I tend to agree with Andy here.

I see an all too familiar pattern of people taking positions and having
heated personal debates that tend to miss the point.

So - applying some consulting skills:

I believe the original poster was of the opinion that the number of
contestants has a direct correlation with the relative safety of an
event. Various motivations for the perceived correlation were advanced.
Some relating to exogenous factors like weather and geography, and some
internals - predicting that behaviour will be influenced by the
competitive situation and lead to dangerous flying.

Unfortunately there is no way to directly test and disprove the thesis
(and the scientific method is that you can't prove a thesis - the best
you can say is that there is evidence to support the thesis and it has
not been proven wrong yet)

In most cases I see a lot of anecdotal evidence or opinions advanced to
prove or disprove a conclusion drawn from limited experience. One of the
big problems we have with this is misattribution - take an opinion or
speculative position and look for the first correlating fact we can
find.(never mind about whether there is any known / proven causal link)


So - I urge people to think a little before ascribing causal meaning to
things that merely correlate. Much more I wish people would discriminate
between
- a concern - that's a lot of people flying together, I hope nobody gets
hurt.
- a thesis - we postulate that there is a statistically significant
correlation between the number of contestants in any contest and the
risk per flying hour of an incident.
- speculation - I wonder if it is dangerous to fly in a group event with
more than 20 pilots participating?
- conjecture - there have been accidents at contests involving lots of
pilots so I conclude it is dangerous for lots of gliders to launch in a
short period of time.

A lot of the time people mix these all together, and it becomes very
difficult to work out what they actually think they are saying, let
alone what they meant...

Just saying - it might make things easier if we were more explicit about
things and think before we, for example, accidentally present
speculation as fact.

In that spirit, let me indulge in a little mind experimenting.

In my limited experience flying camps, contests and general stuff and as
a long time safety officer, I have observed the following:

Does the concentration of aircraft and activity in a relatively
constrained volume of airspace make for more danger from mid-air
collision , or ground collision or loss of control due to avoidance due
to the higher proximity?
My experience says the contrary. In a busy event there is a heightened
awareness of proximity and situational awareness tends to be excellent
due to the communication efforts of the organisers and participants. The
occasional mistake still happens, but from an accident history, I have
seen fewer incidents at busy events as opposed to the quiet days.
Similarly, it seems there is less danger when everyone is focussed on
the same thing, and generally on a similar task - so the combination of
bad task setting and concentration of participants might cause problems,
but in my experience the organisers do a good job of making
non-conflicting routes.

Does the absolute number of contestants correlate directly with risk? My
experience is that we each manage our risk according to our personal
comfort levels and capabilities. Busiest gaggle I have ever personally
been in had 36 gliders stacked in a 9,000" deep cylinder at the start.
Every time a tug dropped anyone - they would make a beeline for the
bottom of the "big" thermal. When they started crowding around at the
top, people started leaving. The very experienced pilots fought it out
to the top, but they would be doing the same if there were only 2 or 4
of them ...

We could go on for a long time - but enough to say that there is little
empirical evidence that the number of participants relates directly to
risk. What I have evidence of is, that for any particular facility and
available resources like tugs and ground crew - there is a point beyond
which risk will increase. If you are not leaving anywhere for a relight
landing, or there is nowhere safe to run out on the runway, or there are
points where aircraft will approach with significantly different tracks,
then you have to start doing something to manage the risk.

So -
I think you can find evidence where the organisation's failure to plan
or organise around the number of participants has resulted in accidents.
I think you will find evidence that failing to avoid conflicting flight
paths will result in increased danger. (It only takes two to make a
midair) and it is easy to find evidence that task setters avoid this.
It is easy to confirm that the general experience level and relative
safety maturity of the participants in such an event is well above
average. I could speculate that this is because the inexperienced wisely
elect to avoid them, or because they are more attractive to the
experienced pilot.
I think you will find evidence that "big" events are generally safer per
flying distance or time, than general operations.

The fact that there are lots of people flying lots of km over
consecutive days naturally concentrates the number of reported
incidents, but my conjecture (based on experience but not hard numbers)
is that it does so generally in a less than linear ratio to the same
group of pilots in general operations. So it is perhaps safe to assert a
thesis - I believe that there is a higher probability that an accident
or incident will occur during a contest because of the amount of flying,
but that on most meaningful metrics it is actually safer to fly in such
an event than to fly the same number of flights/cross country km and/or
time in general operations at the home field.

The sheer number of safely concluded contests is testimony to this - but
it is an unproven thesis.

So to come back to the OPs point.
If there were 20 more pilots competing at Nephi - would the statistical
probability of a reportable safety event increase?
Answer - of course it would, but probably in a diminishing ratio.

Would an accident at Nephi prove that the grid was too big and that the
accident would not have happened if the number (n) was limited to say 40?
Answer - Since it only takes one glider on one flight to have an
accident, and the number of accidents at any site is so small, it would
be practically impossible to make a statistically valid model that
supports this thesis except for the edge case where n=0.

More pertinently - would adding "n" additional aircraft to the grid
increase individual risk for the existing participants?
Answer - Personally I doubt it.(trivially it increases the risk for the
new participant)

Lastly - Is there a maximum number of pilots who can compete in an event
with guaranteed safety, and that you can prove that more than this
introduces risk?
Answer - Of course there is - the number is ZERO. Above that, the answer
is "It depends".

This winter weather is clearly getting to me...

Bruce --
Bruce Greeff
T59D #1771
--
Bruce Greeff
T59D #1771