18 hour wait before flying

[DiveNav]

Could you relate this to the question at hand?

The OP was inquiring on how long to wait before flying after diving ..... and the response is ..... "it depends".
If a diver goes on a week long dive trip during which he/she does multiple - and long - dives each day - and maybe some night dives too, at the end of the week the slow compartments could be substantially loaded.
That is why some computers have the De-sat timer

 

[Herk_Man]

On the contrary, the odds of him being in another one are astronomical

Well, unless he's a pilot

As a military/commercial aviator, I have to disagree with your final phrase there. But adding the word "bad" to it might make me concur.

 

[Thalassamania]

Seriously, three.

I was not the pilot.

Two were with small planes, one in a DC-3, all in Central America. All three involved a loss of power and a partially successful emergency landing (well ... completely successful in that no one died, but the planes were totaled).

I was doing a lot of flying back then and incidents of this sort were, at least amongst the folks I knew who were doing the same, were not infrequent.

 

[Tortuga68]

As a military/commercial aviator, I have to disagree with your final phrase there. But adding the word "bad" to it might make me concur.

Maybe we can compromise and make it "unlucky"??

The OP was inquiring on how long to wait before flying after diving ..... and the response is ..... "it depends".
If a diver goes on a week long dive trip during which he/she does multiple - and long - dives each day - and maybe some night dives too, at the end of the week the slow compartments could be substantially loaded

You specifically mentioned a half time of 635 minutes, which is about 10.5 hours. So my question is, what is the relationship between this and the No Fly time?

 

[Gerbs]

Decompression Theory 101, abbreviated:

You load up on nitrogen. Different bits of you at different speed. For calculation purposes bits that are similarly quick in absorbing and releasing nitrogen are grouped in compartments.

Compartments have a maximum of nitrogen in relation to the pressure surrounding them, before Bad Things Happen. Let's say about .4 ata (for the sake of calculations; do not use this to plan your dives!!). So... You are at 1 ata, and your highest compartment is at , let's say 1.4 ata equivalent nitrogen load. Oh, remember, at sea level, your nitrogen loading is .78 ata (air 21% O2, 78% N2, 1% rest)

So... Assume that you have been diving a lot, and are skimming the NDLs (bad practice, tbh), and you load up your 10.5hrs compartment to the point of where you can *just* surface before issues start. Cabin Altitude we are going to assume at .6 atm (4000m/12k ft altitude), while you have just climbed out of the sea at 1 atm.

Now, in 10.5 hrs the slow compartment is going to be from it's maximum to halfway to sea level nitrogen levels. This gives you 1.09 atm. You want to risk a 1.09-.6 = .49 atm difference? 20% over what you can normally be expected to tolerate...

You wait another 10.5 hrs. Now, your level is (1.09+.78)/2 = 0,935. Gives you .335 over your cabin altitude. .4 you can tolerate... Let's go Fly!

So... 21 hrs before safe flying!

Ok, to load up your 10.5hrs compartment to 1.4 ata, you need to basically go into saturation diving.... so effectively, you won't have this long to wait in practice.

I personally am of the opinion that longer wait times are not detrimental to post diving safety!

Gerbs - plans for 18-24hrs/computer desat whichever is longer, and is still perturbed that basic decompression theory is not included in OWD, as all dives over 10m/33ft are decompression dives (albeit where surfacing at a low enough rate stops the bad things happening without needing stops)

 

[Blackwood]

Not entirely accurate, but decently stated.

I personally am of the opinion that longer wait times are not detrimental to post diving safety!

Of course they are not. I don't think anyone would suggest they are. So the question becomes: what's reasonable, and what's just silly?

 

[Tortuga68]

Indeed