TIB-B

What exactly prompts this TIS-B symbol.  I know it means TIS-B is not being received but I seem to get it for quite a bit of the time on my flights and I seem to still be receiving traffic when it appears as seen on this screen.  I'm not sure how I'm receiving traffic with no TIS-B.  Does other traffic some from just ADSB?

On another note, I still get a warning of no datalink weather at the beginning of most flights and the alerts say no "sigmets" have been received.  I thought this was fixed with the last update.  Is anyone else still seeing this?

See http://www.avidynelive.com/forum_posts.asp?TID=1667&PID=20527&title=tisb-and-weather#20527

teeth6 wrote: ... the alerts say no "sigmets" have been received.  I thought this was fixed with the last update.

ADS-B weather data (FIS-B) contains a list of products that are to be transmitted, called the "Current Report List" (CRL).  Prior to 10.2.3.1, the IFD didn't check the CRL to ensure that a SIGMET was expected.  So, when a SIGMET was not received, the IFD would display an alert even if one shouldn't have been received. 

In 10.2.3.1, a change was made to inhibit the alert if the CRL indicated that no SIGMET was to be expected.  So, if an alert is being generated with the latest software, it's because the FIS-B stream is indicating that we should expect a SIGMET and we haven't received one.

I looked at the EX5000 log and it indicated receipt of TIS-B traffic (if I interpreted correctly).  I did not pull the log off the IFD-440, though.  

I have an NGT-9000 installed in my plane, it is not connected to the IFD440 for anything other than traffic at the moment as it replaced a GNS430W so the traffic was over ARINC 429, once I get an opportunity to visit the avionics shop I'll get that resolved. :)

What brought my attention was the post about no TIS-B coverage, the NGT-9000 puts up a little yellow satellite dish icon on the screen when it is not receiving TIS-B traffic and I get it on and off throughout my flights in the NYC area.  I recently did a flight from MMU to CGS and it was on and off throughout the whole flight and with the exception of the initial climb and descent I was at 8000 ft, certainly high enough to get coverage especially when I'm traveling between NYC and Washington DC.

I saw some comments about using the L3 NGT-9000, what other transponders are being used that are showing no TIS-B coverage?

I'm wondering if this is an FAA problem or a transponder problem.

Jeff

I have wondered if perhaps Avidyne could look into something similar in the logic of their TISB annuncation in the IFDs... maybe put that into a future update...

Doug

Was flying this Saturday early afternoon less than 15 miles south west of EWR at 2500 ft when I got the no "TIS-B" indicator on the 440, my transponder did not indicate a traffic failure.  I was going to pull out my phone for a photo but by the time I was able to do so the no tis-b indicator had cleared.  Since I usually use the transponder for traffic display I can't tell you if traffic was being displayed on the 440, I can confirm that I did have traffic being displayed on the transponder, I don't think any of it was TIS-B traffic, but rather "air-to-air" traffic.

If it matters, I do know that there is an ADS-B transmitter at EWR.

Jeff

Joh

You mean why *not*?  I guess we could, but it's good to have some indication showing the pilot that the data stream is not 100%.