As the referenced article reminds me, there were some controlled experiments in the U.K. years back that empirically debunked the popular wisdom that Day-Glo tips and tail significantly enhanced visibility at a distance. This followed the movement in the mid to late 1970s when German gliders started arriving in the U.S. with orange/red tips and checkerboard tails. This trend seem to die out later as the evidence mounted that the high-viz paints didn't always help and, in fact, could hurt. I recall reading about experiments with mirrored coatings and black underside paints, two things that did seem to help in some circumstances. But it's dangerous to assume that what looks highly visible on the launch grid or close by in a thermal will work equally well at a distance, in particular on a collision course.

I'd argue the "big sky theory" (however one defines it) is still valid. What's undeniable is the probability that however remote, the odds of an encounter with another aircraft in that big sky are not zero and the consequences of that tiny probability are so devastating that it's worth seeking ways to reduce the risk.

I'm not current on the origins of FLARM but I seem to recall one of the drivers was the concentration of gliders along certain mountain ranges and ridgelines in the Alps, coupled with myriad cables and towers that posed a danger to low-flying gliders (I believe that was the reason for the obstruction database provided for in FLARM).

I suspect the only time we see that kind of concentrated traffic here in the U.S. is around major airports/airways/navigational features (where we either can't fly anyway or most pilots fly with heightened awareness and concern) and at large soaring contests, the size of which has diminished over the past 30 years. Nephi--which will almost certainly be oversubscribed--looks to be the exception to that.

One final not-quite-apocryphal story: back in the days of 65-glider national contests, I recall one attended by a pilot in a brightly colored Finnish glider. The pilot was thought by many to be particularly aggressive in thermals, so much so that a sighting of the "yellow PIK inbound" was often enough to prod even the most quavering, unapologetic leech to roll out on course in alarm. I don't know if yellow is the best color for visibility but against the background of Midwestern farm fields, it stood out pretty well.

Chip Bearden