"no fly" time

[limeyx]

On the flip side, the Darwin Awards are given to people where the dangerous practice did not turn out so well for them.

Well, since I dont intend to stop doing it, I guess I will let you know how it's going for me.

 

[stiebs]

The last issue of the DAN Asia-Pac magazine had a 3-page research article on flying after diving. I don't have the article with me, but I'll list some of the more interesting points that they made (the ones I can remember, anyway)

The first recorded incident of DCI after flying was when the pilot and co-pilot of a commercial airliner flew within 2 hours of diving to appriximately 10msw. This was in 1961. Luckily the flight engineer managed to land the plan.

DAN is currently in the process of a three phase human research project, the first of two which have already been completed.

Phase one was a sample of around 500 no-deco dry dives at rest, followed by flights. They varied depths (18msw, 30msw) and dive times (40m, 55m) and gradually decreased S.I before simulating a commercial jet flight until the incidents of DCI symptoms greatly increased.

The results were that after an 18msw dive for 40 minutes, the incidents of DCI symptoms after a S.I of only five minutes before flight were around 1%. Yes, 1 in 100. After a 55 min dive at 18msw, the incident of DCI symptoms reached 1% at 2 hrs.

Phase 2 included also included repetitive dives and a decompression dive profile. I can't remember most of the details, but the decompression dive was to 30msw for 120 minutes, and included a 25 minute stop at 3msw. Incidents of DCI symptoms reached 1% after reducing the pre-flight SI down to nothing.

 

[limeyx]

Of course there are other things to consider here, hydration is a BIG deal. Refraining from alcohol and other diuretics is important, drinking water or fruit juice before and during the flight is important, possibly wearing a surgical mask during flight and even hedging your bet with a tank of of oxygen before departure might be prudent moves.


So the only question that remains is, "how do I get back onto U.S. Navy tables when I've been diving a computer?" That can be problematic. When I know I'm going to face this sort of situation I dive a U.S. Navy model computer (an old Edge, Skinny Dipper, or Phoenix). At the end of my last dive I take the scrolling no-D limits and compare them, depth/time pair by depth/time pair to the U.S. Navy No-Decompression Limits and Repetitive Group Designation Table for No-Decompression Air Dives. I take the highest repetitive group designator that this results in and use that to determine how long a must wait until I am in group C.
I DO NOT RECOMMEND THEM TO YOU AS ANYTHING MORE THAN A STARTING PLACE FOR YOU TO BEGIN TO ASK QUESTIONS.

Ulp, so stopping at the airport bar for a beer before the flight would be an uber-bad idea then ?

I honestly wouldn't know a Navy table/group at this point if it bit me on the head.
I am however very interested in this topic in general.

Obviously if I can leave 24 hours, then that's cool but for a weekend I am not willing to dive just the one day, so I will continue doing it the way I have been. For cave trips, it's much easier as we just wrap up diving say at 3-5pm, and then fly out the next afternoon, which does give almost 24 hours.

 

[limeyx]

He's diving in Seattle and lives in Los Angeles, I didn't think he would be on an island hopper.

It's true, no Island hoppers -- I'm willing to take the risk at 8000 feet of pressure, but not so happy with 20K+

I am definitely interested in this new study, but my guess is that the profiles will be pretty dis-similar to the ones I dive, so I dont have that much hope that I will be able to make much use of it.

 

[stiebs]

Ah, I meant to add the summary of phase three to my post above..

Phases one and two were, as I mentioned at rest and dry. Phase three is wet and exercising. The article says this phase is currently under way, but will take much longer, as its easy to sit a dozen people in a dry chamber. But doing a wet and exercising dive simulation can only accommodate a maximum of two divers at a time.

 

[stiebs]

It's true, no Island hoppers -- I'm willing to take the risk at 8000 feet of pressure, but not so happy with 20K+

As has been mentioned a number of times on this thread, even a commercial international flight which will get to altitudes of 30k feet, the cabin pressure always remains at around 8k feet. The only way your body will experience that sort of pressure (or lack thereof) is if you catch a flight to the Andes, Alps, Himalayas or Rockys.

But 8000 feet is still enough to give you a DCI hit if its too soon after diving.

The last liveaboard I went on ended with a 2hr flight from Lizard Is to Cairns (Great Barrier Reef). The flight was chartered by the dive op, and at special request the cabin was pressurised to 1atm for the whole flight. The flight was after an SI of around 15 hrs, with 11 dives over the past 3 days.

 

[limeyx]

But 8000 feet is still enough to give you a DCI hit if its too soon after diving.

The last liveaboard I went on ended with a 2hr flight from Lizard Is to Cairns (Great Barrier Reef). The flight was chartered by the dive op, and at special request the cabin was pressurised to 1atm for the whole flight. The flight was after an SI of around 15 hrs, with 11 dives over the past 3 days.

Yes, like I said -- I am willing to take 8K which is what I will experience on pressurized jets.

I wonder if this invalidates my DAN insurance if I do take a hit ? good thing I didn't post my full name I guess !

 

[Thalassamania]

The flight was chartered by the dive op, and at special request the cabin was pressurised to 1atm for the whole flight. The flight was after an SI of around 15 hrs, with 11 dives over the past 3 days.

What kind of plane? At last check (and I don't really keep up on these things) only a Lear Jet and a C-130 Hercules could pressurize to sea level.

 

[Gene_Hobbs]

Ah, I meant to add the summary of phase three to my post above..

Guess post #12 was too 'technical'.

and there is still a need for subjects... anyone...

 

[rjack321]

I have been on 19-seat planes from Denver to Wyoming which was only pressurized to 12.5k - I know I had an altimeter with me. That said I dive and fly on larger jets with cabin pressures in the 8K range all the time. And alot of diving too, like 26 dives, 30+hrs of BT, in 11 days. And deco dives. If you use proper gases and do good clean ascents its fine. If you dive like most of the world does with air and only do shallow "safety stops" after excess rates of ascent, you'll be in a world of hurt.