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frankbell View Drop Down
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Points: 96 		Post Options Post Options   Thanks (0) Thanks(0)   Quote frankbell Quote  Post ReplyReply Direct Link To This Post Topic: VTF
    Posted: 11 Jan 2022 at 1:42pm
On my old Garmin 530, I was used to setting up an approach to fly to a fix on the approach, then being able to hit PROC, and select VTF "on the fly".  So far as I can see, there's not a way to do that on the 540?  You can set up the approach as a VTF when you initially select it, but not afterwards.  Of course, the alternative is to activate the next leg, though that takes a few more button pushes.

Am I missing something?
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Ibraham View Drop Down
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Points: 357 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Ibraham Quote  Post ReplyReply Direct Link To This Post Posted: 12 Jan 2022 at 2:35pm
The only way to do that is to push  PROC, select same approach but chose Vectors, which will replace the active approach with VECTORS. I have tried to avoid selecting VTF as it deletes all the fixes prior to the FAF. 

Last week we were flying a VFR practice approach RNAV 28R into KHWO. We were East of CUDES which is the intermediate fix, we were instructed to intercept the final approach course. At that point we replaced the approach with the VTF one, the IFD drew a course line from the MAP (JUMUV) to the FAF (CIBIB) and beyond. We intercepted that course and ATC then advised that we were north of the final approach course, which is very close to the KFLL final approach. 

The segment from IF to FAF is 275 degrees, but the VTF segment from FAF to MAP is 269 degrees, which is also not lined up with the runway (276 degrees). The best option would have been to activate the leg between IF and FAF or go direct to the IF (CUDES).

Lesson learned, will not select VTF again, as you lose all the waypoint before the FAF and all the intermediary segments and can end up off the expected/cleared course.
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frankbell View Drop Down
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Points: 96 		Post Options Post Options   Thanks (0) Thanks(0)   Quote frankbell Quote  Post ReplyReply Direct Link To This Post Posted: 12 Jan 2022 at 9:55pm
Thanks, and agreed, I don't like to select VTF initially for the reasons you gave.  Usually handy though, when you're told "heading ***, intercept the final, cleared for the approach". 
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frankbell View Drop Down
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Points: 96 		Post Options Post Options   Thanks (0) Thanks(0)   Quote frankbell Quote  Post ReplyReply Direct Link To This Post Posted: 12 Jan 2022 at 10:02pm
Didn't mean for the above to post like that... it's unusual for the VTF to not be lined up with the initial segment.  So in the case you described, not a good solution. 
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jhbehrens View Drop Down
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Points: 122 		Post Options Post Options   Thanks (0) Thanks(0)   Quote jhbehrens Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jan 2022 at 4:51am
However, given you were told to intercept the final approach course, you did as they asked and I find it objectionable that ATC called you for being too far North.
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chflyer View Drop Down
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Points: 1022 		Post Options Post Options   Thanks (0) Thanks(0)   Quote chflyer Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jan 2022 at 12:37pm
I agree with jhbehrens.

On the KHWO approach, did ATC give you a heading before or with the clearance? A clearance to intercept the final approach course is a clearance to intercept 269 course, not 275. According to the IFD screenshot, heading was 134 and in this case one should never pass south of the 269 magenta course line shown on the IFD. When being vectored, ATC should only clear to intercept the final approach course when they have you on an intercept heading, which is not the case here. Sounds like ATC wasn't on their A-game that day.
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Ibraham View Drop Down
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Points: 357 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Ibraham Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jan 2022 at 3:28pm
Sorry for the confusion, the IFD screenshot is from the simulator to depict the VTF leg provided on the IFD, we were actually East Southeast of CUDES, we did get a heading to intercept the final approach course (I guess ATC expected the extended segment from CUDES to CIBIB with heading of 275). The heading we were given would have intercepted that leg East of CUDES, which would make impossible to activate the leg, and selecting VTF deleted CUDES and provided a different leg to intercept. That was what was confusing. In the future, we will request to proceed direct to the IF (CUDES in this case) to stay on the published approach.

We have flown this approach several times in the past. We were always vectored to intercept the segment between CUDES and CIBIB, we activated leg to CIBIB and intercepted that leg.
In retrospect, VTF is a bad idea unless it is an ILS approach or all the segments line up. 
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dmtidler View Drop Down
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Points: 616 		Post Options Post Options   Thanks (0) Thanks(0)   Quote dmtidler Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jan 2022 at 6:15pm
Originally posted by Ibraham Ibraham wrote:

Sorry for the confusion, the IFD screenshot is from the simulator to depict the VTF leg provided on the IFD, we were actually East Southeast of CUDES, we did get a heading to intercept the final approach course (I guess ATC expected the extended segment from CUDES to CIBIB with heading of 275). The heading we were given would have intercepted that leg East of CUDES, which would make impossible to activate the leg, and selecting VTF deleted CUDES and provided a different leg to intercept. That was what was confusing. In the future, we will request to proceed direct to the IF (CUDES in this case) to stay on the published approach.

We have flown this approach several times in the past. We were always vectored to intercept the segment between CUDES and CIBIB, we activated leg to CIBIB and intercepted that leg.
In retrospect, VTF is a bad idea unless it is an ILS approach or all the segments line up. 

Two additional techinques for being vectored to intercept the extended approach course east of CUDES:

  1. You could use OBS mode to CUDES. To be the most accurate, I would personally set an OBS course of 276 degrees (vice the charted 275 degree) because 276 degrees matches what the IFD measures the magnetic course between CUDES and CIBIB to be. See picture below. Setting the charted course of 275 introduces a visible one degree kink in the route at CUDES.  



  2. You could alternatively Activate Leg to CIBIB. This is probably quicker to set into the IFD than OBS mode and will give you proper CDI/HSI course guidance to CIBIB even to the east of CUDES. The possibly uncomfortable part about this technique is that even though the IFD is giving proper course guidance, the magenta line does not extend to the east of CUDES. Also, since CIBIB becomes the active waypoint with this method, CUDES would have to be identified by some other method (such as 5.3 NM before CIBIB per the approach chart). See picture below.





Edited by dmtidler - 13 Jan 2022 at 6:44pm
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chflyer View Drop Down
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Points: 1022 		Post Options Post Options   Thanks (0) Thanks(0)   Quote chflyer Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jan 2022 at 6:36pm
An extension of the CUDES-CIBIB leg east of CUDES is not part of the approach nor is it the final approach course. That would be the VTF leg shown on the IFD that you actually flew to intercept. I would maintain that you correctly flew the clearance given to you by ATC. If ATC expected you to intercept the CUDES-CIBIB leg, then they should have given you a heading to intercept that leg. I agree with your conclusion that next time you should request direct to CUDES or a heading to intercept the CUDES-CIBIB leg.

The suggestion to use OBS to CUDES is a good alternative, but I personally would want ATC confirmation as that is not the clearance they gave. If you flew that without clarification they would be justified asking why you turned inbound before intersecting the final approach course.


Edited by chflyer - 13 Jan 2022 at 6:39pm
Vince
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dmtidler View Drop Down
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Points: 616 		Post Options Post Options   Thanks (0) Thanks(0)   Quote dmtidler Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jan 2022 at 7:39pm
My post was simply an offer of a couple of techniques to set the IFD up to intercept an extended approach course beyond the actual start of a published approach. The post just prior to mine indicated a possible lack of known techniques to accomplish that.

I totally agree that if an ATC clearance is at all ambiguous or confusing, ATC clarification is absolutely necessary.
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