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teeth6 View Drop Down
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    Posted: 29 Sep 2019 at 9:51pm
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?



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Post Options Post Options   Thanks (0) Thanks(0)   Quote HenryM Quote  Post ReplyReply Direct Link To This Post Posted: 30 Sep 2019 at 7:16am
TIS-B is broadcast traffic from a ground station. You can still see traffic that has ADS-B Out equipment and is broadcasting its position. 

The weather warning is just saying SIGMETS haven't been received in a while. That happens when there are no SIGMETS issued, or when you don't receive any ground stations. The latest software release allows you to clear the warning. Before, you couldn't couldn't clear the alert. 
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Post Options Post Options   Thanks (1) Thanks(1)   Quote AviSteve Quote  Post ReplyReply Direct Link To This Post Posted: 30 Sep 2019 at 9:33am
Originally posted by teeth6 teeth6 wrote:

What exactly prompts this TIS-B symbol?
See http://www.avidynelive.com/forum_posts.asp?TID=1667&PID=20527&title=tisb-and-weather#20527

Originally posted by teeth6 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.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote teeth6 Quote  Post ReplyReply Direct Link To This Post Posted: 30 Sep 2019 at 1:43pm
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.[/QUOTE]

Steve,

Interesting.  Thank you.  Yesterday was a perfectly clear, smooth day so I'm not sure why CRL would have indicated a Sigmet was to be expected but assuming that is the case, what are some possible reasons why I didn't receive it.  Once I get the alert, the Aux light stays lit the rest of the trip as it did before 10.2.3.1
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Post Options Post Options   Thanks (0) Thanks(0)   Quote daveS Quote  Post ReplyReply Direct Link To This Post Posted: 30 Sep 2019 at 4:42pm
I have dual 440's and a Lynx NGT9000 and get the 'NO TIS-B' very frequently.  I flew in the DFW Class B this past weekend for my BFR between 3-6K and pretty much had the 'NO TIS-B' message the entire 2 hours.   Traffic is being shown.  I've noticed this since my installation a couple months ago and had the avionics shop test things out recently with no installation/connectivity issues detected.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ansond Quote  Post ReplyReply Direct Link To This Post Posted: 30 Sep 2019 at 5:15pm
+1... Dual IFD440s and I'm now seeing many more "No TIS-B" messages... not sure why because nothing has been touched on my plane in several months... I'm wondering if there is an issue or change made to the ADS-B ground station system recently... odd that I'm seeing these in the Austin area and you are seeing them in the DFW area. 

A nice IFD feature enhancement might be to have an option (default would be disabled...)  to show the triggering exception condition in the alerts/logs so that the user can record them for later investigation/reporting... I could turn that on and then report exactly what sort of exception is being thrown to cause the message to display.

FYI, since receiving more of these messages I've re-run the PAPR report (https://adsbperformance.faa.gov/paprrequest.aspx)  on a few of my flights with no exceptions or problems reported/highlighted... so I'm not sure why the message is being displayed more now. 

Doug
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Edited by ansond - 30 Sep 2019 at 5:18pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote HenryM Quote  Post ReplyReply Direct Link To This Post Posted: 30 Sep 2019 at 5:27pm
Maybe there's something going on in the DFW area. I often get No TIS-B and no tower reception on my IFD540/AXP340/MLB100 setup or my Stratux receiver when flying in the area, on my way from Austin to Sherman. I Javen't pinpointed if there is a geographic area where it happens most often. This is why I would prefer to have a dual-band receiver for my IFD setup.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote daveS Quote  Post ReplyReply Direct Link To This Post Posted: 30 Sep 2019 at 6:01pm
Not in my case -- I got similar results (No TIS-B) from Dallas<->Lubbock and Dallas<->Gulf Shores, AL.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote daveS Quote  Post ReplyReply Direct Link To This Post Posted: 15 Oct 2019 at 11:37am
I flew from the North Dallas area to/from Shawnee, OK at 5500'/6500' recently.  The iFD-440's reported no TIS-B traffic for the entire round-trip.  Traffic was being displayed on the IFD-440's, the Lynx NGT-9000, the EX5000 and my iPad (connected via WiFi to the NGT-9000).  Weather was fine and had no warnings or issues.  I sent in my trip to the FAA for an ADS-B check and all came back green.

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.  

Avidyne -- what is the condition that causes the No TIS-B message to display?  Is this perhaps a bug fixed by 10.2.4.1?

I'm taking my plane to the shop next week so any hints would be appreciated.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote AviSteve Quote  Post ReplyReply Direct Link To This Post Posted: 15 Oct 2019 at 2:25pm
Originally posted by daveS daveS wrote:

what is the condition that causes the No TIS-B message to display?  Is this perhaps a bug fixed by 10.2.4.1?
See this post.  Nothing included in 10.2.4.1 that would affect TIS-B.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PA23 Quote  Post ReplyReply Direct Link To This Post Posted: 15 Oct 2019 at 3:38pm
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
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ansond Quote  Post ReplyReply Direct Link To This Post Posted: 15 Oct 2019 at 5:02pm
I am beginning to think this is actually an FAA originated issue... there are several threads in the forum with folks seeing the same thing - lots of "no TIS-B" annunciations recently and without reason. 

I used to never get them... and today, I still seem to get all of the traffic same as before... just with this annunciation. No config changes on my side and everything in my ship seems to operate perfectly otherwise... 

FYI, the FAA recently published that it has "completed" its ADS-B rollout ahead of 2020... so I cannot help but wonder if there have been recent changes to the system that have changed the ADS-B system's triggers/thresholds/configuration/etc... hence these annunciations popping up...

Doug
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Post Options Post Options   Thanks (0) Thanks(0)   Quote daveS Quote  Post ReplyReply Direct Link To This Post Posted: 15 Oct 2019 at 6:50pm
In my case, the NGT-9000 does not have the yellow satellite error or any other error.  Given the positive FAA Ads-B report, I’m also a participating aircraft.  Will the logs detail the airinc-429 data?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PA23 Quote  Post ReplyReply Direct Link To This Post Posted: 16 Oct 2019 at 9:38am
couldn't tell you if the logs include AIRINC-429 data.

But for a point of reference and I think you are aware of it, the FAA ADS-B performance report just lets you know if the FAA hears you properly, it doesn't include any information on what data was transmitted to you, or more specifically to area that you are in.

I've only made a few flights with the IFD440 so I can't comment with any authority on what it is displaying (or what I'm doing right or wrong with it), but I know that I am only sending traffic data to the IFD over AIRINC-429, when I get the plane back from my A&P I'll get the AIRINC-429 disconnected and connect the serial to allow all TIS-B and FIS-B to flow to the IFD.

-Jeff
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Post Options Post Options   Thanks (0) Thanks(0)   Quote daveS Quote  Post ReplyReply Direct Link To This Post Posted: 22 Oct 2019 at 2:48pm
Took my plane into the shop today.  They reached out to Avidyne and provided them logs and performed various tests.  They've acknowledged the 'No TIS-B' message is in error and the fix will be provided in a future update.  No timing for the fix.
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Post Options Post Options   Thanks (1) Thanks(1)   Quote HenryM Quote  Post ReplyReply Direct Link To This Post Posted: 22 Oct 2019 at 3:50pm
See the discussion in the PAPR geoalt thread at http://forums.avidyne.com/papr-geoalt-missing-element-ifd-440-axp-340_topic1868_post22900.html#22900

It has some pretty good clues as to what is happening. AviSteve mentions the following:

Quote
Here's some guidance and specific answers from our resident expert.

First off, just to clarify: TIS-B in this case is shorthand for TIS-B and ADS-R and No TIS-B is only an indication there is a possibility your traffic picture is incomplete.  

All groundstations broadcast a list of the aircraft for which they are currently providing TIS-B/ADS-R targets, if your ICAO doesn't show up in the list for more than a few tens of seconds, you will receive the No TIS-B indication.  Somewhat counter-intuitively, the "No TIS-B" indication has no relationship to the receipt of TIS-B or ADS-R targets.  You could be receiving tons of TIS-B targets while showing the "No TIS-B" indication and you could be receiving zero TIS-B targets and not see the message.  The message is completely driven by whether the IFD has received Service Status messages from the groundstations.

Quote
Another possibility is that there are more messages to be sent from the ADS-B in device to the IFD than there is available bandwidth on the interface.  If the ADS-B device manages the bandwidth by dropping Service Status messages, that would cause the dreaded No TIS-B indication.


Edited by HenryM - 22 Oct 2019 at 3:54pm
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Post Options Post Options   Thanks (1) Thanks(1)   Quote HenryM Quote  Post ReplyReply Direct Link To This Post Posted: 24 Nov 2019 at 7:58am
Just a follow-up, the issue of No-TIS was an FAA bug in the local area that caused the issue described in the blue quoted message above - no service status message was being transmitted but the ground stations. See the thread I linked in the post above. Doug Anson was able to find someone at the FAA to listen and they actually fixed the bug and have put something in place so it doesn't happen again. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PA23 Quote  Post ReplyReply Direct Link To This Post Posted: 24 Nov 2019 at 9:03am
Not doubting what you've suggested, however I can confirm that during yesterday's flight through the NY Class B (West to East) I had the TIS-B indicator pop up once or twice on the screen but I did not have it come up on the transponder (NGT-9000).  Since the transponder is also processing the data I would expect both to show the alert if in fact the ground stations stopped sending ADS-R or TIS-B.

A wacky theory however, seeing that I'm in the NY airspace and ADS-B out will be required in just over a month, is it plausible that there is nobody around me that would have generated an TIS-B target at that time? In addition I and probably many (most?) ADS-B IN  units are dual frequency and listen on both 978 and 1090, ADS-R would not need to be transmitted.  I guess it is plausible but highly doubtful.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote ansond Quote  Post ReplyReply Direct Link To This Post Posted: 24 Nov 2019 at 11:56am
From what I was told, the issue was that the service status message was not being sent out... however, the traffic targets were... so... perhaps the (super awesome...) Lynx transponder can actually "ignore" or compensate that the service status message is not present if it sees targets being delivered.   

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...

Flight yesterday went perfectly around Austin... no TIS-B annuncations... I confirmed that I was seeing the same number of targets between my Skytrax/IFD system and my Stratus2S (dual-bander)... everything seemed to be working perfectly.   Going to go up today and double-check as well. 

Doug


Edited by ansond - 24 Nov 2019 at 11:56am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote daveS Quote  Post ReplyReply Direct Link To This Post Posted: 25 Nov 2019 at 12:20pm
+1 on Avidyne looking into an additional method for suppressing the No TIS-B indicator when it is actually receiving valid traffic data (similar to the NGT-9000).

A week or so ago I flew through the DFW Bravo in the morning and did not see a 'No TIS-B' indicator for the entire route to T82 (west of Austin).  On the return trip, the 'No TIS-B' was on the entire time.  Traffic on all devices (EX5000, NGT-9000, iPad and IFD440's seemed consistent).
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ansond Quote  Post ReplyReply Direct Link To This Post Posted: 25 Nov 2019 at 4:36pm
Yep... yesterday and today, I got a 0% TIS-B client PAPR report after my flights... so I think the FAA must still be working the issue... hopefully they can fix it and stabilize it.   I was out west of KHYI around PINCH... 

Doug


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Post Options Post Options   Thanks (0) Thanks(0)   Quote matthewsjl Quote  Post ReplyReply Direct Link To This Post Posted: 25 Nov 2019 at 9:13pm
Quote suppressing the No TIS-B indicator when it is actually receiving valid traffic data

Hang on.... I don't think that is possible. While the service message may be missing while receiving TIS-B or ADS-R targets there is no way for a unit to determine if the TIS-B or ADS-B targets it is receiving are valid for your specific aircraft.

I have to say that Aspen has the message right IMHO: "TRAFFIC DEGRADED". Use what you have and keep your eyes open more.

"No TIS-B" just seems overtly strong for a display message.

I actually have the problem of the "No TIS-B" message the other way round. I have a GTX-345 providing traffic to an iPad (Garmin Pilot) and to 3 x Aspen screens plus the IFD-540. A few times today (7h of flying) I had the "TRAFFIC DEGRADED" message on the Aspens which mirrored the iPad traffic indicator in Garmin Pilot. The IFD didn't show any "No TIS-B" warning. Now, in my case, I have a feeling it may be something funky in the Avidyne processing of the messages of the RS-232 line but as I'm hooked up in a non-standard way pushing both wx and traffic over the RS-232 line, this may be something I have to live with (trusting the Aspen/iPad display more than the Avidyne).

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Post Options Post Options   Thanks (0) Thanks(0)   Quote daveS Quote  Post ReplyReply Direct Link To This Post Posted: 26 Nov 2019 at 10:00am
I guess my complaint is that the NGT-9000 is showing no errors while the IFD's are showing 'No TIS-B'.  Both show the same traffic -- including TAS.  If Avidyne believes the message is appropriate, I'd much prefer it to be an Alert than I can dismiss or make it much less intrusive.
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Post Options Post Options   Thanks (1) Thanks(1)   Quote PA23 Quote  Post ReplyReply Direct Link To This Post Posted: 26 Nov 2019 at 11:41am
Keep in mind, I have only made 2 flights since I connected the ADS-B out from the transponder to the IFD440 over RS232, previously it was connected via ARINC 429 as it replaced a 430W plus I've only had the unit for about 2 months.

I have seen on the transponder the flag indicating no TIS-B service too (yellow icon lower left) and was receiving a TIS-B target (this was about a month prior to purchasing the IFD440)

(image was taken someplace between EWR and ABE in late September)
The Diamond symbol is a non-directional target which as I understand it is a TIS-B target, an ADS-B target will be an arrow similar to the one used to indicate my position.

I have also received the no TIS-B indicator on the IFD440 but I do not believe the indicator was lit on the transponder at the time.  I really don't know who's at fault, the FAA, L3, Avidyne, or somebody else, even though the traffic reporting is "advisory in nature" it would be nice to be able to rely on the traffic reporting as too many pilots will simply fly with their heads down now.  I think the real concern is the validity of the alert and what triggers it.

Keeping in mind that I'm flying primarily in airspace that will require ADS-B out in just over a month and I have dual 978/1090 in I won't be that dependent on the ground stations for traffic.  Of course you'll still have the aircraft without an electrical system flying around (eg the two gliders I spotted on Long Island doing circles off the departure end of the runway)

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Post Options Post Options   Thanks (0) Thanks(0)   Quote PA23 Quote  Post ReplyReply Direct Link To This Post Posted: 02 Dec 2019 at 1:43pm
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
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ddgates Quote  Post ReplyReply Direct Link To This Post Posted: 02 Dec 2019 at 2:09pm
AviSteve I believe has covered this in other threads...

the "No TIS-B" message is triggered by the aircraft's hex code not being included in the inclusion list of aircraft being detected and serviced by the ground station.  If your TXP pout is reporting a receiver on board, the ground station should include your hex code in the serviced list.  The message does not mean no traffic is being received.  It means no report is being addressed specifically to your aircraft.

That is counterintuitive, but it is what we have been told...




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Post Options Post Options   Thanks (0) Thanks(0)   Quote matthewsjl Quote  Post ReplyReply Direct Link To This Post Posted: 02 Dec 2019 at 5:06pm
But the IFD shoudl match with the transponder if that is the source of the data (unless there is an interface problem where for some reason your ID isn't sent over the interface from the transponder to IFD).

Joh
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Post Options Post Options   Thanks (0) Thanks(0)   Quote daveS Quote  Post ReplyReply Direct Link To This Post Posted: 03 Dec 2019 at 3:52pm
Originally posted by ddgates ddgates wrote:

AviSteve I believe has covered this in other threads...

the "No TIS-B" message is triggered by the aircraft's hex code not being included in the inclusion list of aircraft being detected and serviced by the ground station.  If your TXP pout is reporting a receiver on board, the ground station should include your hex code in the serviced list.  The message does not mean no traffic is being received.  It means no report is being addressed specifically to your aircraft.

That is counterintuitive, but it is what we have been told...
FWIW - As I've been posting a few times in this thread thought I'd mention I flew yesterday in the Dallas area out to Paris, TX (~70 nm) and didn't see the 'No TIS-B' message for the 1.3 hr roundtrip flight.

Steve -- I can understand displaying the message when the IFD is acting as the head for a remote ADS-B transponder but when the IFD is just displaying data received by an NGT-9000 or GTX-345 (which have their own display and indicators), why give the option to suppress the message?
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Post Options Post Options   Thanks (1) Thanks(1)   Quote AviSteve Quote  Post ReplyReply Direct Link To This Post Posted: 04 Dec 2019 at 1:04pm
Originally posted by daveS daveS wrote:

Steve -- I can understand displaying the message when the IFD is acting as the head for a remote ADS-B transponder but when the IFD is just displaying data received by an NGT-9000 or GTX-345 (which have their own display and indicators), why give the option to suppress the message?
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%.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote daveS Quote  Post ReplyReply Direct Link To This Post Posted: 04 Dec 2019 at 2:14pm
Originally posted by AviSteve AviSteve wrote:

Originally posted by daveS daveS wrote:

Steve -- I can understand displaying the message when the IFD is acting as the head for a remote ADS-B transponder but when the IFD is just displaying data received by an NGT-9000 or GTX-345 (which have their own display and indicators), why give the option to suppress the message?
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%.
Yup.  I guess my point is that in my case the device actually receiving the ADS-B data, an NGT-9000, does have indicators, warnings and messages.  I do expect that this would be the definitive source for any error conditions.  The IFD is a receiver of data from the NGT-9000 so I would not actually be expecting it to be doing an integrity check against the raw datastream that is broadcast from a ground station to a different device.  That's why I would suggest the IFD make these types of messages either optional and/or just logged.

In the end though, the perplexing item from this situation is that the NGT-9000 which directly receives the data does not detect an error condition while the IFD does  (sometimes).
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