"no fly" time

[Walter]

Well, you did lead with your chin.

Seriously, odds are unless you are pushing it, you'll be fine following almost any of the rules mentioned. I never had a problem when I used the D group rule. One of my buddies, when he was in the military, frequently was flown while still dripping wet. He never had a problem. OTOH, none of the rules are perfect. Flying after diving always poses a risk of DCS. The more conservative the rule, the less risk. I like being very conservative.

 

[limeyx]

FAD trial info is here. The surface interval is 8 hours now so the dive and flight are in one (long) day.

We have other fun ones as well...

So if I am understanding this correctly, I have to fly myself to NC, get $120 and have to stay one night ?

But it seems like this is just the dry portion -- I am more interested in actually getting in the water, doing a deco dive and seeing if I get bent ascending to 8K

for that, I'd cover the cost of the flights myself and wouldnt take the $120 if it would be used to help develop or analyze flying after diving requirements.

Maybe I should start my own anecdotal survey project ...

 

[stiebs]

What kind of plane?

I think it was a Beechcraft Kingair. The flight was also low altitude, at around 3000ft.

 

[stiebs]

Guess post #12 was too 'technical'.

I followed your links, and it didn't look like the two were related. The link to DAN research the page you linked to referred to anecdotal survey results, not controlled tests.

 

[Thalassamania]

All I can really say is that I used (and use) the old U.S. Navy approach to flying after diving since 1970 or so. I've made perhaps 100 flights using those rules without incident. I have always been meticulous about ascent rates, I been scrupulous about my decompression, I have used deep stops since long before they became mainstream (and included the time in bottom time), I have always made a safety stop (and included the time in bottom time) to cover errors in time keeping or on the off chance that I was not looking at my depth gauge at the deepest part of the dive. I have long been a strong believer in oxygen ... green gas is good gas.

I've watched over the years as rules became more and more restrictive. When NAUI moved the U.S. Navy tables over one column I raised holy hell, their explanation was that it compensated for divers screwing up and was legally defensible. I've often felt that many changes in the rules were not based on good science, but rather on a poor opinion of how well human beings perform and what the lawyers will say and do.

I do not recommend that others emulate my practices, susceptibility to DCS is an individual thing. I know people that are nearly unbendable. I may be one of them, I don't know because my diving has always been conducted in a risk-adverse fashion, so I've never tested it (with the possible exception of the flying after diving thing which came about just through the history of it all).

It's like Bob Dylan said, "To live outside the law you must be honest."

 

[Bismark]

Walter, I played rugby so what do you expect......

Speaking from personal practise, I tend to be more conservative than my argument would lead you to believe. However, I really don't like the regular application of conservative principles simply because they are designed to protect the lowest common denominator. I would rather have full disclosure and then look at the evidence and science and make the decision for myself. We are not all socialists here in Canada........

In a nutshell, flying after diving in an airliner pressurized to 8000' is similar in concept to being able to reduce the pressure a further 8 or so FSW after climbing out of the water. I still am unable to wrap my brain around the fact that this is very risky in a recreational setting. As long as you follow say, navy tables, your entire gas load will still fall within pretty conservative. The pressure differential at 8' is pretty small then. Moreover would it be safe to say that most of the gas load would be slow tissue loading, so would "most likely" be something to cause type I and not type II DCS?? All ears here......

 

[Bismark]

All I can really say is that I used (and use) the old U.S. Navy approach to flying after diving since 1970 or so. I've made perhaps 100 flights using those rules without incident. I have always been meticulous about ascent rates, I been scrupulous about my decompression, I have used deep stops since long before they became mainstream (and included the time in bottom time), I have always made a safety stop (and included the time in bottom time) to cover errors in time keeping or on the off chance that I was not looking at my depth gauge at the deepest part of the dive. I have long been a strong believer in oxygen ... green gas is good gas.

I've watched over the years as rules became more and more restrictive. When NAUI moved the U.S. Navy tables over one column I raised holy hell, their explanation was that it compensated for divers screwing up and was legally defensible. I've often felt that many changes in the rules were not based on good science, but rather on a poor opinion of how well human beings perform and what the lawyers will say and do.

I do not recommend that others emulate my practices, susceptibility to DCS is an individual thing. I know people that are nearly unbendable. I may be one of them, I don't know because my diving has always been conducted in a risk-adverse fashion, so I've never tested it (with the possible exception of the flying after diving thing which came about just through the history of it all).

It's like Bob Dylan said, "To live outside the law you must be honest."

I have only been diving since '82 and without your scientific aspect to it, but that pretty much sums up my experiences as well. I can't get past making things more restrictive to compensate for lack of knowledge or skill is just not the way to go.

 

[Thalassamania]

I think it was a Beechcraft Kingair. The flight was also low altitude, at around 3000ft.

Interesting, I just looked it up. The Kingair can maintain a differential of 6.6 PSI, which means sea level pressurization to a little over 15,000 feet.

 

[Charlie99]

In a nutshell, flying after diving in an airliner pressurized to 8000' is similar in concept to being able to reduce the pressure a further 8 or so FSW after climbing out of the water. I still am unable to wrap my brain around the fact that this is very risky in a recreational setting. As long as you follow say, navy tables, your entire gas load will still fall within pretty conservative. The pressure differential at 8' is pretty small then. Moreover would it be safe to say that most of the gas load would be slow tissue loading, so would "most likely" be something to cause type I and not type II DCS?? All ears here......

It might help you get your mind around things if you looked into altitude DCS a bit. (Not DCS in divers that go to altitude, but DCS in persons that start at sea level saturation and go to very high altitudes).

Going to 0fswa is only a change of 33fsw from sea level, but you will most assuredly have DCS long before you get to 0fsw.

================

There is also a big difference between normal recreational diving with air or relatively low FO2 nitrox vs. decompression diving where the final stops are on 100% O2. Again looking at parallels in the aviation world, the final deco stops on O2 are analogous to the prebreathing of 100% O2 that is done before HALO parachute dives and before space walks from the shuttle. If you look at the pressure differences involved in space walks and HALO they aren't very great. What is large is the pressure ratios.

The recreational diver doesn't have the advantage of breathing a mix that has 0psi of N2.

 

[Gene_Hobbs]

I followed your links, and it didn't look like the two were related. The link to DAN research the page you linked to referred to anecdotal survey results, not controlled tests.

Excellent, this is great feedback. I spend so much time looking at this stuff that I miss the obvious. --especially this topic since I have been a part of it at work (Duke) and on the side (Rubicon).

The workshop (first ref) contains technical details from the trials. The third paper (Vann et. al.) and sixth paper (Pollock et. al.) also cover details from this data set. I would guess that the article you discussed was written by Pollock...

This page started out as notes for me but has turned out to be a useful guide so... How should we word these to make it more obvious that this work is related and the page more useful? (Can't just group it under DAN since they have not paid the bill for all of this work.)

limeyx - Believe it or not we have had a subject fly here from LA just to do the study (way back in phase one). Quite a personal expense to undertake but he felt like the experience and study outcomes would be worth it. (he still teaches out there...)