Fying/driving after altitude diving

[TheAvatar]

If you are going to surmount a mountain pass in your car, that [8000ft ascent table] is your table.

It makes much more sense simply to wait 24 hours before flying, after NDL diving, and 48 hours, after deco diving. That is what the training agencies teach (I know for sure that NAUI and TDI teach this).

There are so many accounts of Joe Diver on his way home in an aircraft ending up in a recompression chamber because he got on the plane too soon after diving.

I agree with you 100%.

I prefaced my comment with "if you are going to assume the aircraft will not depressurize" and also mentioned additional risk factors of multiday diving. Of course there are the additional risk factors of exertion, drinking, age, dehydration, etc etc etc which should encourage everyone to wait the full 24hrs for NDL diving to flying.

Fly wet, dry in the chamber!

 

[mempilot]

Bout six or seven hours. It was fun! Hard work though.

Being in shape and having an elevated hematocrit and BPG concentration helps (acclimation to altitude). If you sliced me up I'd probably have a higher density of cappilaries in my muscles too (more acclimation).

I checked out your Summit County Water Rescue Team site. Very cool! I'll bet you'd have the endurance of a pack mule at sea level.

 

[mempilot]

Guys, I don't want to press this, but for every Joe Diver that gets bent flying after diving because he/she didn't have a clue about the condition of their body, there are many of us out here that quite routinely do fly inside the 24 hour and most defineatly the 48 hour guidelines set by the training agencies (that have lots of liability).

The proof is in the pudding and the only way to know for sure is for people to push the boundries in an educated and cautious way. I do so, since I fly for a living and would not be able to dive much, if at all if I lived by the 12/24/48 rule. (wow, those numbers seem to form a pattern)

Down here in SE FL, I dive with many airline, cargo, and corporate pilots. I've been diving and then flying utilizing my own experience and proven time limits for several years now with no ill effects. And this is after 30+ minute mandatory decompression obligations.

I don't do the wet hair thing, but I don't succomb to the standard agency precaution either. Will it bend me someday? Possibly. But I have just as a high a risk of taking an undeserved hit without flying. Why, because it's theory and 'stuff' happens.

I'll say it again. Risk and reward. Some are willing to take the added risk while they prove a more envelope skirting practice, some are not. I don't discount them for being as cautious as the agencies tell them to be. That is a personal decision.

 

[triton94949]

Guys, I don't want to press this, but for every Joe Diver that gets bent flying after diving because he/she didn't have a clue about the condition of their body, there are many of us out here that quite routinely do fly inside the 24 hour and most defineatly the 48 hour guidelines set by the training agencies (that have lots of liability).

The proof is in the pudding and the only way to know for sure is for people to push the boundries in an educated and cautious way. I do so, since I fly for a living and would not be able to dive much, if at all if I lived by the 12/24/48 rule. (wow, those numbers seem to form a pattern)

Down here in SE FL, I dive with many airline, cargo, and corporate pilots. I've been diving and then flying utilizing my own experience and proven time limits for several years now with no ill effects. And this is after 30+ minute mandatory decompression obligations.

I don't do the wet hair thing, but I don't succomb to the standard agency precaution either. Will it bend me someday? Possibly. But I have just as a high a risk of taking an undeserved hit without flying. Why, because it's theory and 'stuff' happens.

I'll say it again. Risk and reward. Some are willing to take the added risk while they prove a more envelope skirting practice, some are not. I don't discount them for being as cautious as the agencies tell them to be. That is a personal decision.

I am surprised that Pete or one of his mod squad has not chimed in to give you his personal view of "risk and reward."

Between you and me, as two divers sharing drinks at a bar, talking macho and scoping out all the babes that are at the bar scoping out for themselves as well, this risk and reward discussion would also be called "pushing the limits."

As an instructor standing in front of students, the training agencies (NAUI etc) require us to teach dive students NOT to push the limits.

When is a diver no longer a student himself/herself? I suppose when that person has learned everything, has written books and been published, has become an authority themselves. A few names come to mind. Tis a short list, however.

It all depends on the environment of the conversation, I suppose. Some halls are hallowed, whereas others are not so much so.

I would always recommend a 24/48 hours guideline (NDL/Deco). The risk is that you guess wrong anecdotally, and the reward would be recompression chamber time, and all your friends knowing across the USA and the English Speaking World that you spent time in the chamber. Not that that is a bad thing, just that afterwards I doubt that anyone would listen anymore, even at the bar.

 

[mempilot]

Between you and me, as two divers sharing drinks at a bar, talking macho and scoping out all the babes that are at the bar scoping out for themselves as well, this risk and reward discussion would also be called "pushing the limits."

Risk and reward is not a macho thing but an everyday occurance in everyone's lives. "Do put some of my hard earned money into risky stocks to get the potential higher return?" "Do I drive 75 mph to get to get to work for that morning meeting because I'm running late, or do I go 65 and possibly not make it on time?"

Smokers, on a daily basis, play this game of risk and reward. Drinkers at the bar you speak of, - risk and reward. These two have life altering consequences as well. Mountain climbers vs. rock climbers, cave divers vs. reef divers, etc...

Is it 'pushing the limits'? Yes it is. But break that down a second. 'Pushing the limits' does not neccessarily mean 'crossing the limits', does it? In my course study for the kind of diving I do, I have never come across empirical data to support the 12/24/48 hour guidelines for dive to fly. I have come across CNS% decay charts, ending M values based on rate of ascent and decompression, and hundreds of other empirical charts based on formulas that in practice are still theory but have been proven enough to have a mathmatical science behind them.

Maybe I have missed the chart with the science behind the "12/24/48 laws", but I know that I can fly within that time with no ill effect because I have. Now, I do not condone just randomly picking a time and jumping in an a/c wet. That is foolish. If there isn't a proven table, then how does one know what the limit is without pushing the guidelines?

A typical dive to fly scenario for me is the following:

180' dive with a run time of 70 minutes
Out of the water by 3:00pm using a 10% concervatism on the GF% HI (I stay in the water a little longer, but lower my ending M values) I go home, hydrate, eat, and pack for the next morning. (note: no physical activity) I get a good nights sleep, and wake at 4:00am, and I'm airborne at 6:30am (commute segment of my day/I typically don't take my aircraft until later that afternoon).

My interval between diving and flying is 15 hours and 30 minutes after doing a decompression dive. If I felt bad after the dive, or in the morning when I wake up, I don't go to the airport. This hasn't happened yet, probably due to the fact that I run a conservative deco schedule, do Pile Stops, and use a slow uniform ascent rate from the first stop up. I stay well hydrated.

That is a single dive, but mandatory deco. It is well outside the 48 hours limit, and absolutely no ill effects. If I was a Joe Diver that blew the NDL on an 80' reef dive and had no idea what was going on, I'd listen to the insurance underwriters also.

 

[triton94949]

...

My interval between diving and flying is 15 hours and 30 minutes after doing a decompression dive. If I felt bad after the dive, or in the morning when I wake up, I don't go to the airport. This hasn't happened yet, probably due to the fact that I run a conservative deco schedule, do Pile Stops, and use a slow uniform ascent rate from the first stop up. I stay well hydrated.

That is a single dive, but mandatory deco. It is well outside the 48 hours limit, and absolutely no ill effects. If I was a Joe Diver that blew the NDL on an 80' reef dive and had no idea what was going on, I'd listen to the insurance underwriters also.

I would be waiting 48 hours before flying, however. Simply because that is the way I have been taught.

Since I am not a Ph.D. with a research grant for funding, since I do not have a super-computer to run algorithms on, since I do not have a fleet of divers and on-site recompression chambers to run trials with, and since I do not want to be known as the next Joe Diver fresh out of the local recompression chamber, 48 hours works well for me.

Somewhere during your IANTD class the instructor should have emphasized that individual anecdotal results are statistically insignificant compared with all the research work done by the industry. And therefore it is (here goes that infamous word oft quoted on this board and others ...) UNSAFE to run your own anecdotal trials.

 

[Dr Deco]

Hello Avatar and readers:

Tested NDLs

There have not been any testes performed on the change of NDLs with exercise at the surface. There are a couple of reasons for this.

• The observation of change of DCS incidence with activity has come to light only in the past decade with my studies at NASA concerning the difference in DCS incidence rate between ground [1-g] and on orbit [0-g].
• Many do not know of this effect or do not believe it.
• The dictum to “avoid exercise” is very general and has essentially no meaning in practical, daily life post-dive.
• This research work is not generally known by training agencies.
• one reason for this FORUM was to try to inform the diving public about this important effect – it is much more important than adding a few minutes to your decompression time.

Altitude NDLs

There are actually NDLs for ascent from the ground to high altitude. These were determined for many conditions from 1941 to 1945. The researchers found that the NDLs changed considerably when exercise was performed during the ascent (depressurization). Similar data does not exist for diving.

Testing

More likely than not, table makers would not want the tables tested under “strenuous surface activity,” since this would reduce their NDLs and produce greater restrictions when compared to other tables. This reduction in time is not a good selling point.

Dr Deco :doctor:

 

[triton94949]

...
There are actually NDLs for ascent from the ground to high altitude. These were determined for many conditions from 1941 to 1945. The researchers found that the NDLs changed considerably when exercise was performed during the ascent (depressurization). Similar data does not exist for diving.

...:

Speaking of a "Ph.D. with a research grant for funding, ... a super-computer to run algorithms on, ... a fleet of divers and on-site recompression chambers to run trials with..."

 

[saildiver]

Hard to say whether this was due to the heavy exertion (climbing) or the minor change in altitude...My vote would be for the exertion...

Jagfish-The person I'm referring to had gotten bent(Type II),went thru the chamber 2 days with full recovery,took a boat to another Island where they rested for a full 10 days, but developed minor symptoms of the bends(dismissing the symptoms at the time) each day they ascended the previously mentioned hill( painful headache,dizziness)which didn't require that much exertion-and then when they got on a plane to leave the Island,got fully bent again at around 3500 ft.,requiring 3 more days in the chamber and no flying for 1 month. Sorry ,I left out a few of the details 1st time around. I guess we'll never know for sure whether it was altitude or minor exertion that caused those N2 bubbles to reform in the blood stream at the top of that hill...Peace...Saildiver.

 

[Dr Deco]

Hello saildiver:

Delayed DCS

It is most probable that ascending the hill ten days following a dive was probably more associated with carbon dioxide and a headache than DCS and a headache.

Problems occurring after the second plane flight are also really too remote in duration to be a classical gas loading problem.

One problem is in the use of the term “got fully bent.” Technically “the bends” refers to joint pain. Since you were discussing Type II, this is neurological. Thus, what exacting occurred on the second flight? That is not to say that I can provide an answer after receiving this information. :06:

Dr Deco :doctor:

Readers, please note the next class in Decompression Physiology is September 10 – 11, 2005 :1book: