23 Hour Surface Interval Before Flying

[Kryssa]

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!

 

[jmneill]

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!

23.5 hours, after a two tank dive to 60'? I don't think he has much to be nervous about. I'd be more worried about what peanut substitute they would be serving on the plane.

 

[Scuba_Noob]

If he's that nervous, you could do a couple of extremely conservative dives, do one dive only, or don't do the dives at all. However, 23.5 hours is beyond the recommended surface interval before flying, so there shouldn't be anything to worry about if you do two normal dives. Also, if the shop says you'll be back by 1:30pm, you'll probably be out of the water quite a bit earlier.

 

[mathauck0814]

You'll be fine.

 

[kf7lze]

If he's diving with a computer it might even calculate a de-saturation time, mine displays an airplane symbol and a countdown timer after a dive once you're out of the water.

 

[jar546]

What does the dive table say that you learned on?

 

[Hawkwood]

It seems that the majority of the computers do default to a 24 hour "no-fly" time.

However, the current medical views on flying after diving are as you found: 18 hours after a repetitive dive, or multiple days of diving, or 12 hours after a single dive.

From DAN's website:

Revised Flying After Diving Guidelines for Recreational Diving - May 2002
The following guidelines are the consensus of attendees at the 2002 Flying After Diving Workshop. They apply to air dives followed by flights at cabin altitudes of 2,000 to 8,000 feet (610 to 2,438 meters) for divers who do not have symptoms of decompression sickness (DCS). The recommended preflight surface intervals do not guarantee avoidance of DCS. Longer surface intervals will reduce DCS risk further.

• For a single no-decompression dive, a minimum preflight surface interval of 12 hours is suggested.
• For multiple dives per day or multiple days of diving, a minimum preflight surface interval of18 hours is suggested.
• 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.

 

[diverrex]

I wouldn't give 23.5 hours a second thought. After reviewing Navy tables and doing other research I am quite comfortable flying 18 hours after doing 2 morning dives up to 60 feet. I probably do each dive slightly more conservative than normal, meaning a multilevel ascent after 30 minutes, 5 minute safety stops and Nitrox.

 

[redacted]

Why don't you do the dive and leave him behind if he is unsure.

 

[Kilili]

"24" is merely a number that yields a high probability of a favourable outcome. It's origin is experiential, not hard science, and using it does not guarantee you will not experience DCS.
As always, use your best judgement, whether diving or picking a husband.