GTN 750xi Displays FIS-B TFR No Data

[PeytonM]

Why no TFR data message? Software, hardware or simply no TFR data being broadcast?

[PT20J]

A few points about FIS-B NOTAM-TFR

1. They are only transmitted every 10 minutes. (AIM 7-1-9 TBL 7-1-3). 

2. The look ahead is 100 nm which means that a ground station will only transmit TFR that are with 100nm of the antenna. (AIM 7-1-9 TBL 7-1-4)

3. Garmin had a bug where TFRs that persisted  more that one day were displayed only on the first day. So, make sure your software is up to date.

You can get more information about what the GTN is receiving by accessing the Weather page from the Home screen and selecting FIS-B Weather. If you tap the FIS-B display in the upper right corner it will expand the age of the TFR data. Also from the FIS-B Weather page you can get more information by pressing Menu and then Datalink Status. From the Datalink Status summary page, you can press Menu again and then Radio Stations. The Radio Station page allows you to see which ground stations are being received and what has been received from each. Each ground station transmits a Current Report List (CRL) but the GTN combines the CRL from all stations being received into a single CRL at the top of this page.

Note if you are comparing TFR data between ForeFlight and the GTN that ForeFlight caches data received from the Internet and only overwrites cached data if it receives new ADS-B data. So, ForeFlight may show more TFRs that the GTN because of the FIS-B look ahead limitation. I don't know if Garmin Pilot works similarly.

FIS-B and ForeFlight both use tfr.faa.gov as a data source and I have found ForeFlight very reliable in depicting all active TFRs. Because it can take up to 10 minutes to receive TFR data, the GTN may not show a nearby TFR immediately after takeoff until too late.