IFD 5 Series & IFD 4 Series Touch Screen GPS/NAV/COM - Hold patterns and other NEXT DTK issues

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Hold patterns and other NEXT DTK issues

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=962
Printed Date: 14 May 2024 at 1:11pm
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com

Topic: Hold patterns and other NEXT DTK issues

Posted By: cavu
Subject: Hold patterns and other NEXT DTK issues
Date Posted: 10 Feb 2016 at 1:43pm

I noticed when flying a hold, let's say a direct entry to hold south of a fix on the 180 radial, left hand turns.

I have DTK on the upper data block and Next DTK on the Right data block.

As I approach the hold, the inbound leg to the fix is magenta and the DTK is showing 360. The turn to the outbound leg is a bar-pole color but the Next DTK, and the DTK for that matter, shows 360 and never changes during the hold.

Is this normal, by design, behavior? if so its a little confusing. Can you please explain the logic/intent behind it? I was under the impression that the next leg (bar-pole) track would appear in the Next DTK field. This would be particularly helpful when making other than direct entries that are not on cardinal headings.

Replies:

Posted By: AviJake
Date Posted: 10 Feb 2016 at 2:39pm

"DTK" always shows the desired track for the active leg and "Next DTK" always shows the desired track of the next leg. Note that a hold is considered a single leg, not four legs. For a hold, the DTK is always the inbound course (i.e. it does not vary as you fly the hold). We decided to do it that way so that deviations would match the operation of a traditional CDI.

We ran a simulation of your scenario here just to be sure it was working per design (and it is). In that scenario, when the leg to the hold fix is active, 360 is displayed for both DTK and Next DTK. When you cross the hold fix on entry, the DTK is 360 and the Next DTK will be the desired track of the next leg (i.e. the leg after the hold). In our simulation, that just happened to be 133°. If there is no next leg, Next DTK will show dashes.

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Steve Jacobson
sjacobson@avidyne.com

Posted By: cavu
Date Posted: 10 Feb 2016 at 8:02pm

Right, I forgot to mention that about the next leg past the hold. That might be some of the confusion. Why not show dashes in the next DTK until the EXIT HOLD lnk is pressed, then show the Next DTK.

The bar-pole coloring scheme gives the impression that the hold is made up of 4 legs as you put it.

As for keeping the CDI indication the same as the traditional CDI certainly has some merit but the actual deflection is not all that useful. First of all the next DTK readout does not drive the CDI needle, right? So the "proper" heading in the next DTK would not affect the needle. When entering the turns in the hold the CDI indication could more meaningfully switch to the inbound or outbound track providing the same benefit that the traditional CDI indication provides inbound plus be more meaningful outbound. Maybe, a different color of the bar-pole? It seems like a disconnect. The magenta bar-pole in my understanding looking at the display is the next active leg, but the next DTK does not correspond to it.

Just some alternative thoughts. Thanks for a great product.