Suunto No Fly Time

[StingRob]

Here a link where Dan explains how flying after diving is determined, what type of experiments are conducted... also a note:
"Note that we cannot actually measure probability - we can only estimate it statistically from experimental data..."

http://www.diversalertnetwork.org/medical/articles/article.asp?articleid=20

Robert

 

[DavidScubadiver]

"While in the air I was looking at the computer and the nitrogen load went way up for most of the flight since cabin pressure is around 7500 ft. "

Page 94 of the D9 Manual states as caution:

• Do not test or use the dive computer in pressurized air.

A "Caution" means that the activity could result in damaging the device. I guess that means the watch should not be in dive mode when you fly...
​

 

[Charlie99]

age 94 of the D9 Manual states as caution:

• Do not test or use the dive computer in pressurized air.

A "Caution" means that the activity could result in damaging the device. I guess that means the watch should not be in dive mode when you fly...
​

I think you are misinterpreting the caution.

It is easier to make a seal that keeps out water than one that prevents any air from entering.

I read the caution as telling you not to put the computer into a pressure pot tester and take it down to, say 100'/3atm/4ata while leaving it in air, rather than having it in a little tub of water inside the pressure pot. If I understand it correctly, you are less likely to get water trapped inside the computer than air.

OTOH, whether or not you turn on the computer while flying, it sees the same pressure differentials --- the difference in pressure between sea level and maximum cabin altitude is about 1/4 ata or 8fsw.

Charlie Allen

 

[Charlie99]

While in the air I was looking at the computer and the nitrogen load went way up for most of the flight since cabin pressure is around 7500 ft.

What you saw on the computer wasn't that your N2 loading went up, but that the allowable N2 loading limits are decreased with increasing altitude. The computer displays N2 loading as a fraction of the allowable limit, so the reduced limit at altitude causes the bargraph reading to increase immediately as you ascend, while your N2 loading only slowly decreases over several hours.

It's kind of the reverse of a 10' deco stop, where the allowable N2 loads are increased because of the additional 10fsw of pressure, and you can ascend to 10' with N2 loads that would bend you on the surface.

One way of looking at the pre-flight no fly time is that it is an extended deco stop at sea level that allows you to offgas enough that you can now ascend a bit further.

 

[red_barbarian]

I think Charlie99 is correct. I know several people in Co that specifically bought their Duo's for altitude diving, myself included. As for the Mosquito being conservative, I use it as my backup computer. It is consistently less conservative than the Duo, both in no-fly time limits and in the water w/ NDL remaining.

 

[WarrenZ]

I would listen to the computer it is better to err on the side of caution then to have a problem. I allways allow myself to decompress for 24 hours before flying everytime.

 

[tboxcar]

It's not surprising to hear about the long 'NO FLY TIME' , in June while on a liveaboad in the Philippines we were doing 5 dives a day and ended up doing 20 dives in a 4 day period. At one point it read over 29 hours until I could safely fly again. It was fine with me as I had no plans to fly, but we had a few laughs about it!

 

[Matt S.]

My D6 showed a no-fly time of 44 hours after one evening of PADI OW pool sessions. During this time it recorded 6 "dives" of no more than 8 ft, and at most something like 8 minutes.

Pretty conservative!

 

[RV]

My Vytec will give a 24hr no-fly after any real dive below 4 feet.