Private pilot - flying after diving

[Atticus]

I know the FAD issue has been beat to death, but I have a variant on it that I'm seriously looking for information on.

I do deco diving, and I'm a private pilot (generally unpressurized singles).

I'm concerned that the standard 12 hr / 24 hr rule is for flying commercial, and as a passenger. Flying myself I have to contend with higher altitudes (I live on the other side of the Sierras from the Pacific Coast, and will generally fly back at 11,500 ft). I also am the pilot, so any problem is much more serious than if I were just a passenger.

Clearly having oxygen available in the plane is a benefit, but I'm concerned that in nearly any DCS incident my chances of successfully landing are marginal.

Are there any recommendations for this? My personal rule has been 72 hrs, but this makes quick vacations pretty rough, and seems like it might (?) be overly conservative.

Thanks in advance,
Atticus

 

[Charlie99]

NOAA fly after dive tables have entries for up to 10,000' altitude, so that gives you a bit more guidance on what could be safe.

The real problem of fly after dive is that not all offgassing is reciprocal. Once bubbles, even small ones that don't cause obvious symptoms, have formed in your tissue, they will not come out at the same rate that the N2 dissolved into your tissues.

 

[BigJetDriver]

Atticus once bubbled...
I do deco diving, and I'm a private pilot (generally unpressurized singles).

I'm concerned that the standard 12 hr / 24 hr rule is for flying commercial, and as a passenger. Flying myself I have to contend with higher altitudes (I live on the other side of the Sierras from the Pacific Coast, and will generally fly back at 11,500 ft). I also am the pilot, so any problem is much more serious than if I were just a passenger.

Clearly having oxygen available in the plane is a benefit, but I'm concerned that in nearly any DCS incident my chances of successfully landing are marginal.

Are there any recommendations for this? My personal rule has been 72 hrs, but this makes quick vacations pretty rough, and seems like it might (?) be overly conservative.

Thanks in advance,
Atticus

Atticus,

You are right to be concerned about the way your particular activities affect your personal situation. As our good Doc. Deco has pointed out, the tables we use are only valid FOR THE STATED TEST CONDITIONS. As soon as we start departing from those conditions the reliability of the results has progressively less and less application to our present state.

You are right to be cautious. As Charlie99 has pointed out, the on-gassing and off-gassing rates, based on current research, are NOT symmetrical.

The table he refers to can be found on page 4-28 of the NOAA DIVING MANUAL, Fourth Edition, Best Publishing. As an example, starting at Repetitive Group Designator "I", the wait time is 24:00 before going to 10,000 feet pressure altitude. The wait time for "Exceptional Exposure" is 48:00. (Note: The NOMINAL cabin pressure assumed for commercial flights is 8,000 feet.)

As someone who has been a professional pilot all of my adult life, I applaud you for your VERY professional, and conservative attitude!

 

[Atticus]

Thanks for the responses. I understand that pretty much all the decompression data we have is from running experiments and then extrapulating from them - ie: unless there are a bunch of pilots out there that would like to test deco diving followed by flying we can only infer from 'similar' experiments.

I'll keep to my 72 hr rule and err on the side of caution.

Best Regards,
Atticus

 

[Dr Deco]

Dear Atticus:

I might guess that 48 hours would be sufficient, but that is only a guess. I do not have any data on this question.

Dr Deco :doctor:

Readers, please note the next class in Decompression Physiology :grad:
http://wrigley.usc.edu/hyperbaric/advdeco.htm

 

[djkeeler98]

Atticus once bubbled...

Are there any recommendations for this? My personal rule has been 72 hrs, but this makes quick vacations pretty rough, and seems like it might (?) be overly conservative.

Thanks in advance,
Atticus [/B]

Atticus-

The rule for U.S. Navy pilots is 24 hours. 12 hours with a flight surgeon's approval. I'm not sure if the FAA has any guidlines - might want to check the FAR/AIM.

72 might be a little conservative but it's really your call.

 

[BigJetDriver]

Well, we now have an actual case of a diver who, by his own testimony, cut short his time between diving and flying, and got bent as a result. We can read his story in Basic Scuba Discussions in the thread entitled: "I just got bent!" Makes for very sober reading!:doctor: