28 Hours of No Fly Time?

[Neilwood]

Personally I would have no hesitation about flying after a 24 hr break after doing multiple non deco dives on consecutive days. That is based on DAN recommendations and the Alert Diver review - link

The review basically shows that, even with divers that are known to be susceptible to bubbling, that the level of bubbling at 24hrs is relatively insignificant and at a level which is "considered reasonably conservative and safe".

By all means though follow the computer if you wish as it is even more conservative than the DAN guidelines of 24hrs (which they consider conservative). Extra conservatism never hurt anyone.

 

[Graeme Fraser]

I contacted Leisure Pro about that article, and they are going to change or delete the article. They agree there is no support for the Navy saying 2h is sufficient before flying.

US Navy Diving Manual Table 9.6 (Required Surface Interval Before Ascent to Altitude After Diving) clarifies the USN position. They provide a sliding interval scale depending on Repetitive Group Designator and Achieved Altitude.

Worth noting that even USN state a mandatory 48hr surface interval for any Exceptional Exposure.

Anyone thinking of adopting sections that suit their purpose need to consider who these tables are primarily designed for (i.e military and commercial operations). You definitely can't 'cherry pick'.

 

[seeker242]

and his computer surprisingly says he should wait 28 hours, that’s not of interest?

Not really of much interest because Suunto is known to use it's own propitiatory algorithm, which is also known to be extraordinarily conservative. That alone explains the additional 4 hrs past 24. Hard to argue that it would be unsafe when tons of other computers would say 24 for the same thing.

 

[scubadada]

Can you name another?

Dive Rite Nitek Q

 

[tursiops]

They provide a sliding interval scale depending on Repetitive Group Designator and Achieved Altitude.

They also say to use 8000 ft altitude if you are flying in a commercial aircraft.
Table 9-7 gives the pressure groups for a single dive to various depths; the pressure group might be anywhere between Z (25 to 35 ft) and F (130 FT) for NDL dives. Table 9-6 then says the time-before flying is 7:06h (PG F) to 21:01h (PG Z). All for air dives.
These are not quite desaturation times, which according to Table 9-8 are 7:08h (F) to 15:50h (Z). Odd.

 

[tursiops]

Look out, the grammar police have turned up!

Fixed That For You.

 

[Fastmarc]

Not really of much interest because Suunto is known to use it's own propitiatory algorithm, which is also known to be extraordinarily conservative. That alone explains the additional 4 hrs past 24. Hard to argue that it would be unsafe when tons of other computers would say 24 for the same thing.

How could we know what other computers would say? He had only one computer with him that knew his exact profile for all of his dives.
Even if Suunto is thought to be a conservative computer, it knew his exact dive profile and calculated the desat based on that. I personally would only refer to DAN's recommendation if I wasn't using a computer, so had no real ability of tracking my deco stress.

 

[Graeme Fraser]

They also say to use 8000 ft altitude if you are flying in a commercial aircraft.
Table 9-7 gives the pressure groups for a single dive to various depths; the pressure group might be anywhere between Z (25 to 35 ft) and F (130 FT) for NDL dives. Table 9-6 then says the time-before flying is 7:06h (PG F) to 21:01h (PG Z). All for air dives.
These are not quite desaturation times, which according to Table 9-8 are 7:08h (F) to 15:50h (Z). Odd.

Indeed.

Again, aimed at a different demographic and operating sphere.

The tables also specify procedures for surface decompression on O2 using the 'bend and mend' approach. However, no way I'd consider deliberately blowing straight through all required deco, striping and jumping into a chamber as part of my standard routine.

 

[seeker242]

How could we know what other computers would say? He had only one computer with him that knew his exact profile for all of his dives.
Even if Suunto is thought to be a conservative computer, it knew his exact dive profile and calculated the desat based on that. I personally would only refer to DAN's recommendation if I wasn't using a computer, so had no real ability of tracking my deco stress.

The thing here is no computer anywhere has any ability to actually track deco stress. It’s a theory, aka a guess, based entirely on the algorithm. We know a bunch of other computers wouldn’t show that because we know they use less conservative algorithms. To assert that only the most extremely conservative computer, is the only one that’s safe, well that’s just nonsensical.

 

[tursiops]

It’s a theory, aka a guess,

A common misunderstanding of what a theory is.