drive to 5000ft. after diving.

[Spoon]

guys after diving i usually stay at our cabin at roughly 600m or 5000ish ft altitude. would this pose a problem? i do this 80% of the time and never had any problems yet i know people who have gotten the bends from doing this. where excatly do you draw the line on safe no altitude driving?

 

[Kim]

guys after diving i usually stay at our cabin at roughly 600m or 5000ish ft altitude.

There's something wrong here! Did you mean 1600m?

 

[Spoon]

Ther's something wrong here! Did you mean 1600m?

nope 600m, the top of the peak where i drive to by taal volcano is around 5500-5800feet.

 

[Kim]

Well...600 meters is close to 2000ft, so I presume you are driving over a high pass or something? In any event there was a fairly large discussion about this recently:
http://www.scubaboard.com/showthread.php?t=114230&page=1&pp=10

 

[MikeFerrara]

Kim, wile it was a long thread it wasn't a very good one.

Spoon, The issue with ascending to altitude after diving is that pressure continues to reduce. In Haldanian terms, the question becomes, at which point does the leading compartment reach it's critical tension. In other words if you dived to the NDL, the leading compartment is at it's M value (critical tension) but the table still clears you to ascend to the surface...but no further. If I remember correctly, "Technical Diving in Depth" has a good section on this which I quoted in a thread some time ago. The problem is that I don't remember if that thread was here or on another board. I don't remember what the NOAA manual as to say and unfortunately I need to head off to work so I don't have time to look it up for you. If I recall there are some tables for this using pressure groups. If so, remember that pressure groups from one table don't apply to those of another. Getting through the math isn't so hard but it's not something that I've had to apply to actual diving since we don't even have any good sized hills. My gut feel is that 5000 ft isn't too big a deal but if I were you I'd look this up and think through it.

 

[HowardE]

So far... the only problem I see here is the math

600 meters = 1968 feet

I thought that if you did ascend to 5000' that would be considered the same as flying?

 

[MSilvia]

I don't remember what the NOAA manual as to say and unfortunately I need to head off to work so I don't have time to look it up for you. If I recall there are some tables for this using pressure groups. If so, remember that pressure groups from one table don't apply to those of another.

According to NOAA table 4.3, a diver using US Navy tables (1999) on air can immediately ascend to 5000 ft. safely so long as he has not been in a repetitive group higher than "E" in the last 24 hours. He can goto 2000 ft. (much closer to 600m) so long as he hasn't been in group "H" in the last 24 hours. You may want to look into it in more detail though... If you've been in group "O" for example, they recommend waiting 9:24 before ascending to 2000 ft.

 

[MSilvia]

I thought that if you did ascend to 5000' that would be considered the same as flying?

Flying is calculated using 8000' as the cabin pressure, so it's a little different.

 

[angryguy777]

I thought airlines were pressurized to 6000 ft? I may be wrong, but I was told this went I went into an altitude chamber once.

 

[HowardE]

There was recently a discussion about this... Basically, it varies depending on the plane.

http://www.scubaboard.com/showthread.php?t=115335&highlight=cabin+pressure