Hey everyone,

My girl and I are taking a scuba diving trip this summer, and we are thinking of buying some gear, otherwise renting. We already have all our own free diving gear, and we're looking forward to flying around the coastal backcountry diving secluded spots rich for spearfishing with friends and family. We dive a lot, just not with tanks.
Now if I were able to bring a small scuba diving tank into the backcountry regularly, it would be worth us owning our own.
So my questions are these:

Is the idea of transporting a heavy, pressurised vessel in a small GA aircraft (Bearhawk, fabric walled baggage compartment) just plain dumb?
Can you fly with dive tanks safely at low/medium altitude (sea level to say 7,000ft ASL max), or are the pressure changes at altitude just too dangerous to risk with a pressure vessel?
Are there rules or regulations I should be aware of?

In terms of flying and diving (nitrogen narcosis) I can figure all that out with the dive computer. It would only be a smaller tank for short dives and we'd only use it on longer trips, e.g. no flying the day before or afterwards. That is not the thrust of my question, I understand those risks.

Someone slap me if this is just a plain dumb idea.

Why not. Do you drive with them in your car? Here in the Western US folks drive over mtn passes all the time with scuba gear on board. And fly. They're not fragile, and not going to catch anything on fire if a valve opens when bumped.

Gump

The difference in pressure between sea level and 10,000 ft is only about 4-5 psi. Dive tanks are generally filled to 3,000 psi give or take. The altitude difference is barely a drop in the bucket for the limits of those tanks.

There was a time when I was really into both Free and SCUBA. Like Gump and Zzz said, transporting tanks in a plane is no different than in a car, just make sure those heavy bastards are secured and I'd probably place them sideways in the plane in the unlikely event of a botched landing with the point being if the valve ever sheared off, they'd depart the side of the plane and not through you.

With that said, you do have to be careful about the bends when flying after diving. As you probably know, the rule of thumb is to wait 24 hours before flying; however if you don't climb very high, I don't believe it matters. The 24-hour guidance is for people who make long deep dives, and an hour later get in an airliner that within a few minutes reaches a cabin pressure of about 8,000 feet. Even then chances are remote, but it is possible for someone to get bent. Just use common sense about it and you'll be fine. Nitrogen narcosis is real and can significantly impair judgement below about 80 feet of depth. The effects diminish rapidly above that so won't affect flying judgement.

You face much greater dangers in the water than you do in the air after diving. It is hard to find the statistics, but free diving is much more dangerous than we might imagine as a result of shallow water blackout. You are probably aware of SWB, but for those who are not, if you see "stars" after surfacing and who hasn't after a long breath-hold dive, common thought is that in those cases you are only seconds away from SWB due to a lack of O2; it is almost always fatal. Be careful out there.

Get a high pressure 80 tank,the physical
Size it that of a 65 but with 80cubes of air.
3000 psi. It weighs about 40 lb.
Depending where you dive(or plan to dive)
think about renting the tanks and weights.
We dive Tahoe a lot and transport the gear
as gump said.
Strap them down real good,have fun.
Chuck.

Lots of excellent advice has been posted. I would just give an extra bit of caution. In NOAA, we got paid to dive, in addition to our flying around. We would fly about from Marine Sanctuary to Marine Sanctuary and do dives to check on regular projects we had underwater. I have had two incidents with divers each time the group did exactly the same dive. We get off the boat go down to the frames, take the photos, come back together. Same bottom times, same dive profile. Two different people got bends symptoms, while the others in the group didn't.

So bottom line, be careful, what works fine with one person may not with another. We are just not all created equal and our uptake to nitrogen is slightly different from person to person. One of my NOAA buddies now runs a network of decon chambers on the east coast and Caribbean, makes a fortune off this. Enough for a home on the private island of Cat Cay. Another friend's wife has been bent twice, first on a flight and the second time after a regular dive. You actually become more susceptible if you've been bent once, why I have no idea.

As far a flying with the tanks. Yes, really secure them well. When I was HS & college I worked at Laguna Seasports, a local dive shop. On a Sunday morning I got to watch a tank rocket across the Coast Highway when a butterfingered dufus dropped a tank on its valve. It kind of made the girls working at Dukes Burger across the street drop their load as it zipped through the parking lot at high speed making enough noise to wake the dead.

If you really think about it, many aircraft have large pressurized tanks in them containing O2. The Caravan has a 112 CuFt Kevlar O2 tank, the Chieftain has a 32 CuFt steelie and the 185 also has a 32 CuFt tank option as well. Get some of the U shaped plastic floor holders that keep them from rolling in the back of your car. Then strap them down.

Routine in my Beaver days to throw a few tanks into the Wipline float compartments for the logger/divers in some of the coast camps. Back haul the empties, usually with a reward of abalone, rock scallops, crab, etc.
Even used a tank myself once to retrieve a nice pair of Serengeti sunglasses that fell out of my shirt pocket when I was tying up at a dock. 30', no fear of bends at my altitudes.

Thread creeeeep. Beaver comment reminds me of the docks in Alaska. If you dove beneath any seaplane dock you would find a treasure trove of junk dropped. Glasses, cameras (not so good) Bikes, Wallets, various freight.
Anyway, good advice here about strapping the tanks. Have FUN.

About 5 years ago, some divers helped with the recovery of a Helio floatplane that had crashed & sunk in Lake Isabella in the Cascades west of Seattle near Monroe WA. The surface elevation is close to 3,000 feet, and the lake is pretty deep, so I guess there was some complications: special gasses used, wait time between diving and flying, etc. Some of the dive people involved posted on the internet about it, you can google it up if interested.

Like others have said I don't think the tanks are a problem in your plane. I tried to rent some tanks in Hawaii and they wouldn't let me go because it hadn't been long enough since I was flying. I had been on a tour and I doubt we were over 1000'. I would look into it because out in the mountains your on your own most of the time. Good Luck!

Thanks for all the advice guys - sounds like it is less of an issue than I thought.
We better go look at some BCDs and tanks when the Boxing Day sales start. Shame about the weight of tanks + weight belt.

Thanks Mike for the warnings about SWB, we are familiar with that risk and are always careful. I use a dive computer (/watch) which has a 'FREE' mode that tracks surface time, bottom time, depth, number of dives, etc. Cressi EDY. We work by up-time doubles your bottom-time and never really push much beyond 1:30 underwater. That is usually more than enough to see the fish you're after anyway.

Did anybody mention that lots of little airplanes, even mine, have oxygen tanks which are virtually identical to scuba tanks except painted green and filled with oxygen to around 2000psi instead of air?

S7Paco wrote:Did anybody mention that lots of little airplanes, even mine, have oxygen tanks which are virtually identical to scuba tanks except painted green and filled with oxygen to around 2000psi instead of air?

Who are you, Steve Zissou?