Sunday was the best gliding day so far this year. In terms of weather. Obviously and very sadly not for those involved in the mid air near Abingdon. I would guess that a large proportion of the UK glider fleet (c. 2500) was airborne on Sunday and a fair proportion of them in the southern England area OCAS. See
Daily Scores for those that logged their cross country flights - and that is by no means all who did cross countries on Sunday. And look at the distances flown -
sans moteur.
I suspect there were a great number of GA aeroplanes also in the height band 1000 - 5000 ft AGL, below cloud base.
What this shows is that Sunday was the equivalent in road traffic terms of a sunny bank holiday weekend on the M5 to Devon - crowded. So statistically one would be more likely to encounter more than the odd aircraft en route.
Now even the proponents of using any ground based advisory radio or radar service in Class G will quickly realise that with (a) the speed at which the high volume of airborne traffic is moving (b) the delay factors contacting and getting a response from the ground based third party (c) the overload factors on a ground based person (d) the fact that gliders do not follow a straight line necessarily and are constantly ascending / descending, then it is impossible to have a fool proof ground based human third party intervention system to keep us all apart.
So the quickest means to do so is constant lookout.
Backed up by Flarm or something similar. I have flown with Flarm for 4 years now - mostly in the French Alps - and I can say with confidence that it reduces risk but of course will never eliminate it. The price is worth the extra mitigation.
As to conspicuity, there have been various experiments conducted over the last few years with regard to making white gliders more visible. None have proved conclusive of a better scheme, other than the RAF black (which of course we can't paint our gelcoat gliders with, for reasons already given in this thread). Even orange dayglo strips and markings on the wings do not work that well. In fact my French colleagues - with many '000s of hours mountain flying - say that often these markings break up the profile of a glider against the mountain / snow background, with the result that the aircraft becomes a smaller profile. This I experienced first hand last month high in the Alps when the Flarm gave a 'three reds' alert. Neither my co-pilot nor I could see another glider until it passed close in front and underneath us as we thermalled. And the other glider was covered in dayglo strips. BTW my eye test last week was A1....I write as someone with 40 years' gliding, 2700 hours and some power flying. I intend to do a lot more as well, looking out and hoping I see everything. But I won't rely upon third party sources on the ground for this.