Flying after diving

[Crowley]

The recommendations, specifically, are based on flights with cabin pressures between 600 metres/2000 feet and 2400 metres/8000, or un-pressurised aircraft exceeding an altitude of 600m/2000ft. They do not apply if (cabin) altitude is less than 600m.

For single dives, a minimum pre-flight surface interval of 12 hours is recommended; for repetitive dives or multi-day diving holidays, a minimum of 18 hours is recommended. They apply to all dives, regardless of whether or not you were pushing NDLs.

Yes, these recommendations are conservative, no, I would not advise ignoring them, and I usually recommend at least 24 hours before flying after a week-long diving holiday. The risk is small, but there is always a risk.

Personally, I would advise that if you are finishing a multi-day diving holiday, you don't dive at all on that last day. If it's just a single dive, do the first one, skip the second one, and relax for the rest of the day.

Safe diving,

C.

 

[oysterdiving]

I recently taught a BA pilot and his contract states that he wasn't allowed to dive 24 hours after diving. Although PADI states 12 hours for a single dive and 18 hours for multiple dives I would be inclined to take a conservative approach.

Mark

 

[Mr Carcharodon]

They apply to all dives, regardless of whether or not you were pushing NDLs.



Safe diving,

C.

So testing an exteem case if you do two dives to one inch for a minute each you have to wait 18 hours? Would you really believe that?

This is just about gas loading relative to established dissolved gas pressure limits. Short shallow dives result in less of a gas load and can have a shorter preflight surface interval.

 

[Rhone Man]

I recently taught a BA pilot and his contract states that he wasn't allowed to [-]dive[/-] fly 24 hours after diving. Although PADI states 12 hours for a single dive and 18 hours for multiple dives I would be inclined to take a conservative approach.

I can think of pretty good reasons why pilots should have more restrictive rules than passengers. Risks may be very small, but one life vs 175 lives changes the equation.

 

[Thalassamania]

All the standard recommendations are very, very, conservative. The puddle jumper is a concern because you don't know the altitude and even if the airline gave you a best guess there's no way to know where ATC will put it in the end, could be quite a bit higher than 8,000 feet.

So if you don't need to push it ... don't.

But, for the sake of discussion, let's say you do need to push it. What's the best approach?

First of all, you should make your dives deep and short rather than shallow and long. While that sounds counter-intuitive, the reality is that on a short deep dive your controlling tissues are fast ones that also clear quickly.

Secondly, if you have oxygen ... use it. You can scrub out. If you are in USN Group N or less (NOAA is the same) you can get back to USN Group A with two hours of surface breathing 100% O2, even less time if you can deliver it in water at 18 fsw or less.

For decades I (and many others) operated, without incident, on the old USN rule that you could fly if you were a USN Group C diver or better (actually the rule was Group D, but the reality was that a new D diver, that is to say one that had just crossed over from C was OK, but a D diver about to go to E could be a problem at 8,000 feet). This is not, as I understand it, a currently accepted recommendation, I just note it anecdotaly.

 

[Crowley]

So testing an exteem case if you do two dives to one inch for a minute each you have to wait 18 hours? Would you really believe that?

This is just about gas loading relative to established dissolved gas pressure limits. Short shallow dives result in less of a gas load and can have a shorter preflight surface interval.

I am well aware of the differences, thank you, and yes, the theoretical requirements for preflight surface interval depend on gas loading and dive profiles - not to mention the personal physiology of the diver, who are mostly not the same shape - etc. etc. but since we are in the Basic Scuba Discussion forum, and most recreational divers will neither be spending 5 minutes in an inch of water nor pushing NDLs on every single dive, advising divers to abide by a widely accepted recommendation which covers all non-decompression recreational diving seems sensible, I feel.

As I said earlier, the risk is small, even if you push it, but why not minimise the risk, sip a few margharitas by the hotel pool and chat about all the great dives you had on holiday without excessive worry or speculation

Cheers

C.

 

[bygolly]

I am well aware of the differences, thank you, and yes, the actual mathematical requirements for preflight surface interval depends on gas loading and your dive profiles etc. etc. but since we are in the Basic Scuba Discussion forum, and most recreational divers will neither be spending 5 minutes in an inch of water nor pushing NDLs on every single dive, advising divers to abide by a widely accepted recommendation which covers all recreational diving seems sensible, I feel.

As I said earlier, the risk is small, even if you push it, but why not minimise the risk, sip a few margharitas by the hotel pool and chat about all the great dives you had on holiday without excessive worry or speculation

Cheers

C.

I have to agree...why push it. Relax on the last day. There are a couple of things you don't know for sure, one is the altitude the "puddle jumper" will fly to. For a number of reasons it may fly quite high even on a 20 minute flight. And the "big boy" plane is supposed to pressurize to around 8000'....what if it de-compresses at 38,000 and you are still carrying a little gas load?

 

[Downing]

Rather than try to remember the rules, I just decided long ago to refrain from diving 24 hours before my flight's due to take off.

Simple rules for simple minds.

 

[Mr Carcharodon]

Then you could get bent even if you waited a month before flying. And you would have other things to worry about.

 

[coolhandcarter]

PADI says 12 hours after one dive and 18 hours after multiple dives. But in the end you should follow your dive computers guidelines. If it says 24 hours then go with that. It's not worth a case of the bends for 2 dives.