From: pvf@alantec.com (Paul Fries)
Newsgroups: rec.skydiving
Subject: malfunction survey
Date: 6 Oct 92 00:46:59 GMT
Distribution: na


Contrary to earlier post, I am in today, although I will be
in and out over the next week or so on family business.

Here are the data as I have them so far.  Some of these
have obvious misunderstandings/mistakes.  Please EMAIL the
correct data to me.

Just so we are all counting and reporting the same thing, I
will restate the survey inputs.  That way, even if the data
don't turn out to be the best to collect, we won't be
comparing apples to oranges.

    1) I am counting for rigs equipped with square mains.
       If you have a square main and a round reserve, fine.
       This qualification serves to limit the survey to
       the "modern era" of skydiving.  It seems to me that
       we are more interested in what is happening in the
       present and more recent past, as opposed to the days
       of all surplus ex-military gear.

    2) The first number is total jumps

    3) The second number is "reserve rides".

    4) The third number is the number of reserve rides that
       were "avoidable".  That is, if the cause of the
       original mal was CLEARLY under the jumper's
       control.  This number represents some percentage of
       the reserve rides counted under item 2, above.

       Thus, an input line like:

		15000 0 1 <email address>

	has some sort of error in it.  And:

		15000 1 1 <email address>

	might represent a very careful jumper who once twisted
	a belly-band or leg strap (for instance).  And:

		15000 1 0 <email address>
	
	might mean his 15000 jump rig finally blew up! :)

Anyway, here are the input that I have received via email
so far.  Some were not formatted correctly, but I fixed
them up.  Many were formatted according to the request, and
I thank those people for they consideration.


4700	12	0	rgbonitz@ucdavis.edu
2000	5	2	jerrys@umiacs.umd.edu	
1500	0	0	ks@acn.purdue.edu
1350	1	1	artb@lsid.hp.com
1250	9	4	yzarn@chevron.com
700	1	0	bdaniels@ssf-sys.dhl.com
650	0	0	horn@mickey.jsc.nasa.gov
630	1	1	joe@avs.com
620	0	0	eric@tc.fluke.com
600	0	0	walter@austin.ibm.com
500	1	0	pvf@alantec.com
390	1	0	J.Mills@ma02.bull.com
358	2	1	belboz@frc2.frc.ri.cmu.edu
210	0	0	woycik@pa.dec.com
203	1	1	dianen@world.std.com
175	0	0	tjreynol@du.edu
169	1	0	jlfitz@genie.gene.com
160	0	0	dr25@andrew.cmu.edu
154	0	0	ruokonen@aapo.it.lut.fi
150	1	0	overbeck@vexpert.dbai.tuwien.ac.at
92	0	0	koning@koning.enet.dec.com
43	0	0	henchel@mentor.cc.purdue.edu
35	0	0	reimer@rintintin.Colorado.EDU
27	0	0	wilder@fml.arc.nasa.gov
7	0	0	crockett@technet.nm.org
3	1	1	loomis@fml.arc.nasa.gov

QUICK SUMMARY:

	   26 data points
	16676 total jumps
	   37 reserve rides
	   11 "avoidable" reserve rides

So, .22187574% of jumps end up with a reserve ride.  That's
less that 1/4 of 1 percent or about 1 reserve ride in 451
jumps.  Roughly a third of these were due to "obviously
avoidable" jumper errors.  Taking these out, our data say
that 1 in about 641 jumps ends in an "unavoidable" reserve
ride.

Sure, our sample is quite small, and there seems to be a wide
variation among the data points, but this is interesting
nonetheless.

I will continue to collect and repost occasionally.  As I
said, my schedule is going to be somewhat messed up in the
next couple of weeks, so bear with me.

Thanks,
Paul Fries
pvf@alantec.com

PS I don't know a lot about statistics, so don't flame me if
I did something wrong with the figures.  I am just trying to
write some of this stuff down so we can all look at it clearly.

later