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VSR on the Final Segment

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=1961
Printed Date: 13 Jul 2020 at 5:41pm
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com


Topic: VSR on the Final Segment
Posted By: cavu
Subject: VSR on the Final Segment
Date Posted: 04 Apr 2020 at 3:43pm
I have noticed that the VSR data block goes blank during the final segment.

If I'm flying an RNAV, precision or non-precision approach, it would be very handy to have the computed VSR to the touchdown point calculated.  I can not alter the MAP entry in the flight plan to enter an altitude so the VSR just goes blank.  The IFD knows the touchdown altitude, my ground speed, and my current altitude.  Could it (and shouldn't it) calculate what the VSR should be?  A nice cross check of what type of descent I will need to stay on glide slope or from VDP or MDA.



Replies:
Posted By: AviSteve
Date Posted: 06 Apr 2020 at 9:19am
Way back when, we decided it would be best to not show the altitude constraint at the MAP or allow one to be entered.  I vaguely remember it just being a safety and liability concern, but don't remember any of the arguments.  It's probably worth revisiting at some point.


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Steve Lindsley
Avidyne Engineering


Posted By: cavu
Date Posted: 06 Apr 2020 at 9:44am
Hi Steve,

Hope all is well.

Seems to me you could provide a VSR value for the final segment without having to enter anything.  All the parameters are known. Present altitude, distance from touchdown, ground speed and touch down height.  This would provide better information than the VSR block that's included on some approach charts and based on a few ground speeds.

Thoughts?

Course turning on the altitude on the final waypoint of the approach might be easier.

Its not being forced on anyone, those who don't want it can simply not enter it and probably won't be monitoring VSR anyway.


Posted By: AviSteve
Date Posted: 06 Apr 2020 at 10:28am
VSR works on altitude constraints, so if one were associated with the leg it would all work itself out.  Yeah, we could make it generate VSR for the MAP without entering a constraint, but that would be more special case stuff.  The fewer special cases, the better.  As I suggested, it's something we can revisit.

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Steve Lindsley
Avidyne Engineering


Posted By: AZ Flyer
Date Posted: 06 Apr 2020 at 10:55am
Originally posted by cavu cavu wrote:

I have noticed that the VSR data block goes blank during the final segment.

If I'm flying an RNAV, precision or non-precision approach, it would be very handy to have the computed VSR to the touchdown point calculated.  I can not alter the MAP entry in the flight plan to enter an altitude so the VSR just goes blank.  The IFD knows the touchdown altitude, my ground speed, and my current altitude.  Could it (and shouldn't it) calculate what the VSR should be?  A nice cross check of what type of descent I will need to stay on glide slope or from VDP or MDA.

I end up referring to Foreflight's Descent to Dest data block at that point, which is VSR to destination elevation and therefore not the same as VSR to MAP but better than nothing.  I find it quite annoying that there is no way to even manually enter a MAP at the destination airport in order to continue to see the VSR in the data block.  It makes no sense at all that this would be a liability concern because everything we do with these boxes involves an element of personal decision making and therefore potential liability, if such exists at all.

At least give us the same option as with other waypoints to manually enter an altitude and a distance from the waypoint for that altitude.  That way, it is our decision alone and not something Avidyne is having to determine and therefore assume responsibility for.


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Stan



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