pecanflyboy
Well Known Member
November 2020 - G3X (non-touch), GSU73, GTN650Xi.
After updating my G3X to software load 12.10, I begain receiving the following message on my GTN650Xi: "VNAV Unavaialble:Barometric altitude lost." After several back and forths with Garmin, the pinouts were check, and all configurations were checked. Don't be tempted to just set the GTN to VCALC so the message goes away. In VCALC you lose VNAV and transition to approach. This is a very valuable tool for approach workload and safety. We then dove into the GTN diagnostics.
GTN Diagnostics page - Main Data Inputs: Barometric altitude was blank. It should show barometric altitude.
GTN Diagnotics page - ARINC Inputs: I was directed to select ARINC 429 port 1 input. If working correctly, you will see a live data stream. I paused the stream, and was directed to look for label 204. This label is the barometric altitude data. If I looked deep enough, I would find a sporatic label 204. Sometimes I could not find it at all. This began to point towards the GTN not seeing the GSU73 barometic data.
As of right now, the G3X engineers have found a bug in the 12.10 software, with the label 204 data on the G3X side. Hopefully, a new software release will be coming soon.
After updating my G3X to software load 12.10, I begain receiving the following message on my GTN650Xi: "VNAV Unavaialble:Barometric altitude lost." After several back and forths with Garmin, the pinouts were check, and all configurations were checked. Don't be tempted to just set the GTN to VCALC so the message goes away. In VCALC you lose VNAV and transition to approach. This is a very valuable tool for approach workload and safety. We then dove into the GTN diagnostics.
GTN Diagnostics page - Main Data Inputs: Barometric altitude was blank. It should show barometric altitude.
GTN Diagnotics page - ARINC Inputs: I was directed to select ARINC 429 port 1 input. If working correctly, you will see a live data stream. I paused the stream, and was directed to look for label 204. This label is the barometric altitude data. If I looked deep enough, I would find a sporatic label 204. Sometimes I could not find it at all. This began to point towards the GTN not seeing the GSU73 barometic data.
As of right now, the G3X engineers have found a bug in the 12.10 software, with the label 204 data on the G3X side. Hopefully, a new software release will be coming soon.