i tried to fly out today and i ended up being bent

[DandyDon]

I didn't know that Oceanic made a computer without color codes for N2 loading. Sorry. :blush: Ok, so ascend in the Safe zone, not the Caution zone if possible - but when I go into Deco even one minute, I find that becomes impossible.

FWIW, I did freediving on the Kittiwake. It was pretty cool, since I was still relatively new at freediving, and touching the bottom at 60 or 63 feet seemed to me like a big deal. And so the entire outside of the ship was accessible to me. I was diving with a bunch of other freedivers who were all far more advanced than I, and including some national record-holders. Kittyhawk, besides being the name of the Wright Brothers' air field, is also the name of an aircraft carrier, but AFAIK, it is still afloat.

Do you know about the risks of Shallow Water Blockout?

Back to the original purpose of the thread (see, I CAN stick to the topic too!), I still don't understand how the diver could do two dives in the morning of one day and then fly out the next day at 7:20. Any time I've done dives "in the morning" I'm actually done diving around noon - which means there's no way I will have 24 hours of no fly time before I get on a flight at 7:20 the next morning. I know somebody already sort of addressed this - but even if the computers are very conservative, you'd still be tempting fate by at least 5+ hours. Are the computers THAT conservative?

Yeah, I think it was established somewhere that the did not have 22 hours before flying. I don't remember what the corrected hours were tho. Noon to 7:20am still meets the 18 hour rule tho. Who told you 24 hours?

 

[daniel1948]

Do you know about the risks of Shallow Water Blockout?

Yes. I took my first freediving class from William Trubridge, who holds the world's record for constant weight no fins. I then continued with classes from Performance Freediving International. I'd encourage all freedivers and would-be freedivers and spearos of every ability level to take a class from PFI or another reputable freediving school. Shallow-water blackout is a serious risk, but fatalities can be virtually eliminated by proper procedure, especially proper buddy procedure.

 

[kimbalabala]

Who told you 24 hours?

I guess I'm going from what my computer has indicated after a morning of dives - it seems to always say 24 hours - but it will depend on the dives won't it. Sorry - I guess I implied that you should always wait 24 hours and that simply isn't the case.

 

[Jax]

Old school said wait 24 hours before flying. Now that is reduced to 18 hours . . . though some still maintain if you have been doing multiple dives, you should still maintain 24 SIT before flying.

My computers (Uwatec, middle of the road) rarely give me that much required SIT time. DeSat (desaturation) is different - that is often 24 hours or more.

 

[DandyDon]

I guess I'm going from what my computer has indicated after a morning of dives - it seems to always say 24 hours - but it will depend on the dives won't it. Sorry - I guess I implied that you should always wait 24 hours and that simply isn't the case.

I know, computers have a 24 hour countdown so the old timers won't complain, but DAN says 18 after multiple dives. I wondered if you'd heard 24 somewhere, as DAN finds no improvement after 18 hours for no-deco diving.

Doesn't your computer have a countdown timer to clear N2?

 

[Thalassamania]

Old school said wait 24 hours before flying. Now that is reduced to 18 hours . . . though some still maintain if you have been doing multiple dives, you should still maintain 24 SIT before flying.

My computers (Uwatec, middle of the road) rarely give me that much required SIT time. DeSat (desaturation) is different - that is often 24 hours or more.

Actually Jax, "Old School" was you can fly if you are in USN Group D or less. There was a problem with this, while a new diver, just crossed over from C was fine to goSN to 8,000 feet, a diver who was in D, but close to E was not. This resulted in some bends cases and the recommendation that a 24 hr SI be suffered through prior to flying. I can't tell anyone what to do, everyone is different, but I have flown using the Group C rule many, many times without incident.

 

[kimbalabala]

Doesn't your computer have a countdown timer to clear N2?

We plan our travel so that we have more than 24 hours from our last dive until we fly (i.e., last dives in morning and fly out the next day at 5 p.m.), so I haven't had to keep track of how many hours I have to wait. I know I'll be clear to fly and don't worry about it. I wouldn't be comfortable planning a dive that had the potential to bump up against my no-fly time and I don't have the requisite knowledge to split hairs to get in one more dive "just under the wire" - can't afford to take the chance and have to re-book for a later flight, so dives are conservatively planned around the outbound flight. But yes, our computers do have a countdown.

 

[daniel1948]

While I do not dispute the 18-hour rule, I, too, like to plan my travel to give me 24 hours. I love snorkeling, and sometimes will snorkel, rather than dive, on the last morning.

 

[GrumpyOldGuy]

We plan our travel so that we have more than 24 hours from our last dive until we fly (i.e., last dives in morning and fly out the next day at 5 p.m.), so I haven't had to keep track of how many hours I have to wait. I know I'll be clear to fly and don't worry about it. I wouldn't be comfortable planning a dive that had the potential to bump up against my no-fly time and I don't have the requisite knowledge to split hairs to get in one more dive "just under the wire" - can't afford to take the chance and have to re-book for a later flight, so dives are conservatively planned around the outbound flight. But yes, our computers do have a countdown.

There is nothing wrong with being conservative.

Most of us split hairs all the time on dives over 60ft and run NDL down to within a few minutes without issue. Many of us dive at altitude with the necessary adjustments to the tables. To do all this and then think that flying after diving requires a simplistic 24 hour count down does not make sense. If you can understand basic tables the leap to understanding the NOAA ascent to altitude tables is not a big leap.

 

[Blastman4444]

Maybe this is where the 24 hour rule came from which computer manufactures kept it the same. I found this It's in the FAD workshop in 2002 http://www.diversalertnetwork.org/research/projects/fad/workshop/FADWorkshopProceedings.pdf

To simplify these guidelines and make them safer for recreational divers, DAN proposed
a wait of 24 hours before flying after either single or repetitive no-stop dives. The DAN
guideline was revised in 1991 in response to an appeal from the recreational diving
community who argued that the low DCS incidence did not justify a 24-hour preflight
surface interval for all types of diving. At the time, DAN data contained 31 cases among
an estimated 2 million divers who flew during the period 1987-90, for an overall
incidence of 1-2 cases per 100,000 divers. The revised (and current) DAN guideline
recommended at least 12 hours after a single no-stop dive and longer than 12 hours after
repetitive dives, decompression dives or multiple days of diving (16).