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Garmin GTX345, Dynon D180, Alt Baro fault in ADSB
- Thread starter Shadetree
- Start date
Hello Shadetree,
Without seeing the report it is hard to know if it is failing because there is no altitude being reported or failing because it fails a reasonableness check when compared to GPS altitude.
If you are able to operate in ALT mode, it is probably receiving altitude data, so perhaps it appears to the ground stations like this data is in error. You don't say if you have the built-in WAAS GPS module inside the GTX345, but we are guessing you do.
Your GTX 345 will display the pressure altitude on the front panel, so you can certainly see if the transponder is receiving altitude data from your D180 device.
As you know, the GTX 345 supports many different altitude input formats including Shadin, Sandia, Icarus, ACK, and Transcal, so you should be able to select something that is compatible.
Probably best to email us if you want to work this issue in more detail and share some/all of your ADS-B Out report.
Thanks,
Steve
Jetguy
Well Known Member
Here is another post where the D180 was connected to the Free Flight ADSB unit and the output of the altitude encoder affected what the FAA was seeing and had to be reset to a different setting. May not even apply to the 345 but it is something to think about. Maybe the G3x guys will have some insight if this would effect their 345. Im considering this same setup as Wade using a 345 and a D180 of which there are about 150 D180s installed in RV12s, Im sure others will be watching so please post the results of the problem. Thanks 
Here is another post where the D180 was connected to the Free Flight ADSB unit and the output of the altitude encoder affected what the FAA was seeing and had to be reset to a different setting. May not even apply to the 345 but it is something to think about. Maybe the G3x guys will have some insight if this would effect their 345. Im considering this same setup as Wade using a 345 and a D180 of which there are about 150 D180s installed in RV12s, Im sure others will be watching so please post the results of the problem. Thanks
I will be sure to post my findings.
It could be a while. I am out of town for a few days.
I just wanted to point out that Shadetree's ADS-B report doesn't say his baro altitude output is failed, it just says it is missing 5.27% of the time.
This probably means that it is properly connected and configured, but for some reason the data is slightly intermittent, but just guessing at this point.
Thanks,
Steve
This probably means that it is properly connected and configured, but for some reason the data is slightly intermittent, but just guessing at this point.
Thanks,
Steve
G3expert has been a huge help trying to sort out my issues. The Garmin GXT is showing the right altitude, it is configured properly, but would appear that the Dynon D180 is not reporting altitude properly. Dynon says it could be wiring or connectors, or the Dynon unit itself. That is where I am today. The cable was ordered already made up professionally so I don't think it is wiring related. I guess I will see if Dynon can tell me if there is a way to check the unit to see if it is not working properly. Stay tuned.
If it's displayed on the GTX345, I don't see how the Dynon D180 could be outputting it in such a way that the transponder would show it on the display, but would not send it out over ADS-B. Maybe the Garmin guys know and can help point us somewhere.
Have you had a 91.413 test done on this install to make sure the power output is sufficient? We've had quite a few experiences lately with bad connections on transponders that cause low output power, and different data drops out a different times when this happens, which is why the FAA requires a transponder test on any new transponder install.
--Ian @ Dynon
Have you had a 91.413 test done on this install to make sure the power output is sufficient? We've had quite a few experiences lately with bad connections on transponders that cause low output power, and different data drops out a different times when this happens, which is why the FAA requires a transponder test on any new transponder install.
--Ian @ Dynon
We contacted the FAA and requested a detailed track log of all parameters for this aircraft. Note that we are unsure of the accuracy of this log, but it probably provides useful information.
As shown in the compliance report and confirmed in the detailed track log, the only missing elements in the output from this transponder are pressure altitude, so a weak output seems very unlikely. For example, there is no drop-out of the GPS data supplied by the GPS receiver module internal to the GTX 345.
As Shadetree mentioned, the GTX 345 is receiving pressure altitude from the D180 and it appears to be correct and always passes the Kinematics checks.
Unfortunately, the supplied pressure altitude data appears to drop out 5% of the time, which not only shows up to the ground stations as missing data in the squitter, but this missing data also affects the Navigation Integrity Category (NIC) which is the calculated integrity containment radius around an aircraft's reported position. The NIC drops to zero and stays there when the pressure altitude supplied to the transponder is not continuous and reliable.
The same D180 was previously being used successfully with a GTX 327, but since that transponder only responds to interrogations and does not continuously squitter like the GTX 345 ADS-B Out transponder, this condition, if present, went undetected.
Just to be clear, we have no idea of the cause and this might be some kind of installation issue. If it cannot be solved, we have the option of installing the small pressure sensor option to the back of the GTX 345 and removing the link to the D180.
Thanks,
Steve
As shown in the compliance report and confirmed in the detailed track log, the only missing elements in the output from this transponder are pressure altitude, so a weak output seems very unlikely. For example, there is no drop-out of the GPS data supplied by the GPS receiver module internal to the GTX 345.
As Shadetree mentioned, the GTX 345 is receiving pressure altitude from the D180 and it appears to be correct and always passes the Kinematics checks.
Unfortunately, the supplied pressure altitude data appears to drop out 5% of the time, which not only shows up to the ground stations as missing data in the squitter, but this missing data also affects the Navigation Integrity Category (NIC) which is the calculated integrity containment radius around an aircraft's reported position. The NIC drops to zero and stays there when the pressure altitude supplied to the transponder is not continuous and reliable.
The same D180 was previously being used successfully with a GTX 327, but since that transponder only responds to interrogations and does not continuously squitter like the GTX 345 ADS-B Out transponder, this condition, if present, went undetected.
Just to be clear, we have no idea of the cause and this might be some kind of installation issue. If it cannot be solved, we have the option of installing the small pressure sensor option to the back of the GTX 345 and removing the link to the D180.
Thanks,
Steve
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Did this issue get resolved?
I'm in the process of installing a GTX 345 and i'm planning to use the ICARUS altitude encoder from my AFS 4500 (Pin 13).
What was the resolution to gain compliance?
Thank you,
I'm in the process of installing a GTX 345 and i'm planning to use the ICARUS altitude encoder from my AFS 4500 (Pin 13).
What was the resolution to gain compliance?
Thank you,
MartySantic
Well Known Member
Resolved yet? I have been seeing similar with the D-180, GTX327 and Navworx ADS600-EXP. After requesting the detailed dataset from the FAA, the BaroAlt will drop to zero or a negative altitude periodically. About 6 times during a 45 minute flight.
Here's my update:
I replaced the GTX 327 in my RV-8 with the GTX 345. I used the Garmin GNS 430 W for the GPS. The AFS 4500 ICARUS altitude encoder is working well with this combination. I've obtained a couple of FAA reports and have passed each time with no identified issues.
Even though I didn't replace my encoder/altimeter, I had the transponder checked and certified by a local shop (in accordance with CFR 91.413). They provided me a sticker for my logbook.
Not yet. Supposed to get it in the shop within a week.
I, too, have a Dynon D-100, HS-34, GNS430W, GTX327. I've purchased a GTX345 but not installed yet. I'll be most interested to hear how this resolves.
LG
RVG8tor
Well Known Member
Connections
I am about to replace my GTX 327 with the GTX 345, I am working on the pin out now. I also have the 430W and D-180
The Dynon out put altitude to the 327 and the 430W via pin 13 from the DB 25 connector. As fare as I can tell there was never a connection between the 430W and the GTX 327.
Since the 430W is getting altitude information from the D-180 and the 430W has a RS232 connection to the GTX-345, is the altitude wire that used to go to the 327 still needed?
Thanks for the help in advance.
Cheers
I am about to replace my GTX 327 with the GTX 345, I am working on the pin out now. I also have the 430W and D-180
The Dynon out put altitude to the 327 and the 430W via pin 13 from the DB 25 connector. As fare as I can tell there was never a connection between the 430W and the GTX 327.
Since the 430W is getting altitude information from the D-180 and the 430W has a RS232 connection to the GTX-345, is the altitude wire that used to go to the 327 still needed?
Thanks for the help in advance.
Cheers
krhea
Well Known Member
Baro. Fault in adsb
I have had two different instances where the baro altitude stopped for a second during a 1 + hour flight. Have an Iefis explorer feeding a trig tt21 transponder on the can buss. FAA called and sent me the files but I haven' taken the time to look at the IEFIS data. It records. Parameters every second so I should have the info, I can't tell from the google earth files where the baro. supposedly stopped. I guess I'll tackle that after the Holidays.
Keith Rhea
2017 dues paid.
I have had two different instances where the baro altitude stopped for a second during a 1 + hour flight. Have an Iefis explorer feeding a trig tt21 transponder on the can buss. FAA called and sent me the files but I haven' taken the time to look at the IEFIS data. It records. Parameters every second so I should have the info, I can't tell from the google earth files where the baro. supposedly stopped. I guess I'll tackle that after the Holidays.
Keith Rhea
2017 dues paid.
Hello Mike,
I sent you an email from G3Xpert with more information, but here is the short summary.
You will need two serial connections to the GTX 345.
The first is the ADS-B traffic/weather connection between the GNS 430W and the GTX 345. This is bi-directional and not only provides traffic/weather to the 430W, but the 430W provides ADS-B position data to the GTX 345 over this single serial port, so you don?t need a separate, dedicated ADS-B+ port from the 430W to the transponder like needed on other transponders.
The second is the serial port that provides pressure altitude to the transponder. For our G5, we set the G5 serial port to ENCODER and the GTX 345 serial port to ?ALT FMT 3 25 FT?.
Not sure which of the GTX 345 serial port formats you will need for your D180, but you could try the same one we use with the G5 to start. The documentation I provided from the GTX 345 manual shows all the serial port configuration options for connecting a pressure altitude source.
Let us know if you have more questions.
Thanks,
Steve
Walt
Well Known Member
Bob is correct, the TT21 is a class 2 unit and not approved in the USA for ADS-B out, the TT22 is the class 1 version which should be used.
I'm not sure if FAA will be able to tell the difference but come 2020 the folks that do your transponder cert will likely notice the lower power output.
