On Sunday, February 22, 2015 at 12:24:44 PM UTC-8, Mike Schumann wrote:
It is NOT impossible to design system upgrades so that they are backward compatible with older units that are still in use. It is probably much more convenient for FLARM to use this approach so they don't need to deal with the complexity of having multiple different device versions that need to talk to each other. These kind of shortcuts make one question whether FLARM really has the potential to be a VERY niche product for a small subset of the aviation market.

Couple that with POWERFLARM's inability to see UAT equipped ADS-B OUT equipped aircraft, either directly or via TIS-B retransmission from an ADS-B ground station, raises some big questions on whether or not they have really thought thru the whole collision avoidance picture in the US, where the threat is not just other gliders, but also GA and airline traffic.

Please - anyone with a little knowledge of systems or control theory can tell you that maintaining full backward compatibility, while possible, is a boat anchor in terms of system performance. The Flarm folks made a prudent tradeoff to maintain overall system integrity and performance while enabling periodic improvements in algorithms that depend critically on timing. I, for one, am glad they made that choice.

This UAT ADS-R and TIS-B argument is growing increasingly tiresome. There's virtually no UAT-Out traffic out there when compared to Flarm and 1090ES-Out and certainly not when compared to what shows up on PowerFLARM's PCAS.

The numbers of aircraft equipped with different types of equipment, what equipment can see aircraft equipped with what other equipment and the scenarios where variously equipped aircraft come into proximity with each other has been analyzed in detail and the unavoidable conclusion is that the LAST piece of gear glider pilots should consider is ADS-B UAT Out - after PowerFLARM, after a transponder (preferably Mode S) and, maybe 5-10 years from now, after upgrading to 1090ES Out. It remains to be seen whether significant numbers of aircraft are going to equip with UAT Out in the GA community since 1090ES Out is the single standard for Europe and for anything that flies in Class A in the US. It may just steamroll UAT Out.

I agree with Kirk - misrepresentation of facts about systems that are important to safety is irresponsible. These arguments have been discredited on the facts and rejected overwhelmingly by the soaring community, the marketplace and the leadership of the SSA.

9B