taking unpressurized flights after diving

[Gene_Hobbs]

This is Dr. Deco's area so he would know MUCH better than I.

So looking harder I did find this one by Dr. Deco that was added to the Repository on 2006-08-21T03:27:28Z. Hope this is more like what you were looking for...

DECOMPRESSION LIMITS IN COMMERCIAL AIRCRAFT CABINS WITH FORCED DESCENT.
Powell, MR 2002 UHMS Abstract
RRR ID: 1181

 

[Thalassamania]

My whole life I've used two approaches to flying after diving:

1. the "Group C" guideline (well the old Navy guideline was Group D, but while a "D Diver" just over the line from "C" is fine to go to 8,000 ft, a "D Diver" just about to go to "E" is not).
2. the fact that 2 hrs of 100% surface oxygen will take a 'Group N" diver to "Group A."

There are ways to go from a dive computer to a set of Navy tables for a group, see Mike Emmerman's paper in the AAUS Diving Computer Workshop.

 

[lizardqueen]

since it looks like the Wizard's hand-held altimeter idea would give me the info I need, I'm going to try carrying the radio I use when I go skiing - it has an altimeter feature where you calibrate it at a known altitude, and it tracks you from there. not sure if it'd work on a pressurized flight though.

 

[Flightlead]

since it looks like the Wizard's hand-held altimeter idea would give me the info I need, I'm going to try carrying the radio I use when I go skiing - it has an altimeter feature where you calibrate it at a known altitude, and it tracks you from there. not sure if it'd work on a pressurized flight though.

assuming it works on ambient atmospheric pressure and is not a ground proximity radar it should work fine.

 

[Flightlead]

We tried to summarize the available literature here. The tables on our page are fuzzy so please download the actual PDF of the referenced chapter in the US Navy Manual.

NOTE: This is by NO MEANS an exhaustive list. This is just some of the resources available online.

Bottom line is that it all comes down to your own concept of acceptable risk.

This is great stuff. I'm currently toying with the idea of buying a small airplane so I can zip back and forth between Atlanta and Florida to make trips to the springs etc a bit more feasible. If my home airport is around 1,000' MSL and I enter the pattern 1,000' above that, frankly, that would make 2,000' MSL my max altitude for the flight (heh heh in between I scare the sheep). Assuming I'm departing from near sea level then according to this: (ok, I've tried to format this table twice and it just isn't working)

Maximum Altitude Minimum Delay Minimum Delay
After Diving Single, Low Stress Dive Multiple or Deco Dives
1000 Ft. (300 m.) none none (low stress)
6 hrs. (mod stress)

2000 Ft. (600 m.) none 2 hrs. (low stress)
8 hrs. (mod stress)

4000 Ft. (1200 m.) 8 hrs. 12 hrs.

6000 Ft. (1800 m.) 12 hrs. (F.A.D.) 24 hrs. (F.A.D.)

I would only have to wait 2 hours after a day of typical springs or PCB/Destin shore or boat dives. There's no possible way I could even pack up, get back to the plane, kick the tyres, light the fires, and taxi to the nearest runway in that amount of time.

Am I reading that right? is this data accurate?

 

[Thalassamania]

If you want a little extra margin, slap on the oxygen.

 

[Flightlead]

If you want a little extra margin, slap on the oxygen.

great for a hangover too! (curing one that is, I find red wine good for the other)

 

[divebri]

While all the data is fine, get more basic:
I'm a commercial, single and multi-engine instrument pilot, with hours in everything from Cessnas to King Airs.
You would be PIC in that plane, correct? And you're assuming a max altitude that does not account for any flight restrictions, any chance you may have to climb for weather (or ATC, but if you're VFR there's not much chance of that), or having to re-route over higher terrain.

If by some chance you have to climg higher, and get bent, the possibility exists that you could be mildly to completely incapacitated. Then what?

Also, I don't know how much time you've got, but you aren't allowed to carry compressed gas even in a private airplane, so you can't bring tanks. And PLEASE PLEASE PLEASE check your weight/balance for the plane you're flying. If you don't have accurate weight info in that plane, GET IT. And then do the w/b if you remember, or have a CFI help you. You will carry a crapload of weight and if two people are going diving in a plane with a 900 lb payload, well, you're gonna be very close.

I had a 414, which is pressurized, and I could go from Phoenix to CA low enough (even IFR) to keep the cabin altitude at sea level. I would never take the chance that I wouldn't have to climb for traffic or weather, and that the pressurization system wouldn't fail at the worst possible time.
General Aviation and scuba don't mix except over time. If you really gotta dive, you really need to drive.

 

[Flightlead]

I'm a commercial, single and multi-engine instrument pilot, with hours in everything from Cessnas to King Airs.

me too, cubs to hawker jets

You would be PIC in that plane, correct?

yep

And you're assuming a max altitude that does not account for any flight restrictions, any chance you may have to climb for weather (or ATC, but if you're VFR there's not much chance of that), or having to re-route over higher terrain.

I'm assuming a vfr flight over, essentially, nothing but grass, trees, and livestock. ESA for an IFR flight on that route is a bit higher I think, I'd have to look at the chart but I'm guessing its probably 3-4k and thats in the approach environment. anyway, I'm probably not looking at an IFR platform.

If by some chance you have to climg higher, and get bent, the possibility exists that you could be mildly to completely incapacitated. Then what?

it is perfectly acceptable, and quite legal, to refuse a reroute. its done all the time based on fuel requirements, sickness on board, aversion to going "feet wet" etc. if I can't read a weather chart I've no business flying. if I plan a flight into a thunderstorm I've no business flying....and probably won't be not after penetrating the cell. heck, I once heard a Lear captain refuse a hold because he "hadn't flown a holding pattern in 20 years". 'course his option was to throttle back and fly to Scranton and back. ultimately it boils down to, if the parameters of the flight don't match what I can do (IFR, altitude, etc) then I don't go. too many friends at the bottom of smoking holes in corn fields to make that mistake :-(

Also, I don't know how much time you've got

several thousand hours

but you aren't allowed to carry compressed gas even in a private airplane

not true. I carry O2 all the time when cruising at high altitudes. in fact its required above 15k and any time in excess of 30 minutes over 12.5k in unpressurized aircraft.

You will carry a crapload of weight and if two people are going diving in a plane with a 900 lb payload, well, you're gonna be very close.

200lbs (me) 115lbs (wife - daughter is half that), 2 full tanks (80lbs or less), bcs, wetsuits, towels, lunch, 25lbs. 420. gas for 242nm at 6.5 gph at 120 kts plus 45 min reserve roughly 110 lbs. total 530 lbs. easy no prob even in a 2 seater.

General Aviation and scuba don't mix except over time. If you really gotta dive, you really need to drive.

yeah, that's what the FAA said about drinking, but America West still hired me

 

[divebri]

low-dive pilots/divers, and they always worry me. Obviously, you know what you're doing both in diving and in flying, and if you're flying Hawkers you know how to do a w/b. My apologies.
I understand you can always refuse a re-route, especially VFR, but you sure as heck don't give yourself much of a safety margin if you're bumping up against some altitude limit and need to go higher to any reason.
Correct on the O2 (even presurized a/c have O2 bottlles for in-flight requirements) but you can't carry compressed gas, flammable liquids or firearms ammunition on board as cargo or luggage. Am I correct on that?

As I said, I've seen some posts about flying/diving from people who knew very little about either. My first a/c, a Mooney, is in 800FSW in the Sea of Cortez because "the engine quit" while they were trying to get through/around a storm.
Yeah, they always quit, WHEN THEY RUN OUT OF GAS.
Out here in AZ, getting in to the coast is always a guessing game VFR. Getting out, too. I'v'e never been there when I didn't need an IFR plan to get out or in.
I don't know what it's like on your coast, but I imagine you might have the same issues. Only difference is we're having to hop over much higher terrain to get anywhere. MEA's for IFR flight are almost always in the teens.
Good luck in your search - I would have loved to use my plane to save time, but it just didn't work for me as far as diving went.