On Friday, June 21, 2013 12:31:22 PM UTC-7, wrote:




Doesn't having a transponder also alert the Flarm unit/user?







Mike



Mode S will tell every flarm in miles where you are. Mode C is next to useless for flarm, and many flarm people will have turned mode c warnings down/off.



John Cochrane

Uh? I am willing to listen to economic advice anytime from John but I suspect there is some confusion here and he likely means 1090ES ADS-B. Which is an option on most modern Mode-S transponders but just having "Mode S" does not imply that aircraft transmits 1090ES.. and few especially GA aircraft will today. A threat aircraft with 1090ES data-out will show up with precise location/altitude data on your PowerFLARM, its no longer a PCAS threat with altitude only info. A Mode S (or Mode C) alone transponder in a threat aircraft will only ever present as an altitude only PCAS threat.

There are other compilations with Mode S vs. Mode C. With Mode S a PowerFLARM receiver could in principle do better de-duplciation of threats if that threat aircraft has both Flarm and Mode-S and the Flarm is properly set up to transmit the same unique ICAO address as the Mode S. (then your Flarm receiver can see both the Flarm and Mode-S signals come from the same aircraft). How well PowerFLARM does this in practice I can't comment on.