Diving and Flying

[Jimmenycricket]

Hi all,

I am very interested in becoming a pilot, but also like to scuba dive. As I get into more and more technical diving, I start to wonder what the medical effects of diving before flying are. Does anybody here have any idea? (To give a reference, commercial divers work at very extreme depths, usually 200+ ft.)

Thanks!
JC

[Straight Up Again]

As a scuba diver, I too am interested in this, though it is unlikely my diving and work would clash.

From what I remember from learning to dive, the main effect seems to be decompression sickness (DCS, aka ‘the bends’).

I think the theory is that you may ascend slowly or do decompression stops on your way up to the surface, and this will get rid of the majority of the dissolved nitrogen in the body tissues. If you then jump in an aircraft, and zoom up to an altitude (8000ft in pressurised cabin?), this may have the same effect as a rapid ascent in the water, and cause the remaining dissolved nitrogen to come out of solution, due to the further decrease in pressure, and result in decompression sickness. This problem would be made much worse if there was a sudden loss of pressure at altitude. If you were in an unpressurised aircraft, the effect would be dependant on altitude.

One of the websites listed below also talks about Arterial Gas Embolism, which is small ruptures/tears in the lungs due to air expansion as the pressure decreases while surfacing. For this to happen you would have to be breath holding, or not breathing regularly, both of which are a pretty big no-no while diving (as they keep telling you on the courses).

This link has some good info on the whole DCS thing, with some info on flying further down the page. Effects of dissolved Nitrogen (http://www.mtsinai.org/pulmonary/books/scuba/sectiong.htm)

These other links show the variety of times recommended by different organisations.
Scuba diving and flying (http://www.sabadeep.com/saba3.htm)
More scuba diving and flying (http://scuba.about.com/library/weekly/aa122297.htm)
Arterial gas embolism (http://www.discoveringhawaii.com/SF_Medicine/SCUBADiving/ScubaDivingFlying.html)

The above is based on my knowledge as an amateur diver, I am not in any way medically qualified, and don’t know if this will be different for technical diving (involving decompression stops).

If I have completely the wrong idea I would be very grateful if someone could put me right, before I kill myself.

[Intruder]

Significant increased chance of "aviator's bends" and other nasties if you dive shortly before flying. General rule of thumb for military flying was 24 hours between SCUBA (non-decompression dives) and flying.

In commercial airliners, where the cabin altitude is seldom above 8,000', there may be less of a risk. OTOH, if you're doing decompression dives, the risk increases significantly again.

[Bad medicine]

This is a very complex subject, and handled differently by various organisations. Diving before flying certainly does increase the risk of decompression illness. Most dive tables include information on flying after diving, and if you work for a commercial diving operation, there should be strict guidelines on delayy until flying. These depend on type of diving, duration of dive, planned cabin altitude of aircraft, etc.

An example of some of the restrictions used in organisations around the place are:

Air/Nitrox dives with no decompression required (most recreational diving actually comes under this category) - if the cabin of the aircraft is to be <8000ft then allow sufficient surface interval for the repetitive factor to reduce to 1.0 (minimum 9 hours), Aircrew minimum 12 hours. If the cabin alt is to be >8000' then the minimum surface time is 48 hours.

For air/Nitrox dives where decompression stops are necessary, then the minimum times are 24hr (<8000') and 48 hrs (>8000') respectively.

Hope this gives you some food for thought.

Cheers,

BM

[2close]

I'll ask a friend of mine who used to be a commercial diver and is now a PPL to take a look at this and see if he has any thoughts.

One thing I have been told though is that, whilst some divers say they would never fly for at least 12 hours after diving and not for 24 hours if deeper than 30 ft, they will happily jump in a 4x4 and trot off up into the hills to 6,000+ AMSL straight after diving.

Errr, surely this is going to have the same effect, albeit the ascent is going to be a lot slower?

[Daysleeper]

Just a few thoughts.

cabin of the aircraft is to be <8000ft

Dont forget if you are unfortunate enough to suffer a decompression of the aircraft the cabin alt could reach 40,000 feet. Best give it at least 48 hours.

The hill issue is a good one. On the west coast of scotland we always advised people to give it half a day and the road is only 1000 feet up.

Still both are excellent (though addicitve and expensive hobbies) I'm always a bit concerned about people who go , for example , to the red sea on a liveaboard, do a week of intense diving then fly home the next day. Even though they may have had the minimum time the cumulative effects must build up in their systems increasing their risk of getting "bent"

[air pig]

Diving and flying have always been a difficult subject. The rate of nitrigen diffusion varies with tissue within the body and with individuals.

I would suggest that you contact Dr Phil Bryson and his colleagues at the Diving Diseases Research Center on 00 44 1752 209 999 or DAN europe,who may be able to advise you. The last I heard that dive to fly time under PADI rules had increased to 24 hours from 12.

People have become "bent" just by traveling over high mountain passes following a dive.

Safe diving and flying.

Cheers.

Air pig. Thats how I got my name.:ok:

[Jimmenycricket]

Thanks for the info everybody.
JC

[411A]

'Round about 1983, an SV First Officer passed away shortly after completing a domestic flight, having dived approximately 18 hours before.
He was taken off the aircraft assisted my medics and transported straightaway to hospital, where he died shortly thereafter.
IIRC, the cause of death was acute decompression sickness, with 'complications', the nature of which I could never ascertain.
SV had a policy at that time that prohibited flight crew from flying for 48 hours after diving.

Clearly, flying and diving don't mix all that well.

[strake]

Slightly off-subject but perhaps relevant.

My club in Florida, which has a lot of out of town/country visiting divers, has been using Nitrox since 1997 (as have I). Since that time, there has been no occurence of any noticeable form of DCS with divers using Nitrox.
Out of interest, has anyone heard of a Nitrox diver becoming "bent" either flying or not?

[simfly]

I'm sure when I was studying HPL at ATPL level, there was a section on this so may be worth looking up if you can find the books....

[Bad medicine]

Strake,

There have been many cases of DCS from Nitrox diving, including a number of fatalaties. Nitrox is a generic term, and there are a number of commonly used mixes of the 2 gases. According to DAN statistics, there is very little difference between the incidences of DCS breathing air or Nitrox. Nitrox use can extend bottom times, but there is still a risk of DCS.

Hope this helps,

BM

[Rwy in Sight]

Jimmenycricket,

If I recall, my diving theory (taught 10 years ago today!) and if you dive under the British underwater regulations (bsac or something like that) there is a set of tables. We were taught to not to fly until we returned and remained to an A table for at least 24 hours - based on depth and time spent underwater.

Rwy in Sight

[Synthetic]

The problems are made worse if the aircraft were to suffer a decompression (especially an explosive one). Even with a very low nitrogen loading, the sudden change in ambient pressure could bring on an instantaneous occurence of the bends

[Jimmenycricket]

Thanks guys!
I know that my dive instructor suggested waiting 24 hours, but that was for non-decompression dives. As I get into the technical stuff, I have to decompress occasionally, and the effect might be worse. After those dives, would you think that 48 hours is enough?
Yes, diving is quite expensive, and quite addictive. I never thought that I would buy my own gear, I couldn't seem to justify it to myself. Eventually my parents told me if I didn't buy it now, I would never buy it. I find that it is a really relaxing activity, so I found the justification that I needed. But now it clashes with my other goal, to be a pilot. Why do things like this always seem to happen? Ah well, that's life....

[Ludwig]

Jimmenycricket, there are a couple of threads about this elsewhere, the last about mid July on Private Flying when Bose-X (a flying- diver) gave some scientific answers. I should think a search would bring something up. I'm sure he would reply himself, but he is I know,at this moment sitting on the sea bed somewhere!:cool:

[Quokka]

You can get dive computers that messure barometric pressure on land and adjust the calculations for removal of Nitrogen from the body accordingly. I always dive with a dive computer and I'd recommend anyone who was going for a drive up to the snow after a dive to take their dive computer with them. You could take it with you on board an aircraft... if you can get past the X-Ray machine Army...

[BIG MISTER]

I'd be very very very careful with this one and extend the suggested time by a fair margin !

Having been the one thats had to escort a number of poor souls from the Airport to a hospital that can treat them I can tell you the standard brief from the Ambulance guys if we dont have radio contact is.......if we turn off the lights then he did'nt make it ! ! !

:ugh:

[Synthetic]

Quokka

If your dive computer has been x-rayed, regard it as scrap. Especially as it is efectively a piece of life support equipment.

(X-rays are one of the ways of wipeing the memories used in these).

[gblen]

diving and flying dont mix, trust me. I failed my class 1 medical because I have dodgy ears brought on by diving. Burst an ear drum and did some inner ear damage about a year ago and just failed my class 1 two weeks ago. i had an ear infection that i didnt know about, no pain or anything, it weakened my ear drum and after 2 dives in a day, one deep and one to 15 metres, my ear drum packed it in with out warning as i landed on the bottom. end of flying career. i also have narrow eustacian tubes that connect the inner ear without the back of the trcoad so you can equalise the pressure, this caused a reverse block that caused my eardrum to pop inwards. failed the medical because if i burst it again while flying due to a sudden loss of cabin pressure, i would have no control over my balance for a bit and couldnt fly the plane. an airline wont hire someone thats a risk. mind your ears when diving, a visit to the ear nose throat doctor is worth it because i didnt know i had any problems with my ear until i went after I burst it diving. people are designed with bad ears and in that case, diving and flying ont mix

[Teddy Robinson]

The fastest growing recreational sport meets the most popular form of foriegn travel.

As others have said, this is potentially a very complex subject, and becoming more so as Trimix courses become available to the recreational diver.

I do both, at a professional level, although the diving is not as frequent as it used to be.

The CAA/JAA guidelines are that 12 hours should elapse between a shallow dive and flying, whilst the diving organisations (who are more likely to end up in court) say 24 hours.

After a solid two weeks of leading dives in the 12 - 40 metre depth band, plus an occasional forray past 50 metres with friends, my Aladin computer gave me a desat time of 32 hours, with a no fly limitation of 14 hours.

I use the desaturation time rounded up to the nearest 12 hours so in the case above 36 hours before my flight home I will have packed my kit.

You may use Air/Nitrox/Trimix, do deco/non deco dives, use tables or a computer, whatever, I would suggest that you work on the safe side of when your nitrogen loading is ZERO, and if you are serious about your diving then a good computer is invaluable.

As for X ray machines reducing dive computers to scrap ? thats a new one on me, my computer travels the world and shows no ill effects.

More to the point, if you are flying, it should mean that you are completely desaturated.

Ergo the information in the volatile memory is irrelevent.

[S-Works]

Diving and flying mix just fine if you understand the rules for both, several thousand hours under water and above have done no harm to me and both my HSE diving medical and Class 1 or in date. Some people are just predisposed to medical problems.

Regards, X-rays and computers- Tosh, X-rays do not effect dive computers.

Taking your computer on an aircraft to watch the display will do you no good either, they are not calibrated for surface use and the resolution for altitude equalisation is based on 300m increments and merely reduces the no stop time and then lengthens the deco time.

Regards flying and diving there is no definative answer for the no fly time and if you choose to ignore the various agencies extremely conservative guidelines then it is a personal choice.

Helium breathing mix dives are a safer bet to fly after than air. Helium is a thinner gas than air and enters and leaves the body rapidly. There is not enough ambient pressure to hold Helium in the body above about 3-6m so if you are going to get a bend you will get it in water on helium, for this reason stops are started deepr on Helium. As an example, from a 140m dive last week my first stop was at 118m. yes that meters not feet.

I regularily fly in the afternoon after diving in the morning and after 23yrs and more than 8,000 dives probably have enough of a statistical base to support the theory.

And for the record yes I did right the book! Anyone who wants to know the ins and outs of bubble seeding, doppler counts and decompression theory PM me and I will be happy to bore you to death.

At the end of the day my advice is if you do not have the understanding of what you have done to your body then follow your training agencies advice and use there guidlines for no fly.

[Jimmenycricket]

Thanks!

With regards to a dive computer, any suggestions as to which I should invest in? (Please bear in mind that I am still a student, and thus am working on a limited budget.) Although I have the greatest respect for PADI dive tables, a computer would make me feel even more comfortable.
Bose-x, did you say 140 meters? Praytell, what were you doing at that depth?

JC

[S-Works]

VR3 Dive computer is my weapon of choice.

Diving a frigate that was sunk during the Turkish occupation of Cyprus.

140m is an extreme dive but by no means my deepest, I held the world record once for a closed circuit dive at 205m.

PADI dive tables are very good safe and reliable tables don't underistimate them for no stop diving. A computer is a great tool just make sure you understand what it is telling you and why!

[Jimmenycricket]

Oh, don't worry, I understand what the tables are telling me, and how useful they are, but I would just want to be able to maximize the time I have for diving, since at this point it only happens occasionally.

[SR71]

Just as an illustration of what you can "get away with", back in 2000, I did 41 "air" dives in 10 days in Bonaire, with ~20 in excess of in 40m, a maximum depth in excess of 70m and maximum dive time of > 100mins.

I'm fascinated by the physiology of decompression but like bose-x suggests, it seems to be down to the individual more often than not and a sensible knowledge of your own limitations.

Often wondered whether the fact that I've been a body-builder in the past and continue to indulge this passion of mine actually predisposes me towards DCI or mitigates against it?

Enjoy.

:ok: