I normally don't hang out here in the deco section... I'm simply not knowlegable on the subject, and don't want to open my mouth and say something stupid.
...But your direct question is something that I can speak on.
I just did a "Flying After Diving" study with Duke University, which is funded by DAN, and in this case, the United States Navy.
Their research is ongoing, too. I suggest you give the Hyperbaric Facility at Duke a phone call. Ask to speak to Eric. Tell him SeaJay sent you, and you'd like to ask him some questions. He's extremely knowlegable.
The bottom line is that they're doing research on exactly what you're talking about... Because previous research, from which we gleaned the rule of "no flying 24 hours after diving," has been found to be at best inconclusive, and at worst incorrect. I saw the data myself.
When they started the recent re-testing, they chose a dive profile that was very conservative, and followed it up with a very low "flight." Since the facility is able to detect DCS far before it becomes obvious to the patient, they were not looking to bend anyone... They were looking for the symptoms. It's safe to assume that the more aggressive the dive profile became, and the more aggressive the flight afterward became, the more symptoms they'd get, right? Heck, simply changing the surface interval should bring some symptoms out.
Well, the research (which is impressively thorough) did not find the symptoms they expected.
...So they've kept testing and testing. There's been several hundred people who have participated at this point... With very little to show in terms of symptoms. So... Each time, they've gotten more aggressive with the profile.
My "dive" profile (a month and a half ago) was 60 feet for 40 minutes, 1 hour SI, followed by a 4 hour flight at 8,000 feet. Why 4 hours at 8,000 feet? Well... Most commercial airliners pressurize their cabins to that pressure (or roundabouts), and 4 hours pretty much gets anyone home from most dive locations.
Nobody in our group experienced any symptoms of DCS... And only one actually had any bubble formation that was detectable. Far from DCS, this was sort of a "precursor" to DCS, and entertained us all considerably, including the patient. These were more like pre-microbubbles.
The next profile will be 60 for 40, zero SI, and 8,000 for four hours. The scientists have theorized that there won't be a radical difference in results. I tend to believe them... There's not much of a better bunch of "experts" in the world.
The whole project was amazingly enlightening. I learned much about how my body reacts to pressure from being able to do it dry, sitting in a chair, observing the results. For example, I was surprised to find that our voices changed considerably, even with no change in atmospheric chemistry. The denser air did amazing things. It doesn't require helium to get you to talk like a duck, you know... Although it no doubt makes it even worse.
...What was also fascinating was the unbelievable temperature change in a matter of about two minutes... Going to depth, we saw a temperature change of about 15*. That is, the room went from 75 to 90 in two minutes, without anything blowing... No heaters, no fans, no nothing. It was very weird.
...What was even weirder was feeling the temperature drop the same amount on decompression, again without anything blowing in cold air. Much to the delight of everyone involved, "fog" appeared before our very eyes, thick enough to obscure the person sitting next to each of us. It was truly amazing.
I also had the delight of watching every single person get completely stoned out of their mind when we dove. We all narced hard. Pressure built, and we "descended" for two minutes. When we got to the "bottom" and we all let go of our noses (for ear clearing) we were all very, very quiet. I nudged the person next to me, who had grown fuzzy hair everywhere and said, "Duuuude... Do you feel that?" He 'bout died laughing... While trying to hold it in and giggling/spitting all over himself. He fell off his chair - forward - and the place turned into a complete riot. I mean, we were all super-stupid. It was one of the funniest moments of my life, but for the life of me, I can't remember what the heck we all thought was so funny. Then... In an instant, we were all completely sober. The whole "narc" lasted like 30 seconds, and was gone instantly.
The scientists, some of whom were "riding" with us, seemed unsurprised. "It's normal," they said (while laughing/spitting on themselves).
Yes, it was truly enlightening... And I learned a lot about diving that day. And I highly recommend it to any diver... Finally, you get to find out what YOUR body does under pressure, how to avoid DCS, what
really to look for, and what DCS really means.
Frankly, I have much less fear of it now... And am simultaously a safer diver. Education is a beautiful thing.
My $120 check I received for participating (and free DAN Preferred insurace for a year, not to mention free hotel... Dinner... Good friends...) was great. I spent it on diving.
PM me if you'd like to participate; I'll get you the info.
