Fying/driving after altitude diving

[boulderjohn]

I would like to read a good and thorough discussion/explanation of flying and/or driving after an altitude dive. We had a brief discussion on this in the Rocky Mountain Oyster club, but I wanted to throw this out to a wider audience.

Some things to consider in this discussion:

1. If someone dives at 7,000 feet, how does that affect a decision to fly in an airplane pressurized to 7,000-8,000 feet? (I have heard both figures, with the 7,000 foot figure coming from a pilot/air traffic controller.)

2. If someone dives in Utah at, say, 5,000 feet, what consideration should there be before driving to Denver through the Eisenhower tunnel (11,000 feet).

3. In a drive described in #2, the diver would have a gradual increase in altitude, thus increasing the pressure gradient slowly. How would that affect the off-gassing rate?

4. How about a smaller increase in altitude, say going from the Blue Hole in New Mexico (4,600 feet) to Raton Pass (7,800 feet)?

 

[Leslye]

Littleton here...don't know how in the heck to use this site (and too lazy to figure it out) but if anyone is reading...anyone in the Denver area looking for a experienced dive partner to go on dive vacations with? White single female (old, 50, but fun) looking! Male or female apply!

 

[TheAvatar]

10 minutes from the tunnel here.

What you need are the NOAA ascent to altitude tables. These will tell you how long you must wait before ascending various amounts. Remember, you can count the time it takes you to get to Eisenhower as delay time in the table but remember you will reach higher altitudes than your start before you get to Eisenhower.

As far as the flying after a dive at 8000ft, if you are flying in a pressurized aircraft you aren't in any danger from a *normal* flight because the cabin altitude *shouldn't* exceed 8000ft. HOWEVER, if the aircraft suffers a pressurization failure... that is why you wait 24hrs before flying.

IF YOU ARE ASCENDING TO DIVE AT ALTITUDE DON'T FORGET THE FIRST TABLE IN THE SET AS YOU COULD ALREADY HAVE AN EFFECTIVE NITROGEN LOAD!

I reccomend taking a class on altitude diving.

 

[saildiver]

10 minutes from the tunnel here.

What you need are the NOAA ascent to altitude tables. These will tell you how long you must wait before ascending various amounts. Remember, you can count the time it takes you to get to Eisenhower as delay time in the table but remember you will reach higher altitudes than your start before you get to Eisenhower.

As far as the flying after a dive at 8000ft, if you are flying in a pressurized aircraft you aren't in any danger from a *normal* flight because the cabin altitude *shouldn't* exceed 8000ft. HOWEVER, if the aircraft suffers a pressurization failure... that is why you wait 24hrs before flying.

IF YOU ARE ASCENDING TO DIVE AT ALTITUDE DON'T FORGET THE FIRST TABLE IN THE SET AS YOU COULD ALREADY HAVE AN EFFECTIVE NITROGEN LOAD!

I reccomend taking a class on altitude diving.

Be extremely careful in any increase in altitude after diving-I knew of someone who got bent after diving for several days after climbing a hill about 450 feet in elevation-dont "fly" in any way for 24 hours to be safe....Peace...Saildiver

 

[jagfish]

Be extremely careful in any increase in altitude after diving-I knew of someone who got bent after diving for several days after climbing a hill about 450 feet in elevation-dont "fly" in any way for 24 hours to be safe....Peace...Saildiver

Hard to say whether this was due to the heavy exertion (climbing) or the minor change in altitude...My vote would be for the exertion...

 

[TheAvatar]

I would say that is exertion as well, there may have been other factors as well. If that bent him, the altitude certainly was not good.

You can do everything right and still get bent. It's all about reasonable statistics. There is *always* risk.

The NOAA charts are very good. They work on a weekly basis.

 

[mempilot]

dont "fly" in any way for 24 hours to be safe....Peace...Saildiver

I fly for a living and dive a mix of rec and tec on my days off. I use the NOAA's ascent to altitude table(based on ending PG) rather than the arbitrary 12/24 hour rule. I've been using the table for two years now and have not experienced any problems. It's a risk I assume, but since this table was created by actual research and not by rule of thumb, I accept it with caution. Some dive/deco profiles allow me to be back in the air pressurized to 8,000 ft well within the 24 hours you mention.

Side note: I've tested this table on myself over more than one hundred dive/fly transitions. I've gradually tightened the margins over time. Remember, not all people will be inflicted with DCS/DCI within the same conditions, so what works for me might not work for others. Our pressurization systems max at 8,000 ft cabin altitude at max operating altitude. If an aircraft has a sudden and rapid decompression at max operating altitude, it won't matter whether or not you were diving or not. You will experience baratrauma and decompression symptoms in a most severe nature anyway.

I hesitate to post this, but since the table is available, I thought I'd throw it out there.

 

[triton94949]

10 minutes from the tunnel here.

What you need are the NOAA ascent to altitude tables. These will tell you how long you must wait before ascending various amounts. Remember, you can count the time it takes you to get to Eisenhower as delay time in the table but remember you will reach higher altitudes than your start before you get to Eisenhower.

As far as the flying after a dive at 8000ft, if you are flying in a pressurized aircraft you aren't in any danger from a *normal* flight because the cabin altitude *shouldn't* exceed 8000ft. HOWEVER, if the aircraft suffers a pressurization failure... that is why you wait 24hrs before flying.

IF YOU ARE ASCENDING TO DIVE AT ALTITUDE DON'T FORGET THE FIRST TABLE IN THE SET AS YOU COULD ALREADY HAVE AN EFFECTIVE NITROGEN LOAD!

I reccomend taking a class on altitude diving.

Exactly. You can find the information in The NOAA Diving Manual. You can order a copy from Best Publishers Inc.

Here is what my Google search came up with for you:

http://www.ntis.gov/products/bestsellers/noaadive.asp?loc=4-2-0

 

[HammerNoMore]

1. If someone dives at 7,000 feet, how does that affect a decision to fly in an airplane pressurized to 7,000-8,000 feet? (I have heard both figures, with the 7,000 foot figure coming from a pilot/air traffic controller.)

Actually this topic has been discussed at length, but I will try to answer as best I can. The topic of "short hops" comes up fairly often. The general consensus is that you a) cannot guarantee that a plane will stay at a certain altitude, weather or other factors may intrude and b) being in a pressurised aircraft is never a guarantee.

Now, my personal take. You are sitting at 7k feet, and ok. You get on an aircraft, that would only exeeed that by 1k feet if an in air emergency occured. Is a sudden 1k decompression worth risking? IMHO, no. Why take a chance? I plan my dives so that there is at least 12 hours between the last dive and the flight. Your opinion may differ, and if it does, I'm ok with that. Your safety is your concern. I have a young child and my life is more important than it would be I were single. POINT: You make up your mind what that slight chance is worth. Fact is that many DCS hits do not present until on an airplane.

2. If someone dives in Utah at, say, 5,000 feet, what consideration should there be before driving to Denver through the Eisenhower tunnel (11,000 feet).

I've done this. Not in Denver and the tunnel (I prefer Loveland pass myself). But in HI. Again, personally I feel that if I'm driving I'm ascending slow enough that I can recognise an issue. More importantly, I can immediatly reverse the effect by turing the car around. Somthing I cannot do on a plane.

3. In a drive described in #2, the diver would have a gradual increase in altitude, thus increasing the pressure gradient slowly. How would that affect the off-gassing rate?

Not much at all. Remember, that the weight of air is minor. The only reason airplanes cause problems is because they go up really fast. You would offgas more from that long drive from Denver to the mountains than from that drive up...

4. How about a smaller increase in altitude, say going from the Blue Hole in New Mexico (4,600 feet) to Raton Pass (7,800 feet)?

How about the ulta-marathon that goes from the Dead Sea to altitude... If it's slow enough, it doesn't matter...

James

 

[triton94949]

Littleton here...don't know how in the heck to use this site (and too lazy to figure it out) but if anyone is reading...anyone in the Denver area looking for a experienced dive partner to go on dive vacations with? White single female (old, 50, but fun) looking! Male or female apply!

You want the Rocky Mtn group:

http://www.scubaboard.com/forumdisplay.php?f=400

(I P/M-ed him/her as well).