Is it safe for me to fly? I really need to get home.

[inquis]

it would be below 10% in 12 hours, and that it would be safe enough to fly

I agree and would fly with 10% excess nitrogen at sea level, given your description of how that's defined.
EDIT: [just ran the numbers again, and I was actually looking at 5% excess nitrogen. Thinking about it further, I don't have a firm grasp how the excess nitrogen metric stacks up against the Navy guidance. I'd have to see those results to make an informed assessment.]

ETA: you might want to run through the Navy Ascent Table and see where the Excess Nitrogen metric lands after following their guidance on various dives.

 

[tursiops]

The proceedings of the 2002 DAN Flying After Diving workshop are available directly from DAN's publication library; but unfortunately, I cannot attach the entirety due to copyright issues.

https://scubaboard.com/community/resources/flying-after-diving-dan-workshop-report-2002.19/

 

[L13]

Your original statement was not about "excess nitrogen", it was about looking at the GF on a Garmin or Shearwater computer.

The GF's were for initially surfacing from the dives. I wouldn't consider this if the the surfacing GF's were not significantly below 50% (note the <<, not just <). This is because 12 hours might not be enough to flush out the micro-bubbles that developed on initial surfacing with significant GF, even if dissolved nitrogen was low enough at flight time.

The Garmin does not display current GF during the surface interval, it gives you tissue graphs and excess nitrogen for the peak tissue during the surface interval. That is why I changed my nomenclature when discussing values during the surface interval. I was wrong to mention the Shearwater in this context, and I was wrong not to be more explicit in my initial post about exactly what I was referring to.

If you fly with a 10% sea-level GF, it is highly likely that you will develop DCS -- thus the "absolutely do not do this" in my initial posting. For an indication of the kind of risk flying with a 10% sea-level GF would entail on that single Duke dive, that is reached a mere 69 minutes after surfacing.

I agree, that a sealevel GF >= 0% is unsafe no mater the surface interval. Definitely GF=10% would be very dangerous! If it was in tissue 16, that would be over GF=110% at 8K, It wouldn't drop below 50% unless the limiting tissue was 6 (GF~=45%) or lower.

But, the excess nitrogen and tissue graphs of the Garmin do give you a measure of inert gas loading below GF=0 and above surface equilibrium that could be used for a more precise answer than using an arbitrary number of hours regardless of dive history/profiles (if you understand it).

In any regard, I should not have mentioned it because the thread was originally in "Basic Scuba" and using this feature would definitely not be that.

 

[BlueTrin]

IIRC, my Terric did show me off gassing, or something, on the plane.

Even though I had no more than sea level, in me.

I'll have to snap a pic next time.

Did you tell the pilot to ascend by 3m steps?

 

[L13]

EDIT: [just ran the numbers again, and I was actually looking at 5% excess nitrogen.

5% is what I mentioned for my most recent Cozumel trip after a 41h surface interval. That is probably why you were looking at that number.

Thinking about it further, I don't have a firm grasp how the excess nitrogen metric stacks up against the Navy guidance. I'd have to see those results to make an informed assessment.]

ETA: you might want to run through the Navy Ascent Table and see where the Excess Nitrogen metric lands after following their guidance on various dives.

I agree. I need to look at it more.

When I took my first remote trip with the Garmin, I freaked out when I saw a non-zero percentage (I think it was 7%) on the Surface Interval app as I was approaching a flight ~30h after my last dive. At the time I investigated enough to come up with an explanation and some personal metrics for when even 24 hours wouldn't be enough. I should do a more thorough investigation.

 

[Seaweed Doc]

I may be mis-remembering (or failed to read all comments thoroughly) but I believe "death" is a possible outcome of DCS. (Not sure how likely for flying after diving, but an out come I wouldn't take lightly.)

FWIW, I use the 24 hour rule for multi-day diving. The most I "pushed" this deadline was after my instructor course. I spent a few extra days diving in Roatan, including dives to 115' and 80' the day before I flew. Another dive pro from the same shop (finishing her DM) was on my flight, and she opted NOT to do the second dive because we'd surface with just under 24 hours before our scheduled flight time. I bent the rules, figuring by the time the plane was airborne (not when it pushed back from the gate) it'd be 24 hours. I'm happy to report neither of us got DCS.

 

[Capt Jim Wyatt]

What if they unknowingly have a PFO? Is it possible then?

No AGE is an overpressure in the alveoli with a bubble getting into the bloodstream. The problem here is simply type I or II DCS.

 

[Joneill]

That's where the medical profession in general muddies things a bit . As you pointed out, technically anything that's in the blood vessels that doesn't belong there is an embolus. If venous gas emboli pass through a PFO or other shunt, they become arterial gas emboli from a medical terminology point of view. For differentiation purposes in diving injuries though, that is not considered arterial gas embolism. It's sometimes referred to as decompression illness vs decompression sickness.

Best regards,
DDM

Thanks for clarifying - same possible dangerous outcome, correct?

 

[Joneill]

No AGE is an overpressure in the alveoli with a bubble getting into the bloodstream. The problem here is simply type I or II DCS.

Understood, but it's essentially the same thing and possible outcome if I interpret the medical professional's (@Duke Dive Medicine) response correctly?

 

[tursiops]

Thanks for clarifying - same possible dangerous outcome, correct?

no