DME error? What did I do?
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=2054
Printed Date: 27 Apr 2024 at 11:23am
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com
Topic: DME error? What did I do?
Posted By: 260SE
Subject: DME error? What did I do?
Date Posted: 20 Aug 2020 at 12:04am
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We had something goofy happen on an instrument training flight, and hopefully it was pilot programming error. IFD-540. My airport doesn’t have a DME arc, so we decided to fly a pretend 9 DME around our VOR. -I set up the VOR frequency in NAV1. -I then used my HSI to fly the arc (connected to NAV1). -I also programmed my IFD for Direct-To the VOR so I could see my distance from the station (DME) -I then turned the IFD’s CDI knob to VLOC, but did not turn the IFD OBS knob at all. I had no plans to use the maps page on the IFD, so I just used my HSI. What happened next and why I’m not sure, but we ended up pointing the plane outbound because it seemed like we were getting blown towards the VOR according to the DME mileage. What we think might have happened is that the IFD was showing us cross-track distance to the radial we wanted, rather than distance to the station. It took us a few turns away from the station and a few radials later and a recheck of winds aloft calmness to figure out the distance in the IFD magenta waypoint box was not our distance to the station. What did I screw up?
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Replies:
Posted By: Bob H
Date Posted: 20 Aug 2020 at 9:58am
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Hard to know. What distance were you monitoring? TkDist or Direct Dist?
------------- Bob |
Posted By: 94S
Date Posted: 20 Aug 2020 at 11:22am
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The IFD displays Along-Track-Distance in the FMS waypoint blocks. So, if you were using the FMS waypoint blocks for your distance, the distance along the programmed Direct To route would decrease as you proceed around the arc. What you want to use in your case is either the "To Waypoint Direct Info." or "To Waypoint Direct Distance." data block (one just gives more info than the other). They can be placed in the fixed left side data blocks so they are visible on the FMS page, or in the scrollable right side data blocks visible on the MAP page.
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Posted By: 260SE
Date Posted: 20 Aug 2020 at 11:41am
| Awesome, thank you. I had the “To Waypoint Information” block on the right of the Map page. I thought it displayed distance similar to “To Waypoint Direct Info”, but I now see that’s not the case. The former shows “TkDist”, the latter “Dist”. |
Posted By: Bob H
Date Posted: 20 Aug 2020 at 11:56am
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Also, note that instead of modifying a datablock on either the FMS page or MAP page, just go to the nearest VOR page and get the distance and bearing information right there. ------------- Bob |
Posted By: AZ Flyer
Date Posted: 21 Aug 2020 at 10:44am
I discovered this is also the data block to use to see distance from the hold point when flying the outbound leg (for a distance-defined holding pattern). ------------- Stan |
260SE wrote: