IFD 5 Series & IFD 4 Series Touch Screen GPS/NAV/COM - Loss of approach tracking & odd alert

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Loss of approach tracking & odd alert

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=1033
Printed Date: 22 Dec 2024 at 8:53am
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com

Topic: Loss of approach tracking & odd alert

Posted By: bcool
Subject: Loss of approach tracking & odd alert
Date Posted: 05 Apr 2016 at 7:28am

I'm starting to learn the nuances of my new IFD540 and ran into a couple of strange things last night.

I was flying the RNAV 18 LNAV approach into KSET using my STEC55X autopilot. I was proceeding direct to LUNGY (the IAF) and the 55X was in NAV/GPSS mode. Upon reaching LUNGY, the 540 sequenced to a teardrop reversal leg (as charted) and the 55X began the teardrop turn.

However, when it got time to make the turn back inbound, it just kept flying straight ahead. To get things back on track I switched the 55X into heading mode and made the turn using the heading bug. When I got back to the GPS course I switched back to NAV/GPSS and things were fine from then on.

Anyone else experience this?

Also, another oddity...as I was inbound to the FAF at the charted altitude of 2,300', the 540 gave me a yellow warning that my altitude was too low. Why would that be, if I was right at the altitude shown on the approach plate? The only thing I could figure was that the pressure altitude being reported by my transponder was 200' lower than my actual altitude due to the density altitude - could this have triggered the warning?