No Fly Time Calculation No computer

[talonraid]

Another vote for 24 hours.

Also, like mattboy said, consider that commercial aircraft are: 1) pressurized for comfort only, so it's not like sitting at sea level 2) although unlikely you really get decompressed in the event the aircraft has a rapid decompression.

 

[DandyDon]

Where did all this come from?! We encourage safe diving on this board, but the trend here looks pretty extreme.

http://www.diversalertnetwork.org/medical/faq/faq.asp?faqid=54

Yeah, I'd say that DAN knows more about all this than all of us here combined, that they're quite conservative, and don't they suggest 12 hours after a simple, single dive or 18 after multiple dives or diving days - for a diver show no DCS symptoms? I sit 24 hours after a Decom dive, but those are rare for me.

It's common for computers to have a 24 hour countdown to fly, but I really suspect that was left on there after DAN updates a few years ago because of lawyers.

 

[miketsp]

Where did all this come from?! We encourage safe diving on this board, but the trend here looks pretty extreme.


Yeah, I'd say that DAN knows more about all this than all of us here combined, that they're quite conservative, and don't they suggest 12 hours after a simple, single dive or 18 after multiple dives or diving days - for a diver show no DCS symptoms? I sit 24 hours after a Decom dive, but those are rare for me.

It's common for computers to have a 24 hour countdown to fly, but I really suspect that was left on there after DAN updates a few years ago because of lawyers.

I don't see any inconsistency. In the FAQ DAN suggests a minimum of 18hours.
They also state:
The recommended preflight surface intervals do not guarantee avoidance of DCS. Longer surface intervals will reduce DCS risk further.
So rounding up to 24 hours can only be beneficial. Since my post-dive flights tend to be long, at least 4 hours and quite possibly 10-12, the last thing I want is a hit at 30000ft.

I also found it a little strange that the FAC dates from the 2002 consensus.
I was sure I had read un updated study in DAN's Divealert mag within the last 2 years and that the trend was to put an additional safety factor on the 2002 limits. I need to dig into my pile of mags at home to check.

Of course if you really need to push the no-fly limits then make sure your ascent profiles on the last day are smooth & slow. Add an extra stop at 10m and stretch out the 5m safety stop by an extra few minutes. Get as much gas out of your body as you can.

 

[sasscuba]

24 hours.

 

[bperrybap]

Just my opinion. Simple rule for commercial pressurised aircraft.
Single days diving (2 dives) with safety stops, no rapid ascents and no deco, 12 hours.
Multiple days diving or any deco dive, 24 hours.

If flying a non-pressurised aircraft above 3000ft (there are still some around in more remote spots) I'd add another 6-12 hours to each of these times.

Huh?
You must mean above 8000 ft because comercial air craft are
only pressurized to 7-8000 ft. So flying on a comercial jet
is the equivalent of flying in an open cockpit plane to 8000 ft.

--- bill

 

[DandyDon]

Well, 24 hours is at least 18, yep.

I like planning conservative dives for the last day, but diving. Do the deep stops on any deep dives, long safety stops, hidden stop on surface for every dive. If there is a good dive available between 18 and 24 hours out, I'll do it.

Huh?
You must mean above 8000 ft because comercial air craft are
only pressurized to 7-8000 ft. So flying on a comercial jet
is the equivalent of flying in an open cockpit plane to 8000 ft.

--- bill

Yes, Don't you pop your ears on take-offs and landings? The pressure in the cabin may not be that low, but lower - and may be that low on occasion, so we plan on that. ilot:

 

[bperrybap]

I guess what I was trying to say but didn't say very well, is
that when you travel on a commercial jet, the cabin is only
pressurized to an altitude of around 7000 to 8000 ft NOT sealeavel.
(I've actually measured around 7800 ft multiple times with an
altimeter)

The comment about flying in a non pressurized air craft
above 3000 ft makes no sense to me since you are exposed
to higher altitudes (lower barometric pressure) by
simply traveling on a normal commercial jet aircraft.

So if you were trying to really ride the edge, you would need
to add more time for the pressurized flight than the non
pressurized flight. At least until the altitude of the non pressurized
flight exceeds 8000 ft.


--- bill

 

[Damselfish]

I at least follow my computer which usually wants something around 18-20 by the time I'm done diving, but I try for 24. If it's 23 I'm not going to get my wetsuit in a knot.

 

[miketsp]

Huh?
You must mean above 8000 ft because comercial air craft are
only pressurized to 7-8000 ft. So flying on a comercial jet
is the equivalent of flying in an open cockpit plane to 8000 ft.

--- bill

Quite right, early morning mental glitch. I was thinking 8000 and typed 3000 and on the small screen laptop I was using the 3 and the 8 are very similar so I didn't spot it. On the 17" monitor I'm using now it's quite obvious.

 

[texdiveguy]

24 hours.