denverpilot
Tied Down
Forgetting to flip the CDI mode is one of the most common fails by candidates around here.
At least before the current AIM guidance.
Haven’t heard lately.
VOR-A with a Garmin 430
- Thread starter Betmerick
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Forgetting to flip the CDI mode is one of the most common fails by candidates around here.
At least before the current AIM guidance.
Haven’t heard lately.
So, if you're on a VOR/DME approach and the DPE "fails" your GPS, you should discontinue the approach, because you lost your DME component, right? (Assuming plane doesn't have DME receiver and you're using the 430 for DME).
EdFred
Taxi to Parking
For the approach that started this thread? Yes. For every single one? I would say yes, but someone will probably dig out some approach from who knows where that would allow you to continue for some reason.
texasclouds
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No GPS/DME? Should have plate option for Timed FAF to MAP.
EdFred
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The approach in question does not. And that might be due to the distance from the VOR.
Right. In the "DME Required" approach in this thread, as @EdFred said, yo have lost a required component of the approach
and there is no way other than DME (or certified GPS) to legitimately identify either the FAF or the MAP.
Of course, if there is no way to identify the MAP (nor the MAP Hold), you have issues other than simply discontinuing the approach!
aterpster
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aterpster
VOR approaches that require DME (formerly titled VOR/DME) will not have a timing table.
EdFred
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I was hesitant to say all, because there almost always seems to be an exception to the never/all statement, which is why I only addressed the approach in question.
But even if it's "generally speaking," it's still due to it being a VOR/DME approach (under the old nomenclature), not due to "distance from the VOR."
EdFred
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I was addressing more why the DME was probably incorporated into the approach. There's a ton of VOR approaches out there without a DME component, but the ones I've seen have always been much shorter. (like the one into my home field)
Timing on a 20+ mile approach without knowing your GS could put you way short or way past on a 20+ mile leg. (Pre GPS days)
You keep on coming up with things I never said to argue with. I never said I never hit a CDI button, any more than the I fly the approach on Nav2 (the last thing you made up to argue with). I said I keep my primary Nav - NAV 1 - in GPS mode. IOW, don't hit the CDI button on my primary Nav. It stays on the GPS. I set up NAV 2 (whether vanilla VOR, including the OBS for the FAC, or a second GPS) during a low workload point in the flight - almost literally as soon as I know I am going to use a VOR approach. Last time I did one it was for my IPC. Knowing we were going to do the nearby VOR A at some point, NAV 2 (except for identification) was set up before we ever left the ground.
Done. If you want to continue to switch CDIs on Nav 1 as was once arguably required, go right ahead. Nothing wrong with it. Just a different technique.
aterpster
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aterpster
There have been a few VOR/DME IAPs with timing tables because the procedures specialist completed the form 8260-5 incorrectly.
But Ed raises a good question. Is the reason (or at least "a" reason) for requiring DME on what otherwise looks like a plain vanilla VOR approach the distance from the VOR to the MAP or other factors? On the one we have been discussing, it's 23.1 miles from the VOR to the MAP; that's a lot of timing estimation.
wsuffa
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Looks like the missed approach requires DME/distance
EdFred
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Yes, but WHY?
This one does not:
https://aeronav.faa.gov/d-tpp/1909/05778V12.PDF
Yes, it has the DME distance, but guess what the VIO DME is OTS right now.
(VOR 12 at 9D9 in case the link goes dead in the future)
That's true. And there aren't other viable VOR options other than returning all the way to the two nearby VORs. But that alone would be a reason for DME required for the missed approach segment, not necessarily for the extended FAC.
The approach into Hastings has DME distances, but DME isn't required for anything related to navigation (other than the optional step-down and lower minimums). You may well be right about distance being one of the factors making a vanilla VOR approach unfeasible, but If you look at the GPC VOR-A in the context of the enroute structure, there's pretty much nothing which would not require DME or a legal substitute except a missed going all the way back to VHP or forward to HUF.
wsuffa
Touchdown! Greaser!
Well, there's no PT at VHP, and it's stated that the approach is NA for airways arriving at VHP from 184 CW 278. Other than the stated approach path, the MSA is 3100 w/i 25 NM of VHP. VHP is under/within the outer ring Indy Class B, and VHP is used for many of the DPs at KIND as well as being just off the ILS-14 at KIND, so I'd expect that to be a problem. Likewise TTH is used for approaches at KHUF - and NA on routes back to the approach.
So, I'm not surprised at the MAP for this approach.
wsuffa
Touchdown! Greaser!
But that has two sets of minimums - one with DME, one without. The "no DME" minimum is the same as the crossing altitude at JCUBS so it's dive-and-drive. Then MAP is the VOR. So really no DME required unless one wants to take advantage of the lower minimums. As such it has the timing table since DME is not required.
EdFred
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Let's go back to the beginning, before the plates are even made. Blank sheet. We have two airports, and two VOR/DME stations.
During the construction of the approaches, why was the VOR approach into Greencastle made to require DME, when the approach into Hastings was not. We aren't talking about the differences on the plates, but WHY were the differences made during construction? Was it because of the distance from the station to the airport? That's the WHY that I am asking, not why are they different now, why were they constructed differently.
Alert ATC, go missed, ask for vectors to another approach you can do?
EdFred
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The question was more rhetorical, as I know the answer.
My question was not rhetorical. I know that you know the answer. Not having much recent experience I question whether I know the answer.
I think I might have seen DME required to find holding fix even where there is a time table to find the MAP. Not positive, though.
EdFred
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HA! Yes. If any part of the knowing of the distance fails, the approach is either not initiated, or abandoned.
RussR
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Distance from the VOR is NOT a factor in determining whether or not there is a timing table. Remember, the timing table is not from the VOR to the MAP, it's from the FAF to the MAP. So, regardless of how far away the VOR is, the final segment is still usually somewhere around 3-10 nm long.
Whether or not there is a timing table is solely determined on how an aircraft is going to identify the MAP.
Whether or not there is a timing table is solely determined on how an aircraft is going to identify the MAP.
RussR
En-Route
Typical example of nearby VOR geometry affecting design.
The 9D9 VOR RWY 12 has a VOR that is close enough to the field to serve as the FAF. Final length is 9.7 nm, an optional stepdown is included if you have DME, but since DME is not required there is a timing table. If there was a suitable nearby VOR off to the side, the stepdown fix could also have been identified with a VOR radial, but there does not appear to be such a VOR.
The GPC VOR-A, on the other hand, is too far from the field to serve as a FAF itself, at 23 nm away. The maximum length from FAF to MAP for a VOR approach is 10 nm. So additional fixes along the inbound course are required, in this case the IF at 10 DME and the FAF at 18 DME for a final segment length of 5.1 nm. Since there are no good nearby VORs for crossing radials, the only way to identify these fixes is by DME. And since DME is required to fly it, there is no need for a timing table.
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aterpster
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A VOR IAP with FAF, can have the furthermost part of the final approach segment as far as 30 miles from the facility. This could be done without DME if there are crossing radials of sufficient accuracy. In such a case the timing is only from crossing the radial for the FAF to the MAP.
So on the approach we e been discussing, it's the lack of alternative ways if identifying the FAF, etc than distance?
Thanks.
RussR
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Yes, a timing table or lack thereof has nothing to do with the length of final or how far away the VOR is.
aterpster
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Here is one at my former home drome. DME for every fix. But, there are also radials from SLI. So, it is not "DME Required" and it must have a timing table for the pilot without DME. When possible, they should be built this way, both with DME and crossing radials. (That is, if they are making these any longer.)
Oddly, it doesn't provide a DME fix for the MAP. It provides a computer fix and the timing table. I guess you can intuit that it's at 12.2 DME, but odd they didn't put a DME flag there.
aterpster
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Beats me. That is the way the source document reads. Having said that, Jeppesen charts both the 12.2 DME and the CNF.
So they did the arithmetic (I hesitate to call 6.3+5.9 "math"
)
aterpster
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It's been 12.2 DME since the approach was implemented in the 1960s. They made a new original when they deleted the "or GPS" last year.So they did the arithmetic (I hesitate to call 6.3+5.9 "math"
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I made the comment because of the old "are you allowed to create your own timing" discussions
aterpster
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Jeppesen makes the choice easy. The CNF seems useless since it is no longer an overlay IAP.I made the comment because of the old "are you allowed to create your own timing" discussions
Well, if one flies the approach using GPS as primary with backup Data in NAV2, it still means something to the GPS prompting for or sequencing to to the missed.
Of course, much of the whole discussion of GPS use on VOR approaches can seem useless. To use the originally-discussed GPC VPR-A scenario, it would be rare for a pilot in the real IFR world to opt for the VOR-A circle to land when there are straight-in GPS approaches to both ends of the runway.
People sure like to obfuscate things around here.
Just tune the VORTAC, and select the NAV for the HSI and fly the CDI. Use the DME display for the fixes.
Easy.
Just tune the VORTAC, and select the NAV for the HSI and fly the CDI. Use the DME display for the fixes.
Easy.