IFD 5 Series & IFD 4 Series Touch Screen GPS/NAV/COM - Visual Approaches

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Visual Approaches - How to intercept final

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=2516
Printed Date: 01 May 2024 at 9:18am
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com

Topic: Visual Approaches - How to intercept final

Posted By: guenter_ms
Subject: Visual Approaches - How to intercept final
Date Posted: 03 May 2023 at 3:14am

Hi,

I'm not sure about the best practice to intercept the final on a visual approach on my 540/440 combo.

Assuming the last waypoint on my FPL is a VFR only airport and the waypoint is active and autopilot is in GPSS mode. Loading (and not activating) the Visual Approach to the active runway appends two new waypoints to the FPL: RW09 (final track) and repeats the destination airport marked as "destination". So far so good.

Now: How to intercept the final?

My questions:

How to find the TOD at which altitude according to the configured final length (setup VA)?
How to get a waypoint there for easy navigation and autopilot setup, altitude constraint included?
How to activate the visual approach *automatically* when passing the last waypoint before the /Visual Approach/ gap in FPL (the final track is next leg and magenta/white)?
What will be the GPSS track output = input to autopilot (e.g. s-tex 55x) when visual approach is active (I tried a lot with the simulator app but didn't get a clear answer to that question)?

As an FI I'm also familiar with the GTN 750 form Garmin. When loading an visual approach, a (configurable) 3 nm waypoint with altitude constraint according to the configured glide path is automatically included into the FPL, followed by the final track to the RWY. That is awesome!

Is there any setup I missed to get that behavior as well?

Thanks so much for answers to my questions. Maybe I didn't understood the correct how to's. I love the avidyne's but this point is really unclear for me.

Take care!

Replies:

Posted By: vas4avidyne
Date Posted: 04 May 2023 at 12:59am

Unlike with an instrument approach where one can connect the rest of the flight plan to the approach, I haven't found any way to connect the visual approach to the rest of the flight plan. It seems to exist in isolation and only becomes active when one selects "Activate Visual". I haven't found a way to automatically activate the visual approach even if one intercepts the final approach path.

I am not sure what the protocol level output is to the AP when it is active but for all intents and purposes, the AP tracks it just like it would an RNAV approach with vertical guidance (e.g. LPV).

Vas

Posted By: Ibraham
Date Posted: 04 May 2023 at 3:46pm

Treat it like being vectored by ATC to intercept an ILS or final approach course on an RNAV approach.

Autopilot in heading mode with NAV (or APR) armed (blue), it will fly the selected heading then intercepts the final approach course (visual approach course in this case) and automatically activates NAV.

Posted By: guenter_ms
Date Posted: 11 May 2023 at 3:57am

@avidyne:

Can you comment? The answers to the 4 questions above seems to be:

1. not possible

2. not possible

3. not possible

4. unclear

Thats not really satisfying. So I demand this

FEATURE REQUEST

When loading an visual approach, an additional waypoint is inserted at 3nm (customizable, e.g. from defined „final length") from RWY with an altitude constraint computed by distance form RWY and glidepath. This will solve all questions and makes it possible to append the VA to the plan, allowing to see all timings and distances in advance. That would be a great kick. Why should Garmin be so much better at this easy point?

By the way: Loading a VTF approach does this since day one: Automatic waypoint to FAF is inserted. Why not on a VA?

Best Guenter

(Any one supporting this?)

Posted By: paulr
Date Posted: 11 May 2023 at 11:33am

I like that idea, Guenter.

Posted By: guenter_ms
Date Posted: 24 Jul 2023 at 1:47am

@avidyne: please comment. Thank you.

Posted By: MysticCobra
Date Posted: 24 Jul 2023 at 8:17am

guenter_ms wrote:

FEATURE REQUEST

Guenter, have you submitted this via Avidyne's "official" feature request form?

Avidyne forum post about the process: http://www.avidynelive.com/submit-your-suggestions_topic2483.html" rel="nofollow - http://www.avidynelive.com/submit-your-suggestions_topic2483.html

Direct link to the form: https://www.avidyne.com/contact-us-2/" rel="nofollow - https://www.avidyne.com/contact-us-2/

Posted By: AviSteve
Date Posted: 24 Jul 2023 at 9:45am

Visual approaches are preceded by a discontinuity just like vectors-to-final for an instrument approach. The difference is that an instrument approach has a FAF (from the database) whereas a visual approach does not (because a visual approach doesn't come from the database).

We tried various implementations of visual approaches during development, including the addition of a waypoint at "final length", but eventually settled on the current implementation because we thought that it worked best.

I've created a feature request in our database for consideration.

-------------
Steve Lindsley
Avidyne Engineering

Posted By: guenter_ms
Date Posted: 24 Jul 2023 at 10:48am

Thank you Steve,

as an FI I'm flying Avidyne and Garmin units and can strongly confirm the advantage of that feature.

I understood you copied the request, so I don't need to do that again.

Best

Guenter