Skipping surface intervals - DIR or not?

[Doc Intrepid]

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"A little knowledge is a dangerous thing..."
Alexander Pope (1688-1744)

Elvis has left the building...

 

[StSomewhere]

If that were even remotely close to true then a diver could do a 100' dive, make a 10 min. ascent and then jump on an airplane with no worries.

I've had discussions with other DIR instructors who say the same thing, and follow it up by actually doing it.

If you've offgassed correctly (up to the 8000 ft level), then going on an airplane that's pressurized to 8000 ft theoretically shouldn't be a problem, right? OTOH, if you're already bubbling (say, the RDP bend-and-mend model) then getting on an airplane is probably a collosally bad idea.

Charlie, dude, lose the sarcasm. You've learned it one way, that doesn't mean its the only way. Accept that the world isn't flat for eveyone, especially when you are in the DIR forum. :roll:

 

[Spoon]

I've had discussions with other DIR instructors who say the same thing, and follow it up by actually doing it.

although many have said that its ok im quite hesitant to test it on myself when themajority say that the min no fly is 24hrs. if that were the case then id be able to bang out more dives from my dive trips.

 

[clgsamson]

If you're insured by DAN, ask DAN about breaking the no-fly rule.

 

[Jai Bar]

I've had discussions with other DIR instructors who say the same thing, and follow it up by actually doing it.

If you've offgassed correctly (up to the 8000 ft level), then going on an airplane that's pressurized to 8000 ft theoretically shouldn't be a problem, right? OTOH, if you're already bubbling (say, the RDP bend-and-mend model) then getting on an airplane is probably a collosally bad idea.

Charlie, dude, lose the sarcasm. You've learned it one way, that doesn't mean its the only way. Accept that the world isn't flat for eveyone, especially when you are in the DIR forum. :roll:

First of all, why trust your dear safety- not to say life- to an assumption that jets allways keep pressurized to 8000ft level? Isn't it better to keep all safety factors controlled by yourself?

I really don't know much about DIR in general, and nothing about how they calculate decompression profiles in particular. But I do know that there are not many physical models that are beeing used by the diving comunity in order to estimate the amount of inert gasses dissolved in our tissues in order to avoid decompression sickness (similar models are used in various fields of science and life, by the way). I have a slight suspicion that also the DIR community uses one of these models in order to generate dive profiles, tables, SI's etc. just as what you call "RDP bend-a-mend model". There isn't really much difference, only that divers using RDP usually dive on air and/or Nitrox, they don't do deco stops on 50%/100% O2, and there is nothing wrong with that.

These models can predict- to some extent- whether or not it is safe to step "hair dripping" into an airplane. Sometimes it is possible, sometimes it is not. Sometimes the waiting can be accelerated (100% O2, for example), sometimes it cannot. If one offgassed correctly usind PADI's RDP, he will be able to get into an airplane too.

 

[StSomewhere]

Jai Bar,

The fact is that DIR instructors believe they can deco well enough to get on a plane after a normal dive, and then back it up by doing so. The DIR concept of deco is a different beast from what the other agencies preach. Even for recreational dives, the parameters are different. I'll admit flying with wet hair is more than I'm ready for at this stage, but you have to admit there is power in thier actions.

You're a physicist and instructor, how well do you trust your deco plan?

 

[Web Monkey]

Decoing to 8,000 ft is just fine, assuming nothing happens that puts you higher than 8,000 ft.

Since the plane actually flies at 30,000 ft +, the DIR instructors you mention are trusting their lives to a control in the cockpit, and betting that nothing Bad happens during the flight to make the plane lose pressurization.

Terry

Jai Bar,

The fact is that DIR instructors believe they can deco well enough to get on a plane after a normal dive, and then back it up by doing so. The DIR concept of deco is a different beast from what the other agencies preach. Even for recreational dives, the parameters are different. I'll admit flying with wet hair is more than I'm ready for at this stage, but you have to admit there is power in thier actions.

You're a physicist and instructor, how well do you trust your deco plan?

 

[cmalinowski]

Decoing to 8,000 ft is just fine, assuming nothing happens that puts you higher than 8,000 ft.

Since the plane actually flies at 30,000 ft +, the DIR instructors you mention are trusting their lives to a control in the cockpit, and betting that nothing Bad happens during the flight to make the plane lose pressurization.

Terry

Your trusting a lot more than just the pressurization

Who the heck was this bernoulli guy anyway? I think it's all magic... just like decompression

Chris

 

[cbfin]

Decoing to 8,000 ft is just fine, assuming nothing happens that puts you higher than 8,000 ft.

Since the plane actually flies at 30,000 ft +, the DIR instructors you mention are trusting their lives to a control in the cockpit, and betting that nothing Bad happens during the flight to make the plane lose pressurization.

The day before yesterday, an Eskimo plane lost cabin pressure while leaving Seattle (I believe twice.) You just never know.

I would also advise against using what a GUE instructor has done as a basis for what everyone can or should do. I don't know about you, but I'm no where near the physical or physiological level that my instructor was (is). I'm not a vegetarian, I enjoy beer, I don't exercise daily, and I guarantee no one has referred to me as having an athletic build since high school.

It is alright to look at what they've done and agree that it is possible. Then evaluate yourself and adjust according. If you are in just as good of shape, have as much experience, and do the same dive conditioning (tons of deep repetitive dives), then great. But just because JJ can complete a 15 hour dive exploring over 3 miles into a cave system at depths exceeding 300' doesn't mean I can. (It is impressive to know that it's possible though.)

I would also add that you may want to error on the side of conservatism as people who don't know as much as they think, usually find out they were wrong the hard way.

 

[*Floater*]

I believe that my instructor believed that people who got bent on airplanes were already bent when they got on.

These guys are definately showing what's possible. I'm not going to try to replicate what they do right away, but I will apply their teachings with added conservatism, see how I feel after and then take it from there.

I've been told that it's possible to tell whether you've off gassed properly by how you feel; are you tired and beat after diving? Do you feel out of breath when lifting tanks after a dive? I think I've even felt some slight tingling during my early diving carreer, though at the time I didn't make the connection with possible DCS. If you are in touch with your body, then you should be able to tell before you end up at the chamber.