What do you think???

[epdagger]

Let me start out saying that I'm no new kid on the block when it comes to scuba and yes I know the stated rules about diving and flying.

My question lays out like this; diving at 70' or less at an altitude of 1,800ft. At a Minimum of 8hrs later you hoop in a non-pressurized plane for a few hours of flight training at an altitude of 4,000ft or less.

Would this be a go or no-go for "YOU" and why?

"MY" logic is:
According to PADI rec. dive tables when at a worst case no deco gas level you will completely off gas in 6 hours.
The altitude will only increase by 1,500 to 2,500 feet which could be achieved by diving on the beach in Panama City and then driving to mid state Georgia or Alabama.

 

[Thalassamania]

Current information says that it is OK to to go to 2,000 (some say 2,700) feet after a no-D dive. 1,800 to 2,500 is less of a ratio change than 0 to 2,000. I'd expect no problem.

 

[Quero]

I would say "fly," but would also add caveats to your thinking.

First, the offgassing-in-six-hours thought can be a little confusing. That six hours is only the time it takes to get you back to pressure group A in the PADI table. It does not mean your tissues are completely clear of excess N2. Ascending to altitude changes the pressure gradient between the dissolved gas in the tissues and the ambient pressure, and taking this into account is the basis for waiting longer periods before flying after diving. Think of it in this oversimplified way--if you shake up a bottle of champagne and then pop the cork, it spews forth, but if you shake it up and then let it sit a while, the frothing is much reduced, even though the bubbles are still in the wine when it is poured.

Second, ascent to altitude is different when done over a period of hours (as when driving from the Florida panhandle to the middle of Georgia) from ascent to altitude that is achieved suddenly in an aircraft. To continue the beverage analogy, if you were able to open that champagne bottle slowly rather than popping the cork, you could reduce the frothing, but when you shake and pop, the expanding gas turns the whole thing into a spectacle of a wine geyser.

 

[Levigarrett]

I would be willing to fly given the profile you've posted here. I've in fact done a far more aggressive dive/fly scenario without incident. Obviously, DCS susceptibility variations are LARGE between individuals so I'm not so sure the experience of others is terribly relevant once you venture beyond published guidelines. You're going to "test pilot" your own physiology in this case...

That being said. I'd make sure I had some kind of hyperbaric insurance policy (DAN) and that I had a contingency plan in the event I thought a DCS hit was imminent.

I'd plan the dive, the flight and the worst case scenario so that all were available to me should it not work out. I know that sounds a bit dramatic but I think it's worth thinking about.

The final variable for you to consider is the flight itself. In this area, I have some expertise. I'm not sure what your experience level is (no offense intended) and if you're going to be operating the aircraft yourself. In my case, I was the PIC and was directing the flight to assure that I was going to be able to guarantee a profile within my tolerance limits. You can "plan" to operate the aircraft at any altitude, however there are several things to consider. Are you going to be able to maintain VFR if that's necessary? Are you going to be getting radar services and if so, how will you comply with a climb requirement is one is issued? In this scenario, you want maximum flexibility and often, wx and ATC fail to cooperate. Plan accordingly.

I can't give you a great deal of diving advice because that's simply not my area of expertise but if you're going to fly the aircraft yourself and have some questions, feel free to shoot me a PM. I'm an ATP with a current CFI,CFII, MEI and I'd be happy to lend a hand should you decide some additional advice is warranted. Take care.

 

[Sat Diver]

breathe pure O2 on the surface after your dive. It will accelerate your N2 diffusion and off gassing.

 

[Levigarrett]

breathe pure O2 on the surface after your dive. It will accelerate your N2 diffusion and off gassing.

He may not be able to get an O2 fill without the proper certs/gear...

 

[Searcaigh]

I have dived with people in Jeddah Saudi Arabia who then drove to Taif after the dive to above 4,000 ft, and as far as I know nobody had DCS.

Everyone is different, but in general it should be okay. You could dive Nitrox of course and that would lessen any risk.

 

[TSandM]

I'd pay close attention to the ascent profile on the dive or dives, and shape it like the decompression curve (faster ascent to midpoint, steadily slowing ascent thereafter). I wouldn't push deco limits. And I'd fly.

 

[drbill]

I guess I'm just more conservative than most when it comes to flying after diving. I always wait a minimum of 24 hours regardless of my dive profiles, often longer than that if I'm flying commercial (our helicopters here on the island fly at low elevation). But then it is sometimes difficult to get me up in an airplane even if I haven't been diving... unless I'm heading TOWARDS a great dive destination (not LEAVING one).

We had a local instructor do a series of standard OW training dives with her students, then drive over to her BF's, reaching a maximum elevation of 1,602' at our airport (she was driving not flying) and get bent to the point she stopped diving altogether.

 

[JohnE]

I wouldn't. Bottom time is important, among other things. Say you are pushing it on time at 70'. You've increased saturation in the tissue compartments that are slower to offgas. Perhaps one day it is slower than usual (worked during SI, stressful week, gained weight, dehydrated, stressful dive, etc...)

Now if you come out of that it is going to take longer for the nitrogen to get out safely. Now pop up to 4000 ft and you've rapidly taken pressure off remaining nitrogen. The rate of ascent is different from driving.

This seems like it is pushing it. I wonder how much damage we do when pushing it that we don't realize, stuff that is small and cumulative.