23 Hour Surface Interval Before Flying

[Rogersea]

We are headed to Kona next month on a trip with my in-laws. The days we can dive are somewhat limited and I'd really like to do a morning 2-tank the day before we fly home at 1:05pm. The shop says we'll be back by 1:30pm, giving us about a 23.5 hour surface interval before flying, more likely closer to a full 24 hours once you consider the ride back.

This is making my husband a little bit nervous. Our computers count down no-fly time from 24 hours since the last dive. My research online shows 18 hours after diving multiple days. We could even stay a bit shallower on that last day of diving, maybe say a max of 60 feet, to reduce the amount of nitrogen we take in.

I'd love to hear your thoughts on this. Thanks!

In my and most folks opinion that is an adequate period of time between no decompression dives and flying.... The problem really becomes how uncomfortable your husband is with the idea of flying 23.5 hours after diving, and if by having that dive profile he becomes a bad travel partner.... If you suspect he will be hard to travel with because of it,maybe you could do one dive in the morning and one afternoon snorkel...

I personally would have no problem with doing two no-deco dives in that time frame...

Cheers,
Roger

 

[Doc]

Whose recommendation? Not DAN's or any other recognized dive organization I know of. DAN has had the 18 hours after multiple days of diving for 10 years that I can remember.

Many dive computers have 24 hour countdowns but I suspect that's just to sell computers to divers who have heard some claim that 24 hours was safer - even tho there is no support for those claims as DAN studies found no real increase in safety by padding the extra 6 hours.

It's more a case of 180° opposite the case being true.

This is where a sense of history comes in. The technical side of the "industry" has warped an existing and long-held theory to conform to the needs of the travel side of the industry. Resorts were having a hard time telling (enforcing?) guests to stay out of the water -24hr before take-off time.

It is a simple matter for a programmer to alter the no-fly blinkie thing on your expensive toy. When you buy one, you can essentially "shop for an opinion" by selecting the no-fly algorithm upon which you are willing to gamble your life. You think computer manufacturers aren't aware of these discussions? That's why they build restrictive programmable tech computers (they're usually black or made of 3 pounds of of solid brushed aluminum) or they also offer loosey-goosey hockey-pucks with green-yellow-red pixels for us warm-water-pretty-fish dweebs.

It's even caused liability-wary Certifying Agencies to alter their printed materials and training books. Don't think they're under pressure for the travel side?

Like all 180° opposites, let's look at the other end as well.... Is it safe to dive after the dehydration of flying?

Resorts do not want to tell guests that they should fly-in, then sit on shore and hydrate (non alcohol) upon their arrival afternoon. They do not want guests to be denied stepping off the transfer bus from the airport and onto a dive boat. Many guests simply can not wait and oh- what a selling point (story to tell back home). Either that, or there's a welcome rum-punch party. That makes perfect sense.

There is no real study about hydration and DCS either- mostly because it would be monumentally difficult to track. And remember, the "industry" isn't looking for "wrong" answers~ they want divers.

I have found that many visitors who are concerned with hitting the water immediately upon arrival, or pushing the no-fly limits- these are generally people who should have been more motivated to do every dive offered during their short stay in paradise~ versus sitting out a day because of shopping or a hangover (commonly referred to as a tanning day).

 

[DA Aquamaster]

Whatever rule or computer, or table... Nowhere you look you will find a rule of not flying more than 24 hours.

It may have changed since 1987, but the US Navy required 48 hours between diving and flying for it's pilots.

Of course that was based on some worst case assumptions such as sudden loss of pressure at 40,000' etc, not the fairly sedate 8,000' cabin altitude of an airliner.

----

But I completely agree that a 23.5 hour surface interval after a couple of 60' pretty fish dives is not an issue.

For liability reasons no one will say the risk is zero, but in the real world, the risk of DCS caused by a 23.5 hour off gas period before an airline flight will be a lot less than the risk of shark attack, the dive boat sinking, getting injured in the cab ride to the airport or the OP slapping her husband upside the head for being a ninny.

And as noted above, the reality is if you are counting 23.5 hours from the time you get back to the shop, your actual surface interval prior to flight will be in the 25-26 hour range.

 

[cascas]

or the op slapping her husband upside the head for being a ninny.

lol :d

---------- Post Merged at 02:52 PM ---------- Previous Post was at 02:48 PM ----------

It may have changed since 1987, but the US Navy required 48 hours between diving and flying for it's pilots.

Of course that was based on some worst case assumptions such as sudden loss of pressure at 40,000' etc, not the fairly sedate 8,000' cabin altitude of an airliner.

I have no knowledge on things concerning US Navy, but I would imagine that comparing pre 1987 US Navy pilots and nowadays commercial airline passengers is not a real fair comparison

 

[DivemasterDennis]

First, I think we should commend the OP for being cautious and being safe. She has sought out appropriate information (all of which says its fine to dive and fly and planned) and also input from more conservative planners. I will admit that when Debbie and I dive multiple dives for multiple days we have a a no dive day the day before flying, but in part that is to really clean gear well and make sure it is all bone dry so we don't pay overweight fees for packing water in our neoprene. We are also nearly 60 years old, and the added risk factor of age makes us a little more conservative on dive and fly planning.
No need for argument here. Divers need to be comfortable with their dive and their travel plans. No need to slap your husband or leave him either ( at least not for raising the issue- maybe some other reason). But on the strength of all responses, he should relax and enjoy the diving and flying as planned.
DivemasterDennis

 

[DandyDon]

* For dives requiring decompression stops, there is little evidence on which to base a recommendation and a preflight surface interval substantially longer than 18 hours appears prudent.

I often dive in situations where if I had to call/end the dive early I would have a deco obligation. Like Devils throat, or even Speigel Grove. So I fall under the above guideline and I take the no fly rule seriously. That is a DAN recommendation which you indicated you Liked.

I rarely fly and dive in the same 48 hours. This is what I do. You do what you want.

Ok then, when you said "The recommendation is a 24 hour no fly time which assumes you have been doing multiple dives over many days," you meant for deco dives - as there is no know DAN or agency recommendation like that.

I doubt they'll do any deco...

 

[Kryssa]

No deco... generally we dive between 30 and 80 feet and always watch our computers for NDL

Thanks all for your thoughts. I'm diving Saturday for sure

Sent from my Galaxy Nexus using Tapatalk 2

 

[endurodog]

.
No need for argument here. .
DivemasterDennis

Wait this is scubaboard, haaaaaaa

Kudos to the OP for getting info instead of going on hope.

 

[Thalassamania]

Manage your ascents, don't exceed 10 m/min ( 30ft/min) during the deeper part (> 15 m/45ft ) of your dive and 3 m/min ( 10 ft/min) in the shallower part (<10m /30ft). And you will be fine flying 18 hours after your dive...

Yes, 18 hrs should be fine, even a bit less I suspect.

The pressure drop in a pressurized air-plane cabin equals 2 m / 6 feet of water pressure. That really is nothing much to worry about. Providing the pressure doesn't suddenly drop.

With sufficient time to off-gas sure, but the drop in pressure from sea level to 8,000 feet is more than enough to get one bent under the right circumstances, it is not "nothing much to worry about."

I know about technical divers that do dives that exceed 50m/150ft with runtimes of over 5 hours (talking about deco dives ) who will pack their gear, drive over to the airport and take off within hours after surfacing. Off course that does not mean anyone can do this. These guys are in super physical shape, know deco like no one else, AND manage their ascents.

Sure, I've dove those sorts of schedules and flown without incident. The gas mix has a lot to do with it as does the use of oxygen for decompression. Pointing to mixed gas dives with oxygen decompression and then drawing conclusions about flying after no-decompression air dives is, as they say, "farm animal stupid."

Cutting short no-fly time by 0,5 hours after recreational dives ?... ? Not a problem !

In this case, no problem, in other cases cutting a half hour off could be.

 

[NCadiver]

Make sure you are well hydrated and use 36% mix for your dive.