IFD 5 Series & IFD 4 Series Touch Screen GPS/NAV/COM

GPS Loss and Terrain Warning

Printed From: Avidyne
Category: Avidyne General
Forum Name: IFD 5 Series & IFD 4 Series Touch Screen GPS/NAV/COM
Forum Description: Topics on Avidyne's IFD 5 Series and IFD 4 Series Touch Screen GPS/NAV/COM
URL: http://forums.avidyne.com/forum_posts.asp?TID=534
Printed Date: 18 May 2024 at 2:23pm
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com

Topic: GPS Loss and Terrain Warning

Posted By: teeth6
Subject: GPS Loss and Terrain Warning
Date Posted: 01 Jan 2015 at 1:16pm

I had no problem on my long trip down to the Bahamas but coming back to the US today I had many with the top 540. I am not sure if this is related to the GPS signal loss that someone else spoke of but I had many, many GPS signal losses with some lasting 5 min. Each one was followed by a "Terrain Ahead, Pull up Warning" even though I was at 8000 ft over the ocean :). At the same time ATC told me they lost my transponder code and asked me to recycle. I noticed that at these times, the transponder said ADSB signal lost but it came back on when the GPS warning disappeared. The red alert for the terrain stayed on the whole flight. I cycled the top 540 to see if that would correct the issue but after it rebooted, the GPS signal loss issue started again along with the "terrain warning, pull up" issue. Any thoughts. I still have a flight home from Florida in front of me and was hoping there was something I could do to correct this.

Replies:

Posted By: AviJake
Date Posted: 01 Jan 2015 at 1:27pm

You've experienced the same GPS loss that several folks have seen on their units. We believe we've addressed those as part of Rel 10.0.3.0 that is going through final testing now.

As for the terrain alerts, that is a natural, albeit undesired, behavior of the system recovering from a GPS loss and momentarily thinking it's got a low GPS altitude. The root cause of that (GPS loss) should go away in Rel 10.0.3.0 but we've also made a change in Rel 10.1 code that suppresses that terrain alert in the event of a GPS recovery.

I definitely wouldn't expect to see the red terrain warning message stay on for the entire flight however.

If you can, send me/us your datalogs and we'll take a quick peek at them to see if anything interesting shows up. (sjacobson@avidyne.com and I'll make sure the logs get passed along to others as well).

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Steve Jacobson
sjacobson@avidyne.com

Posted By: teeth6
Date Posted: 01 Jan 2015 at 9:23pm

Steve,

I had some time to download the system log files when I stopped for the night enroute. Please let me know if you also need the other log files (engine, etc). I emailed the log file to you. The red terrain warning definitely did stay on for the whole flight and even came back on after I did a restart of the top unit but I figured that was cross feeding from the bottom unit which also displayed the red warning. Do you have any idea what triggers this GPS signal loss ...ie, is there some combination of actions I can avoid to not trigger it? It is strange it happened repeatedly on my top unit but not at all on the bottom unit. Also, weird it had not happened on the top unit thru many hours of use until this trip. Let me know if the log files give an hints or if you need other logs as well.

Posted By: AviJake
Date Posted: 03 Jan 2015 at 8:10am

Looking. Will report back any findings.

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Steve Jacobson
sjacobson@avidyne.com

Posted By: teeth6
Date Posted: 03 Jan 2015 at 8:26am

Thank you will email you photos of the display also

Posted By: AviJake
Date Posted: 05 Jan 2015 at 4:18pm

Got the datalogs and pix and we see something unusual with respect to the terrain alerts but we need more information.

Specifically, we need:

1. Date of the occurrence.
2. Event logs from both IFDs.
3. Flight logs from both IFDs.
4. System log from the other IFD.

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Steve Jacobson
sjacobson@avidyne.com

Posted By: teeth6
Date Posted: 05 Jan 2015 at 4:54pm

Date of occurence is January 1, 2015. I will get the other logs asap.