Good Drs., an opinion please...

[DeepSeaDan]

Greetings,

Am planning a two-dive day for some d.m.c.'s, one of whom is a police officer whose current duty is as an observer on a police helicopter ( I believe they have a ceiling of 5000' for their ops. ); question: Would he be safe to fly ( flying is "on call" - they go up as needed over a 12 hr. shift... ) after this itinerary:

> Dive #1: 1000 hrs, depth range - 90' -100', TBT - :25 Mix: 31% N2O2
> S.I.: Min. 1 hr.
> Dive #2: 1145 hrs., depth range - 60' -70', TBT - :40 Mix: 31% N2O2

His shift begins @ 1800 hrs., same day.

I can't see him having sufficient N2 onboard to be of concern; then again, expert opinions hold sway!

Thanks!

Regards,
DSD

 

[tbone1004]

At 5000ft you're at .83atm
Equivalent of dive at 27feet with ascent to the surface.
You're EAD's are 83ft and 57 ft, blow the navy tables out of the water, but take a liberal deco stop or breathe O2 at the surface for half an hour and I can't imagine anything bad would happen.

That said, I don't think the actual doc's can say anything though because of liability and saying that flying after diving isn't recommended within 24 hours...

 

[DocVikingo]

Never mind.

Regards,

DocVikingo

 

[DeepSeaDan]

Sorry - my cop-buddy has informed me their ceiling is in fact 2000', not 5000' as previously mentioned...

DSD

 

[bleeb]

One reference I find interesting is the NOAA Required SI Before Ascent To Altitude Table. (Make sure you use the pressure groups from the NOAA dive table, adjusted for appropriate EAD, and not from someone else's tables. Found on the same page.)

At the risk of contradicting the other posters in this thread, taking your dive plan as square profiles, it looks like he might be pushing things just a bit and could use a few more hours of post-dive time. Shallowing up and shortening the second dive by even just a few minutes decreases recommendations considerably.

Edit: Just saw your update. 2000' would help a lot, but there's a possible risk to be considered. What are the chances that some event (or Air Traffic Control) forces them higher? Not a yes/no issue. Also, your student might want to check whether there are any departmental regulations regarding flying and diving, such as the FAA has for pilots. Hopefully this doesn't open any cans of worms for him.

 

[tbone1004]

I was going based on the NOAA recommendations and even with that dive profile, he ends up as an L diver on the navy/noaa tables. At 5000 ft it's not recommended, but at 2000 ft it recommends just under 6 hours, which he has.
Those are at the deeper depths.
If you can curb that last dive to under 34 minutes it saves him a whole lot.
Or up the SIT to 1:15 and you do the same thing

 

[DeepSeaDan]

We can certainly make adjustments, the numbers I offered up were at the higher end.

Good point on possible restrictions imposed by the employer, will look into that.

Noe he's telling me he's gonna book the shift off! Now there's a good solution; even so, it's been an interesting exercise - thanks again.

Regards,
DSD

 

[boulderjohn]

For anyone flying at an altitude less than 2,000 feet, you may want to consider this quotation from the executive summary (pages 12-13) of the DAN Flying After Diving report:

Finally, a minimum threshold altitude below which guidelines were unnecessary was discussed. Although no data were available that specifically addressed the question, a previous publication had suggested that restrictions were unnecessary below a threshold altitude of 2,300 feet (701 meters) (15). The U.S. Navy Diving Manual had followed this recommendation without apparent problem until introduction of the 1999 procedures that reduced the threshold to 1,000 feet (305 meters) for internal consistency (5). The workshop participants agreed that 2,000 feet (610 meters) was a reasonable, if uncertain, threshold, as no problems with 2,300 feet were cited.