<html>
<head>
<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
<div class="moz-cite-prefix">On 26/07/2016 15:53, Dirk Hohndel
wrote:<br class="">
</div>
<blockquote
cite="mid:A3CDA2F9-1900-48EF-A971-B65E1037085E@hohndel.org"
type="cite">
<div>
<blockquote type="cite" class="">
<div class="">On Jul 26, 2016, at 6:16 AM, Robert Helling <<a
moz-do-not-send="true" href="mailto:helling@atdotde.de"
class=""><a class="moz-txt-link-abbreviated" href="mailto:helling@atdotde.de">helling@atdotde.de</a></a>> wrote:</div>
<br class="Apple-interchange-newline">
<div class="">
<meta http-equiv="Content-Type" content="text/html;
charset=utf-8" class="">
<div style="word-wrap: break-word; -webkit-nbsp-mode: space;
-webkit-line-break: after-white-space;" class="">Hi all,
<div class=""><br class="">
<div class="">
<blockquote type="cite" class="">
<div class="">On 26.07.2016, at 14:30, Robert
Helling <<a moz-do-not-send="true"
href="mailto:helling@atdotde.de" class="">helling@atdotde.de</a>>
wrote:</div>
<br class="Apple-interchange-newline">
<div class="">
<div class="" style="font-family: Menlo-Regular;
font-size: 12px; font-style: normal;
font-variant-caps: normal; font-weight: normal;
letter-spacing: normal; orphans: auto;
text-align: start; text-indent: 0px;
text-transform: none; white-space: normal;
widows: auto; word-spacing: 0px;
-webkit-text-stroke-width: 0px;">I haven’t had
time to read in the proceedings of the DAN
workshop that was linked before. What I saw that
came most closely to a recommendation was a
report of a plan to do a study trying to bend
subjects in a simulated fly after dive scenario.
Which is not much that could be put into
software. Maybe one should check the Rubicon
Archive for more scientific information on the
issue.</div>
<br class="Apple-interchange-newline">
</div>
</blockquote>
</div>
<div class=""><br class="">
</div>
ok, I did some Rubicon search and follow up reading an
the two most relevant papers seem to be </div>
<div class=""><br class="">
</div>
<div class=""><a moz-do-not-send="true"
href="http://archive.rubicon-foundation.org/xmlui/bitstream/handle/123456789/6255/SPUMS_V9N3_4.pdf?sequence=1"
class="">http://archive.rubicon-foundation.org/xmlui/bitstream/handle/123456789/6255/SPUMS_V9N3_4.pdf?sequence=1</a></div>
<div class="">and</div>
<div class=""><a moz-do-not-send="true"
href="http://archive.rubicon-foundation.org/xmlui/bitstream/handle/123456789/5611/DAN_FAD_2002.pdf?sequence=1"
class="">http://archive.rubicon-foundation.org/xmlui/bitstream/handle/123456789/5611/DAN_FAD_2002.pdf?sequence=1</a></div>
<div class="">(in particular the executive summary).</div>
<div class=""><br class="">
</div>
<div class="">Upshot seems to be: Very hard to asses given
the low number of cases (boarding a place when you
already have DCS symptoms seems to be a totally
different game, though), but 12-18h limits, maybe 24h
seem to be a good idea and there is no model on the
marked that is able to predict this.</div>
</div>
</div>
</blockquote>
<br class="">
</div>
<div>This seems to match my expectations.</div>
<div>a) made up random shit</div>
<div>b) semi-scientific algorithms, tuned by random numbers
without any scientific basis in order to match pre-conceived
notions of "this sounds about right"</div>
<div><br class="">
</div>
<div>/D</div>
<br>
</blockquote>
Be fair, it's a hugely multidimensional problem that is not easily
tractable. The DAN project at experimental decompression to 8000 ft
had pretty low sample sizes but there was (if I recall correctly)
one serious case of DCS in the order of 12 h after repetitive
diving. Was it just a single individual response? Really part of a
pattern? Difficult to say. I would say a first-level approach is to
use the standard models we have and predict saturation levels when
flying after various surface times. Question is, what cutoff level
of PN2 (or bubble size) indicates safe flying condition? Given this
lack of understanding, if a recreational diver, diving 6 dives a
year, with no understanding of PN2 and how to manage it, asks me
this question, I would probably use the guess of 24h before flying.
This diver does not understand the complexity of the problem and
wants an answer. For DAN there are potentially real costs related to
the consequences of their advice, so I understand their point of
view.<br>
<br>
In the past we have made extensive use of the NOAA table for
surface-time-before-flying. But I have no idea what the basis was
for that table and we often forget we have to take it with a pinch
of salt.<br>
<br>
Alternatively, we sometimes plan the last dive(s) to do deco as if
we are doing the dive at the maximum altitude we will experience. I
do this when I need to cross mountains of 2000m altitude to get home
after waiting and additional 2 h. We have not had incidents yet, but
we hardly have a large sample size upon which to base such a
practice.<br>
Kind regards,<br>
willem<br>
<br>
<br>
</body>
</html>