretty sure saddle road in Hawaii, between Kona and Hilo, is at about the same elevation that a commercial airplane to pressurized to, about 7 to 8 thousand feet. So if you hopped out the the water at the Kona marina after a couple days of diving and drove directly towards Hilo this might be bad. If for some reason you decided to drive to the the observatory at 13.000 feet instead this would probably increase your chance of a bad day somewhat. How big a chance of something bad happening I don't know, it probably depends on a bunch of things about you and your dive profile.
I normally dive dive at a site at about 4600 feet and an hour towards Albuquerque there is a ridge that rises to 7000 feet. I don't personally know of anyone who has had a problem here, but I've heard that people have occasionally (rarely) managed to find themselves in some trouble if they work hard to immediately leave and drive fast to there. The normal rule of thumb was to wait around in town for about two hours, having lunch and putting gear away, before driving back to Albuquerque.
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I have no Altitude cert. and have never done it, but I know there are special tables and computer settings for this. It make sense to me that it depends on how high and fast you drive up and how close you are then (after a dive) to the no-stop limits for whatever altitude. I would think going up the equivalent of 10 feet of water in whatever amount of time could be a problem if you then altitude dive very close to the no stop limit.
freewillie
Contributor
The connection is pressure and in particular ambient pressure. Under water there is increased atmospheric pressure exerted by the water. This forces extra gas to be dissolved into the blood. As the diver rises and the pressure becomes less then there is the possibility depending on how much gas was dissolved that the excess can then form bubbles in the blood. This results in the decompression illness and depending on where the bubbles form will determine what symptoms the diver experiences.
From sea level if you continue to go up in elevation then the atmospheric pressure becomes even less and this can also precipitate decompression illness or exacerbate the condition. Generally speaking you should limit the rise in elevation to about 2000 feet at the most. Since most commercial airlines will exceed the recommended limits even if the cabin is pressurized there is a time limit between your last dive and when you can fly. But there is no restriction going from altitude like flying to diving. So you can safely fly into your resort and if it is early enough to catch a dive then you can consider going diving in the afternoon on the same day you arrive.
Waimea on the Big Island of Hawaii is just over 2,000 feet. Many of the workers on the dive boats live there and can safely dive then drive home without waiting. But the saddle road to Hilo and Volcanoes National Park goes over the volcano at 7,000 feet and is not advisable route to drive after diving.
From sea level if you continue to go up in elevation then the atmospheric pressure becomes even less and this can also precipitate decompression illness or exacerbate the condition. Generally speaking you should limit the rise in elevation to about 2000 feet at the most. Since most commercial airlines will exceed the recommended limits even if the cabin is pressurized there is a time limit between your last dive and when you can fly. But there is no restriction going from altitude like flying to diving. So you can safely fly into your resort and if it is early enough to catch a dive then you can consider going diving in the afternoon on the same day you arrive.
Waimea on the Big Island of Hawaii is just over 2,000 feet. Many of the workers on the dive boats live there and can safely dive then drive home without waiting. But the saddle road to Hilo and Volcanoes National Park goes over the volcano at 7,000 feet and is not advisable route to drive after diving.
The biggest concern in diving AFTER flying is that you are often dehydrated from the flight, and the dehydration is a risk factor for DCS. So stay hydrated on the plane.
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