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#19
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![]() 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 |
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