On Sunday, January 3, 2016 at 8:51:19 AM UTC-8, Darryl Ramm wrote:

You get TIS-B for transponder equipped aircraft and only those not equipped with ADS-B Out (but obviously you get those with ADS-B direct or ADS-R which is even more accurate/better coverage) and you don't see ICAO codes for Mode A/C transponder equipped aircraft or those with UAT Out in anonymous mode.... so you won't necessarily be able to tell which glider/contest ID etc.


The point being that one ADS-B Out equipped glider will light up (within a 15 nm radius) all transponder-equipped contest gliders in range of SSR with pretty decent resolution (but no ICAO ID unless Mode S). They should be visible not just to the pilot with ADS-B out, but to anyone with ADS-B In-equipped PowerFlarm - so long as the glider with ADS-B Out is requesting 1090ES transmission for TIS-B traffic - which ought to be the case since I doubt gliders would equip with UAT In only.

A small number of gliders out on course so equipped and reasonably spaced ought to light up pretty much everyone on task equipped with a transponder and within a 7,000' altitude band.

Not sure what the percentage of racing gliders equipped with transponders is - but I suspect a lot.

9B