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

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FPM vs ANGLE for descent

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=2510
Printed Date: 19 May 2024 at 3:22am
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com

Topic: FPM vs ANGLE for descent

Posted By: oskrypuch
Subject: FPM vs ANGLE for descent
Date Posted: 25 Apr 2023 at 9:33am

Noticed this option with 10.3, perhaps to support the new VNav, which unfortunately I can't use as it is disabled for non-550 untis.

I normally set a FPM target to chime the TOD gong. I'm wondering if using ANGLE might be better, or perhaps it won't really work, as I don't have VNav available (or set). I presume that both methods take into account the instantaneous winds by using GS, and the difference is just a bit of arithmetic.

Anyone using 10.3 for a while, what do you do?

* Orest

Replies:

Posted By: Sanjiv
Date Posted: 02 May 2023 at 8:29pm

I'll test mine this week. Enroute VNAV enabled in setup menu (not settings)? From user manual it seems that FPM is eventually converted into angle for guidance. (page 6-38)

"When a target vertical speed is specified, the IFD will compute the TOD point using current groundspeed and the desired descent rate. However, when the aircraft reaches the TOD point and enroute VNAV is allowed, the IFD will compute the angle required to reach the desired altitude, then commence with enroute VNAV using that angle. "

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PA28-236 @N14

Posted By: Gring
Date Posted: 03 May 2023 at 7:28am

Orest,

After a bit of playing, I went back to a FPM value. This allows me to set the autopilot, or hand fly with a known target value for vertical speed.

Posted By: MysticCobra
Date Posted: 03 May 2023 at 11:50pm

Does it really matter, if you're using the Boeing Banana as your guidance?? ;-)

Posted By: oskrypuch
Date Posted: 06 May 2023 at 9:39pm

The Banana rules!

* Orest