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IFD 100 VSR

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teeth6 View Drop Down
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    Posted: 09 Sep 2017 at 9:51pm
I notice that the VSR on the IFD 100 does not agree with that on my 540s despite the fact the altitude and distance from the fix is exactly the same on both. Is this a known bug with the IFD 100?
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DavidBunin View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DavidBunin Quote  Post ReplyReply Direct Link To This Post Posted: 10 Sep 2017 at 11:28am
How far off are they?  Is your panel-mounted IFD connected to a barometric altimeter?  Is the IFD100 slaved to the panel mount for GPS data?

Also, are they taking you to the same place?  My IFD540 gives me VSR data to a point a thousand feet above and five miles short of the navigation waypoint.
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teeth6 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote teeth6 Quote  Post ReplyReply Direct Link To This Post Posted: 11 Sep 2017 at 9:39am
They are not far off (maybe 30 feet or so) but I would assume they should be exactly the same.  When I enter the parameters for the crossing altitude into the IFD 100 is goes directly into the IFD 540 so the setup is exactly the same.  They are both using the GPS altitude supplied by the 540 I would assume.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DavidBunin Quote  Post ReplyReply Direct Link To This Post Posted: 11 Sep 2017 at 12:13pm
If it's that close, I would say just live with it.  I target -500fpm when I fly, and if I see a computed VSR anywhere between -400 and -600 I consider that a successful on-target descent.

Groundspeed is always changing during the descent, due to changing winds and any aircraft drag curve parameters that vary with density altitude.  As groundspeed varies, the necessary descent rate will also change.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote AviSimpson Quote  Post ReplyReply Direct Link To This Post Posted: 11 Sep 2017 at 1:37pm
Originally posted by teeth6 teeth6 wrote:

They are not far off (maybe 30 feet or so) but I would assume they should be exactly the same.  When I enter the parameters for the crossing altitude into the IFD 100 is goes directly into the IFD 540 so the setup is exactly the same.  They are both using the GPS altitude supplied by the 540 I would assume.

Is the VSR the same on both IFD540s? Are you connected to one and looking at another possibly?
Simpson Bennett
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teeth6 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote teeth6 Quote  Post ReplyReply Direct Link To This Post Posted: 12 Sep 2017 at 7:29am
Simpson,  I have the VSR data block only setup on 1 of my 540s so I'm not sure if it would be the same on both but I assume it would, as the crossing altitude restriction is the same on both.  Yesterday when I flew, the  VSR difference between the IFD 100 and the 540 was about 60 feet.  As David said, I can certainly live with it, but I was just wondering how or why they would be different.  I assume the IFD 100 is simply displaying the info it gets from the 540 and is not actually calculating the VSR on it own, correct? Perhaps, it is the short time lag it takes the info to get from the 540 to the IFD 100?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AviSimpson Quote  Post ReplyReply Direct Link To This Post Posted: 12 Sep 2017 at 9:49am
Correct, the IFD100 displays whatever the IFD540 sends it. It's possible that there is a lag. I haven't noticed it but I also haven't been looking. I will take a look.
Simpson Bennett
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teeth6 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote teeth6 Quote  Post ReplyReply Direct Link To This Post Posted: 13 Sep 2017 at 6:46am
Thanks.  I'd be interested to hear what you find also.
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