The problem that Garmin is working is different than many of us are experiencing. I think whats happening is that the G3X can’t display traffic from more than one device at a time, and it prioritizes a device based on a fixed set of rules. ADSB (GDL-xx) wins when both air to air and TIS-B are being received. But with ADSB air to air only, then TIS-A (from the transponder) takes priority when it’s present. The problem is that TIS-A only includes aircraft with mode A or mode C transponders, which are now very few. So, it appears like all traffic is lost. The option is to disable TIS-A in the transponder if you are running a GDL-xx and have a TIS-A capable transponder like the GTX-23-ES.
This is part of a post by G3xpert back in 2016:
A couple of things to check.
We know you have a GDL39, a GTX 330ES transponder, and a GPS 20A installed with your G3X system, so you actually have two traffic receivers. You receive TIS-A traffic from your GTX330ES and ADS-B traffic/weather from your GDL39.
As you probably know from the pilot guide and our
past postings, if both of your traffic receivers are enabled, the G3X system will prioritize them and use one or the other depending on which might be providing the best traffic information.
G3X Traffic Priority
1. GDL39/39R ADS-B traffic system receiving both air-to-air and TIS-B
2. GTX23ES/GTX330ES TIS-A traffic system receiving TIS-A
3. GDL39/39R ADS-B traffic system receiving only air-to-air
You will note that full ADS-B traffic with TIS-B ground uplinks takes priority over GTX330ES TIS-A traffic, but for those probably rare times when you are receiving TIS-A traffic and not TIS-B traffic, the TIS-A traffic takes priority and this traffic does not include Flight ID.
Many of us disable TIS-A traffic on the Mode S transponder (I did this in 2012) because ADS-B traffic is almost always better and we don't like ever seeing the system switch to TIS-A traffic. You might do the same (via the transponder configuration on the GTX330ES) to keep things simple.
Secondly, and probably more importantly, you might want to check your Traffic settings for the Map page. From the MFD map page select Menu, Set Up Map, and then select the Traffic Map Setup page.
From this page you may separately control the map range dependent declutter settings for the traffic symbol and traffic label (Flight ID). The default setting is Auto which will remove the traffic symbol and label at MFD map range settings of 12 nm and above. I personally find this Auto decluttering too aggressive, and change mine from Auto to a fixed 30 nm on both to keep the traffic symbol and label visible on the map even when zooming out quite a bit.
Another tip. The two traffic symbol icons on the upper right of the map which show if you are receiving TIS-B ground uplink services and air-to-air traffic also declutter (are removed) when the traffic indications are removed from the map, so this is a quick and easy way to tell if your map is zoomed out so far that traffic has been removed to decrease map clutter.
Thanks,
Steve