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Is it me or my unit

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=1413
Printed Date: 01 May 2024 at 1:07pm
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com


Topic: Is it me or my unit
Posted By: Froethel
Subject: Is it me or my unit
Date Posted: 30 Sep 2017 at 2:19pm
For the past two weeks when I try to fly the following....KHWV...CCC...KISP and select the ILS 24 approach my trainer never activates the VLOC outside the FAF. Yesterday I actually tried to fly that approach in my plane and the same thing occurred. When I flew the ILS 6 approach however everything was great. Would some please fly this short flight plan on your trainer and let me know if it works for you. I called tech support and they told me they would get back to me....but nothing as yet from them. Thanks

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Frank



Replies:
Posted By: oskrypuch
Date Posted: 30 Sep 2017 at 2:23pm
Is the approach activated?

* Orest



Posted By: Froethel
Date Posted: 30 Sep 2017 at 2:57pm
Sure did.

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Frank


Posted By: mfb
Date Posted: 02 Oct 2017 at 9:58am
The PC or iPad simulator (trainer) never activates VLOC. It doesn't simulate VORs or localizers, so it can't flip into VLOC mode.

In the real airplane the IFD won't go into VLOC mode until five conditions are met for five seconds:

1) The next leg or the active leg terminates at the FAF
2) The aircraft is on the front side of the approach
3) The aircraft course is within 15 degrees of the final approach course
4) Cross track deviation is less than half a dot
5) The correct station is tuned and identified

These are detailed on page 5-21 of the IFD-540 manual.

Try intercepting the localizer a little way out on the approach and see if all of these points are satisfied. You can tell if the IFD has tuned and identified the station by looking at the Decoded VLOC IDENT datablock (IFD540 manual page 4-30). It won't show an identifier unless the station has been decoded by the IFD.

Mike






Posted By: 94S
Date Posted: 03 Oct 2017 at 5:56pm
Originally posted by mfb mfb wrote:

In the real airplane the IFD won't go into VLOC mode until five conditions are met for five seconds:

1) The next leg or the active leg terminates at the FAF
2) The aircraft is on the front side of the approach
3) The aircraft course is within 15 degrees of the final approach course
4) Cross track deviation is less than half a dot
5) The correct station is tuned and identified

These are detailed on page 5-21 of the IFD-540 manual.


Some of these seem to conflict with information given on page 5-12 of the IFD-540 manual (

P/N 600-00300-001 Rev 03).  The following is copied and pasted directly from the manual except that I am adding lettered bullets to avoid confusion with the numbered bullets above.


"To trigger the transition from armed VLOC to active VLOC, all of the following capture criteria must be met:

a) The tuned frequency in the nav radio matches that of the approach navaid;

b) The Morse code decoded by the tuned nav radio matches the identifier of the approach navaid;

c) The aircraft track is within 15 degrees of the final approach course;

d) The course to the active waypoint is within 45 degrees of the final approach course;

e) The radio deviations are at most 50% of full scale for 5 consecutive seconds;

f) The active leg is part of the approach up to and including the final approach fix."


a+b probably combine to equal 5.
c matches 3.
d doesn't have an obvious corresponding item from page 5-21, but maybe is how it determines that it is on the "front side of the approach", item 2.
e specifies half scale deflection, 4 specifies half dot deflection.  There's a significant difference there.
f only refers to the active leg as a trigger, 1 refers to next or active legs as a trigger.

AviSimpson, could you shed some light on this?  Is this just an editorial thing (aka typo), or is there actually something different going on between what is described on these two pages?


Posted By: AviSimpson
Date Posted: 04 Oct 2017 at 3:00pm
I think the PG can be improved here and will do so in the next release. The list on 5-12 is a more accurate wording.

As for the criteria, they are:

- Identifier Matches

- Frequency Matches

- Aircraft Course is within 15 degrees of final approach course

- Aircraft is on the front side of the approach (defined as the course to active waypoint within 45° of final approach course)

- Less than or equal to 50% Nav needle deflection

*The above items must be met for at least 5 consecutive seconds*

- Active or next Leg must terminate at the FAF

Of course, we'll only switch for VOR and localizer based approaches.  Maybe that's why the list got duplicated on 5-21.



-------------
Simpson Bennett
Avidyne Corporation
Product Manager


Posted By: 94S
Date Posted: 04 Oct 2017 at 3:42pm
Thanks Simpson!



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