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CDI not centering when flying using FMS

Printed From: Just Flight Forum
Category: Just Flight Products
Forum Name: L-1011 TriStar
Forum Description: Discussion area for L-1011 TriStar
Printed Date: 28 Nov 2020 at 11:41am

Topic: CDI not centering when flying using FMS
Posted By: jfwharton
Subject: CDI not centering when flying using FMS
Date Posted: 24 Feb 2018 at 1:01am
When I fly this aircraft using the FMS I have noticed that the CDI does not center when following a course between waypoints.  I use FS FlightControl to monitor my flight path and it shows the aircraft on course yet the CDI is not centered.  Most of the time it is full deviation left or right of course.  Is anyone else experiencing this issue?

Posted By: ThomasAH
Date Posted: 24 Feb 2018 at 12:57pm
The manual shows the HSI with CDI on page 27 and says:
"3. VOR/INS/NAV window – indicates which navigation source the HSI is using (VOR, INS or NAV)"

But when trying it (I used the FMC version) I could only make it show VOR (here the CDI works if tuning to a VOR on NAV1) or ILS (when tuning NAV1 to an ILS), but not NAV (like shown on page 139 with the INS version), I haven't tried this with the INS version yet.
The Radio/FMC switch was set to FMC, and the FMC contained a valid and active flight plan.

And I don't know exactly what the NAV/GPS switch on the GPS popup is supposed to do, maybe this can help here?

Posted By: jfwharton
Date Posted: 24 Feb 2018 at 4:45pm
The issue I have with the manual is it doesn't tell you how to use the FMS, just what the switches do.  And the example is for the INS not the FMS.  So I guess I'll keep working on it.  Thanks for the input.

Posted By: ThomasAH
Date Posted: 24 Feb 2018 at 6:20pm
Loading an FSX flight plan and then using "Load ATC RTE" makes it easy to get the waypoints programmed. For my test above I then did not use VNAV, so I did not need to adjust the altitudes in the FMC.
Everything else was easy enough to find out for me without using the manual, even though I don't have much experience with other FMC/FMS systems. I experimented a bit with changing the cruise altitude (which worked fine) and selecting the ILS transition for the arrival airport (which worked fine, too), but in the end I failed to line up with the ILS and had to do a manual go-around and at some point quit the simulator because the AP did behave in unexpected ways (due to pilot error), but it was a fun experience.

Maybe just try the INS?

Posted By: speedbird438
Date Posted: 07 Feb 2019 at 11:17am
Hi, if you're flying it with the FMC then use the GPS switch on the GPS panel view. Once you'r eon approach and want to pick up the ILS approach - turn the GPS switch to NAV and so long as you've set the ILS frequency properly you'll be able to pick up the ILS.

Over 20 year FlightSim P3DV4, XP11 FSX

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