Speaking of which, I was wondering if PF can accept a TIS input from the likes of a Zaon XRX and then output the combined traffic (Flarm / Mode C) onto one display?
PowerFLARM has its own Mode A/C/S/ADS-B detector, that’s the difference between PowerFLARM and FLARM. I have connected my PowerFLARM to my Garmin GPSMAP695 and see all targets there. It works very well without any problems.
Are there any FLARM receivers whose output can be merged into the ARINC429 data stream coming out of a TAS605 or similar TCAS box (in a manner similar to what I believe a GDL88 can do with ADS-B data) and which come with an FAA STC?
No, PowerFLARM/FLARM is not certified.
But I guess PF doesn’t show azimuth of the Mode C targets, just range? Zaon shows azimuth, height and range (position on the map). Can you give me an idea of what the transpoding targets show up like using PF? Thanks.
PF shows a circle for Mode A/C/S targets and a position arrow for ADS-B targets, both with a number showing relative altitude in hundreds of feet. I believe Zaon mostly pretended to be able to show position but the margin of error was so large that it wasn’t really useful. I am OK with how PF displays these targets, the range, the relative altitude and how that changes over time. Typically I am able to spot targets rather quickly (or see that they moving away and don’t bother).
At this point I rather have a PowerFLARM with imperfect transponder detection and a FLARM than having a TAS without FLARM. Both systems would be ideal of course but TAS systems are way too expensive to my taste.
ZAON resolved the azimuth into four 90-degree segments, but from what I have seen it suffered so badly with spurious detections that you could not rely on it all that well.
POWERFLARM gives no azimuth information at all on Mode A/C targets which currently form the vast majority (at least 99% – except in unusual locations) of GA aircraft.
So we don’t really have a good solution at present.
I spoke to PF and they were totally uninterested in doing azimuth but then ZAON were still in businessat the time.
The first product which delivers something properly integrated (certified or not) is going to clean up the market. However, there is no trivial way to do azimuth on Mode A/C/S.
FWIW, I consider the £12k spent on my TAS605 to be money well spent. It probably has not saved my life yet but it definitely has avoided some very near misses, low level in the UK, and in the circuit especially. It’s a pity these boxes are so expensive. Are there any cheaper ones for homebuilts, incidentally?
When my PowerFlarm shows a mode a/c target without azimuth nearby, let’s say with a delta altitude of 200ft and I don’t see the traffic, then I climb or descend +/- 300ft to
reestablish some more vertical separation hoping the other aircraft has the proper altimeter setting 
Collision avoidance can only be done on the vertical scale. Even the highly sophisticated TCAS work this way; the builders say they are unreliable in azimuth.
I climb or descend +/- 300ft to reestablish some more vertical separation hoping the other aircraft has the proper altimeter setting
Transponder altitude is flight level so you only have to hope that the last static test was done by somebody competent I do it exactly as you described and this is why I think PowerFLARM is sufficient and the benefits of an expensive TAS are limited.
The transponder does indeed radiate the pressure altitude (altitude with a QNH of 1013) but any system displaying traffic relatively to you ought to be correcting it for that.
I guess the portable systems can’t do that – unless they have a barometer (in which case you have the problem of the cabin altitude being anything up to 200ft different from the outside) or you set the QNH (whose QNH…?).
Even the highly sophisticated TCAS work this way; the builders say they are unreliable in azimuth.
I think there is a historical/regulatory component to that i.e. airliners are allowed to change only altitude, to avoid traffic. That is the TCAS II protocol, I believe.
It doesn’t mean that the azimuth is actually wrong. It can be, especially for close-in traffic (under say half a mile) but usually it is spot on unless the installation is bodged. If you do avoid based on the azimuth, you have probably a 90-95% change of improving the separation even if you stayed at the same level. So it’s worth doing, IMHO.
Before I spent the 12k I too thought that TAS systems were a waste of money, especially in the circuit 
Now I am completely converted. The chief difficulty, in the UK for sure, is finding an avionics installer capable of doing it without completely bodging it and stripping half the screws in your plane…
I guess the portable systems can’t do that – unless they have a barometer (in which case you have the problem of the cabin altitude being anything up to 200ft different from the outside)
PowerFLARM has its own barometer and I have observed the cabin pressure effect to be rather small. Level aircraft appear as level in my tests. Probably the same effect as pulling the alternate static air switch and watching your altimeter. I can see the needle jump but hardly a difference of more than 20ft.
Before I spent the 12k I too thought that TAS systems were a waste of money, especially in the circuit Now I am completely converted.
Until you can see the red in the eyes of a glider pilot I might have bought a TAS, too but flying without FLARM is something I wouldn’t do anymore. Too many of them, too hard to see.
I’ve had quite good success with the Zaon XRX showing position. It is mounted on the glare shield and wired to a Garmin Aera 550. In the front 270 deg it pretty accurately depicts traffic.
I presume the PowerFlarm Mode C circles expand and contract depending on the range? If so I can see that that is quite useful to determining proximity and as you say, altering altitude will avoid a conflict.
for all PowerFLARM owners I can recommend the interior flarm antenna for 39,90€ – I was able to find a place to mount it vertically (on the side wall of the TB20 center radio stack on the glareshield) – the PF now shows the targets earlier (mostly flarm equipped gliders) – ADS-B and Xponder traffic depiction works well with the already built-in antenna on the PF as the signal strength is stronger.
