Gerhard,

Thank you for the reply. It's good to know you are still monitoring
RAS.

I have included my comments below:

As a consequence, we explicitly recommend *against* using
a TIS-speaking device as the sole FLARM display in an installation.

Accepted. The 396 is used in my PA28-180 and the FLARM Portable will
also be in view.

We've been in touch with Garmin at the Aero in Friedrichshafen
and invited them to implement the open FLARM specific protocol on their devices. *Feel free to ask Garmin about an ETA!

Thanks for trying.

Layout of the screen is entirely determined by the display, and there are
probably dozens which implement TIS. * FLARM has no influence on that.

Understand - thanks

2. The displayed altitude is usually 100ft lower that that displayed on the FLARM screen.

May be a rounding issue, I'll check the FLARM part.

Thanks for checking


3. Perhaps most concerning - the non-direction traffic symbol is never displayed if there is any other traffic (ADS-B or FLARM) being displayed, even if the non-directional target is the closest in distance and altitude.

You probably only had 'informational' (non-threat) targets. *FLARM *will* send the non-directional target on TIS *if* it is more dangerous than FLARM or ADS-B traffic
around. *In case of non-threat traffic (the most frequent case and what you're
probably seeing) is that there's no threat traffic. *In this case
we do indeed prioritize directional targets. *The reason is, again, a limitation
of the TIS protocol.

Yes, all the target were "informational". However I think the reason
the non directional targets are not displayed is related to this
statement "The TIS protocol is limited to 8 targets maximum".

The manual for the Garmin 396 describes the supported TIS symbols.
There is no non-directional symbol specified. Not surprising since
TIS would have no reason to send that information. It appears that
the FLARM transmitted non-direction target is made up of 8 separate
target symbols. If that is the case then all the available targets
are used up if a non-directional target is transmitted.

Would it be possible to modify the protocol to allow simultaneous non-
directional and directional targets. Possible solutions could
include:

1. Alternate between display of non-directional and directional
targets on each data transmission.
2. Progressively reduce the number of symbols used in the non-
directional target symbol and allocate each of the freed symbols to a
directional target.

*TIS devices may have their own horizontal and vertical range settings, did you check?

There is no user defined vertical or range TIS setting in the Garmin
396. Several times. when a non-directional target was displayed, an
ADS-B target replaced it when the non-directional target did not
increase in altitude or distance. Also, I have a second FLARM
system. As soon as the second FLARM system provides the system under
test with a FLARM target the non-direction target is removed.

Best regards,

Andy