Flying After Shallow Dives

[grouchyturtle]

Dear Scuba Board Readers:

Shallow Dives

You cannot get DCS from shallow dives because you have not taken in a sufficient dose of nitrogen to form a sufficient volume of gas bubbles in the critical tissue (probably tendon and ligament). It is not a decompression stop because you are not eliminating dissolved gas from a deeper depth. You are on gassing an insufficient (for DCS) amount at 20 feet. The time limit at any given depth is the NDL.
Dr Deco :doctor:

Then would it also be safe to fly after a shallow dive?

 

[scubadobadoo]

Good question.

 

[whalerkyle]

Safe? Nothing is safe.
Why risk it?

Kyle

 

[grouchyturtle]

Ok...safer?

Just because I asked the question doesn't mean I'm planning on doing it.

 

[DandyDon]

This is not covered in Recr Diving, that I know of. The NOAA dive manual has expaded information on this. If you don't have the book, you don't have the info, therefore don't know where you are, therefore probably shouldn't.

 

[whalerkyle]

Just sit near the emergency oxygen tank, and ask to use it during the flight.

 

[grouchyturtle]

This is a serious question!

This is a medical forum. Just because a question is asked here doesn't mean that someone will take the info they receive and do something stupid.

If you look through the Dr. Deco forum I'm sure you will find plenty of other threads asking questions simply out of curiosity and or to better understand the effects of diving on your body, and DCS, and blah blah blah etc...

At least scubadobadoo is interested in seeing what Dr. Deco or one of the other doctor's answer is.

 

[DepartureDiver]

Then would it also be safe to fly after a shallow dive?

Not necessarily. Even though enough nitrogen has not been ongassed to cause DCS while surfacing after a "shallow dive" (i.e. 20' or less), it does not mean that further reducing the pressure would not result in DCS. However, if we're talking dives to 20' then there would probably be no need to have a long wait before flying.

 

[Charlie99]

Then would it also be safe to fly after a shallow dive?

DCS risk varies as a smooth function with depth and time. There is not a bright line division between safe and unsafe, but rather just a gradual transition from safe to unsafe.

Using the various models, one could estimate a depth shallower than 20' that would have the same risk with an ascent to 8,000' (max airplane cabin altitude),as an ascent to sea level from a 20' dive.

Alternatively, once could find a depth deeper than 20' depth from which an ascent to sea level has the same risk as an ascent to 8,000' from 20' depth.

 

[Saturation]

To further support DepartureDiver and Charlie99s position, one can even get bent while flying without diving at all, albeit its rarer and its depends how high one is in an unpressurized aircraft.

At sea level, one has a stable amount of N2 absorbed, but if one were to decompress too quickly during flight, such as in a rapid ascent, there is a possibility of taking gas out of solution and into bubble form. This is a common complication in bailing out of a plane at altitude where the decompression is rapid and explosive.

What is clearly missing in this theory are the issues around nucleation or microbubbles. This is one of Dr. Deco's pet theories, I leave the rest to him to expound.

If we take nucleation into account we may detail a crucial variable in bubble formation than just total inert gas in tissues. Inert gas in tissues is a function of depth & time and is the only factor most folks consider when estimating FAD.