OBS and Sequencing
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=2079
Printed Date: 21 Feb 2025 at 9:57pm
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com
Topic: OBS and Sequencing
Posted By: SoCalIFDpilot
Subject: OBS and Sequencing
Date Posted: 27 Sep 2020 at 3:49pm
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Friends - I was flying with my CFII today. We had an IFR approach loaded in the IFD540, and it was active. My instructor then said to go into OBS mode and fly to a specific fix, and hold on a radial. So I switched to OBS made, dialed in the radial, and navigated to the fix. Before I could enter the hold, however, the IFD sequenced back to the next leg in the loaded IFR approach. I read the Pilots Guide and the Bauer book, and it seems that this is normal behavior. So, these are my questions... 1. Am I correct...is what I've described the normal way the IFD handles this scenario? 2. Is there any way to disable this functionality? 3. Assuming there's no way to disable this functionality, how would I handle this request from my CFII? In other words, with an IFR approach already loaded, is there any way to go into OBS mode and then hold at a fix (for an indeterminate time) before the IFD sequences to the next leg in the IFR approach? Thanks everyone!
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Replies:
Posted By: dmtidler
Date Posted: 27 Sep 2020 at 4:48pm
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SoCalIFDpilot wrote:Posted By: Bob H
Date Posted: 30 Sep 2020 at 10:16am
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The IFD has robust Hold capability, which should always be used when a Hold is needed. If the instructor wants you to undertake a hold manually, he/she should use raw VOR data. OBS function is part of the flight plan so automatic sequencing is appropriate. It is a course to or from a FP waypoint. The Hold should be entered as the next waypoint in the FP. The only time OBS mode won’t sequence is if the OBS course doesn’t cross a FP leg or waypoint. It’s my understanding that GTN units in OBS mode don’t auto sequence, which may be setting an expectation for your instructor. There are lots of ways to teach the functionality of OBS mode. However, trying to force the IFD to behave in a manner that is incompatible with real world methods is not one of them. Teaching holds using OBS mode has no practical application. Teaching Holds using raw VOR data is an important skill to impart. ------------- Bob |
Posted By: SoCalIFDpilot
Date Posted: 30 Sep 2020 at 10:31am
Helpful. Thanks!
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Posted By: midlifeflyer
Date Posted: 19 Feb 2025 at 7:14am
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I was looking for an answer to a question and came across this thread. The question of holds aside, is there a way to pause /suspend sequencing in an IFD?
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Posted By: AviSteve
Date Posted: 19 Feb 2025 at 9:21am
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There is no button you can press to say "stop sequencing now". However, anytime you fly into a discontinuity, the FMS will stop sequencing. One option for getting a discontinuity is to do a direct-to to some waypoint that is not already in your flight plan. You could create a user waypoint a short distance in front of you and then enter direct-to that waypoint. Once you cross the waypoint, the FMS will stop sequencing. ------------- Steve Lindsley Avidyne Engineering |
Posted By: midlifeflyer
Date Posted: 19 Feb 2025 at 12:45pm
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Thank you. Yes, I know that a discontinuity suspends sequencing - the box as no idea what to do next. Had that happen to my client on a training flight. You don't see the discontinuity with a Garmin box but it happens there too. Interesting about forcing a discontinuity. I'm trying to think of situations where I'd want to. I may try a few scenarios on the simulator.
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