same database different approach indication?

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   Anyone know what conditions would cause a different approach indication on a dual-IFD installation?
I have a IFD540/440 pair. The IFD540 has aviOS 10.2.4 and the IFD440 has 10.2.6. Both have the same (current) navdata coverage and cycle loaded.

Yesterday I did an RNP approach that has only LNAV minimums..... also 2D. On the IFD540 this was shown as GPS LNAV (upper right corner). On the IFD440 this was shown as GPS LNAV+V. Why/how the difference? Is this due to some difference between the OS releases? 

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chflyer Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 24 Jan 2013 Location: LSZK Status: Offline Points: 1034	Post Options Post Reply Quote chflyer Report Post Thanks(0) Quote Reply Topic: same database different approach indication? Posted: 06 Sep 2023 at 5:40am
	Anyone know what conditions would cause a different approach indication on a dual-IFD installation? I have a IFD540/440 pair. The IFD540 has aviOS 10.2.4 and the IFD440 has 10.2.6. Both have the same (current) navdata coverage and cycle loaded. Yesterday I did an RNP approach that has only LNAV minimums..... also 2D. On the IFD540 this was shown as GPS LNAV (upper right corner). On the IFD440 this was shown as GPS LNAV+V. Why/how the difference? Is this due to some difference between the OS releases?
	Vince

AviSteve Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 12 Feb 2018 Location: Melbourne, FL Status: Offline Points: 2244	Post Options Post Reply Quote AviSteve Report Post Thanks(0) Quote Reply Posted: 06 Sep 2023 at 3:46pm
	First, I would not recommend having different software versions on your IFDs. Nevertheless, it's unlikely that the different software versions were the cause of the discrepancy. One possibility is that your 440 has the Advisory Glideslope setting ON but the 540 has it OFF. Another possibility is that the 540 GPS just didn't have the vertical accuracy to do +V while the 440 did.
	Steve Lindsley Avidyne Engineering

chflyer Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 24 Jan 2013 Location: LSZK Status: Offline Points: 1034	Post Options Post Reply Quote chflyer Report Post Thanks(0) Quote Reply Posted: 10 Sep 2023 at 8:25am
	Duh.... yeh, you hit it on the head Steve.... Advisory Glideslope settings as mentioned. Regarding different software versions, I understand the position but sometimes that's the result of Avidyne's own behaviour. I got my IFD440 back from repair with a different AviOS version after spending $2'500 for warranty repair ("LCD screen delamination" above the Avidyne Label in normal operation but not in maintenance mode ..... how Avidyne can claim that I caused this is a mystery to me, it seems anything related to the screen is automatically treated as customer caused). The unit left Avidyne back to me the day before 10.3 was released, so I was looking at an additional $500 to update both units to the same release (10.3).... too much all at once.
	Vince