Jonathan, I do understand your concern. I've seen the fin strobe on an ASG-29 several times, once at Mifflin running ridges on an showery, overcast day with him coming towards me. The strobe was visible, but not that helpful IMHO until he was quite close, and by then I'd already seen the plane itself because of Flarm. YMMV, of course, so my best advice is for you is to do the experiment. Set one up along a straight road on a gloomy day and figure out the distance when it becomes obvious.

-John, Q3

On Tuesday, January 24, 2017 at 11:15:27 AM UTC-5, Jonathan St. Cloud wrote:
Hi Debbie: I do not know if any studies have been done as to the visibility, but a strobe that is 12 long does put out more of a visual signature than a single point of light, as on most powered aircrat. Imagine, not a bright sky but running under a (dark developed )cloud street at 110 knot IAS at 17,000 ft with another glider flying in opposite direction, same speed. The Flarm goes off and so does the strobe, will that 12 inches of strobe give off enough to catch the eye of the other pilot? That strobe sure is bright, and I have had people tell me that it really stands out. It seems as if the 12 inches of strobe is much more visible than a single point of light.