Question Diving before flight

[FishWatcher747]

To the OP, you are very unlikely to do a 60 foot night dive out of Key Largo. There are loads of 30 foot reef dives in Key Largo and that is probably where your outfitter will take you. There is the Benwood wreck at 45 feet. Then there is the Spiegel Grove, Duane and Bib which are about 110 feet which I am confident that your outfitter is not taking you on a night dive.

So 30 foot reef dive for probably 45 minutes ( time limit probably set by your outfitter) with 32% Nitrox you will be nowhere near NDL and at extremely low (not zero) risk.

 

[hilljo88]

My personal decision is to wait 24h....but then I prefer that to 18h in all cases anyway.

Same. Seems like a minimal effort to plan surface activities for last day in return for safety margin.

 

[Beau Holden]

Hello! My 12-yr-old and I are newly certified OW divers and are booking our first dive trip to the FL Keys. We’re getting our nitrox certification in a few weeks so that will be complete before our trip. I have questions on what dives we should be able to do safely without violating no fly limits. Would this be safe?

Day 1: afternoon shallow (< 60 ft) 2-tank dive with 30% EANx
Day 2: no dives planned
Day 3: evening shallow 1-tank dive with 30% EANx (done before 6:30 pm)
Day 4: Fly home at noon, and if it matters we live at 5300 ft (arriving 8 hours after takeoff as there’s a layover)

We'd be right at that 18-hour mark between the last dive and flying out with a full day off from the previous dives. I just don’t want to push it! Does this seem safe?

Me, I would dive days 1 and 2 (mornings, two tank dives) and take day 3 off and fly out on day 4.

 

[Rob9876]

Seems to me that with about 48 hours between the shallow Day 1 dives and the Day 3 dives, for all practical purposes those Day 1 dives are basically gone and we're talking about a single day, single tank, shallow dive (on EANx, FWIW). So, for DAN (USA at least) that's a 12 hour no-fly minimum recommendation.

There's nothing wrong with any individual choosing to go beyond that with 18 hours, 24 hours, or more if they want, but the proposed schedule seems squarely within DAN recommendations.

The only wrinkle is arriving at OP's home at 5,300 feet approximately 26 hours after that single tank dive -- having first returned fairly near sea level in D.C. for a layover. From posts above it seems like the hours of airplane flights (to which all of us are exposed when we travel) will likely have a "cabin altitude" greater than that -- so I'm struggling to see how OP's schedule really has any more risk than the vast majority of divers accept (within DAN's guidelines).

Again, nothing wrong with deciding to wait longer, and there's almost always a "non-zero" possibility of Decompression Illness. It'd be great if someone from DAN or similar organization would weigh in, but as for me personally I'd have a hard time telling someone that they should re-arrange their trip or skip that dive under these circumstances (disclaimer: I'm not a medical doctor or any type of DCI expert).

 

[crofrog]

All the research presumes the diver is returning to sea level at the end of the altitude excursion.
You are playing with fire if you fly to Denver instead of sea level.
Wait 24h, at least.

The navy ascent to altitude tables don’t assume that.

Pressure group K which would be 63 minutes at 60ft requires 15:55 minutes for an ascent to 8000ft and 7:41 minutes for an ascent to 5000ft, and that’s for an air dive.

Nx30 further reduces that risk, although if you’re only going to 60ft I’d use a richer mix if you’re worried about it

 

[FreqFlier]

My 12-yr-old and I are newly certified OW divers

I'm yet to see freshly minted OW divers on a night dive... Many dive ops will raise a red flag here to begin with.
Other than that common sense would say - gimme your depth and bottom time on you last dive. This will presumably allow to get to N2 sat levels and subsequently SI's before flight. DAN or no DAN - math will be relatively easy.

 

[DogDiver]

Everyone has seemed to miss one very important issue. The 12 year old diver. For an average adult the time period between diving and flying isn’t an issue. But I would be very hesitant to put a child in the air within 24 hours. No studies have been conducted on nitrogen under pressure in children. I wouldn’t risk it.

 

[L13]

Everyone has seemed to miss one very important issue. The 12 year old diver. For an average adult the time period between diving and flying isn’t an issue. But I would be very hesitant to put a child in the air within 24 hours. No studies have been conducted on nitrogen under pressure in children. I wouldn’t risk it.

Where did you get 24 hours? If no studies have been done.

/s Since no studies have been done, is any time frame safe? Lets wait 72 hours! /s

/s For that mater, I don't think much research has been done specifically on 55 year olds. Maybe it isn't safe for me to fly within 96 hours after diving either! /s

I hate this thing that is going around where if something specific hasn't been research, we assume we know nothing and throw up our hands in panic, or just as bad, arbitrarily pick some other number, or random idea.

In this case, you will never get the research. No one is going to risk their careers doing this kind of research on 12 year olds.

 

[Kendall Raine]

Where did you get 24 hours? If no studies have been done.

I hate this thing that is going around where if something specific hasn't been research, we assume we know nothing and throw up our hands in panic, or just as bad, arbitrarily pick some other number, or random idea.

Agreed.

Sounds a bit like such topics as Gradient Factors, depth averaging, flying after diving, IPE, pre-post dive exercise, etc. Also why dive computer implementations are padded to be more conservative than the underlying algorithms-not just lawyers being lawyers but recognition that decompression is a complex and poorly understood process. Just look at high variability of Doppler scores for the same diver/dive profile. It’s not quite “pick whatever number you want” but it does seem that way sometimes.

I think all divers just need to be informed on latest thinking and wary of spurious precision in all this stuff (i.e. the line between safe and unsafe is a mile wide and if we really wanted to be safe we wouldn’t dive at all-just sit on the couch and watch reruns of I Love Lucy).