KAP140 coupled approach question

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Rich
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Re: KAP140 coupled approach question

Post by Rich »

Here is a thought experiment, a case where full coupling might be undesirable. An example is the LDA-A for Vancouver, WA (KVUO):

This approach uses the localizer for RWY 10L ILS into Portland (KPDX). But being just a dumb radio, I assume if you tune into that localizer, it will also helpfully tune into the GS antenna. If you wind up flying the GS you'll wind up higher than the MDA for the LDA-A at the MAP - as much as 180 ft. In some IMC situations this could be undesirable. In reality to fly this approach "by the book" you need to hand-fly or avoid capturing the GS, flying below it all the way. Realistically if you don't break out well before the MAP you'd be hard-pressed to get yourself onto the runway given the actual MAP/MDA location/altitude.

In reality ATC is very resistant to granting this approach. The two times I've flown IFR into KVUO they wouldn't clear me for it. Once was in VMC and they were super-obnoxious. I requested it and they simply said "unable - fly heading [yadayada] and say intentions". The other was legitimate IMC with marginal ceilings below and they had me use the VOR-A to PDX, break off and scud-run to the destination.

I wonder how common this kind of situation is.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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perossichi
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Re: KAP140 coupled approach question

Post by perossichi »

Rich is right that there is no obligation to keep you low, but I've flown probably over 50 LP approaches to different airports and I'm typically cleared to an IAF at the min altitude at that IAF. The 530W will create a GS using GPS information and the KAP 140 will fly it (as long as you first allow AP instructions to flow to KAP 140 from the 530W using a PROC menu item).

LP approaches are not LNAV approaches as there is a much higher standard of lateral guidance (.3 at the FAF reducing to 700 ft over the threshold.). You can certainly fly one to LNAV min but why would you do that?
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Re: KAP140 coupled approach question

Post by perossichi »

More. If you look at the regulations for ATC, AIM section 5.9, it states:

2. Paragraph 5-9-1-b: "For a precision approach, at an altitude not above the glideslope/glidepath or below the minimum glideslope intercept altitude specified on the approach procedure chart"

this means that they are supposed to vector you in no less that 3 miles from the FAF (2 miles outside the approach gate) at an altitude that is below the GS.

Note that this is for precision approaches only.

I got this from a very interesting document prepared by a LA ARTCC controller called "A controllers guide to instrument approaches" -- no longer available on the web. Available from my drop-box. A very good read for any instrument pilots.


https://www.dropbox.com/scl/fi/h727rsn2 ... f12gmdp24i
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Re: KAP140 coupled approach question

Post by Rich »

perossichi wrote: Tue May 25, 2021 12:39 am More. If you look at the regulations for ATC, AIM section 5.9, it states:

2. Paragraph 5-9-1-b: "For a precision approach, at an altitude not above the glideslope/glidepath or below the minimum glideslope intercept altitude specified on the approach procedure chart"

this means that they are supposed to vector you in no less that 3 miles from the FAF (2 miles outside the approach gate) at an altitude that is below the GS.

Note that this is for precision approaches only.

I got this from a very interesting document prepared by a LA ARTCC controller called "A controllers guide to instrument approaches" -- no longer available on the web. Available from my drop-box. A very good read for any instrument pilots.
"supposed to" and note that no RNAV approach is a technically a precision approach. My experience has been different than yours.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Re: KAP140 coupled approach question

Post by Rich »

Something to point out is the conditions that contribute to the less-than-ideal ATC situation around here. If you look at the Klamath Falls sectional for the area around Redmond you will note that there is only the Class D for the airport and the only VOR within ~100 miles is less than 2 nm outside the lateral boundaries of that airspace. Couple that with scads of training based out of Bend and Redmond going on using that VOR (with and without contacting ATC) practicing holds and such, all the airways for which this VOR is a fix, RDM having the only ILS within 100 miles to RWY 23, lots of local traffic doing who-can-guess-what, and our local ATC has all sorts of problems keeping planes separated. We even got a dedicated sub-sector (roughly 30 miles on a side) for ATC communication a couple of years ago to cut down on congestion on the main sector frequency. Last year they put out a request for local pilots to voluntary monitor that local frequency (126.15) and to squawk 1237 so they can see ADS-B info displayed and know that you're monitoring their frequency.

The typical good-weather day around this area looks like Walmart on Black Friday.

So when they know I'm practicing stuff in VFR conditions they may not be able to get me to more usable altitudes in the interest of keeping traffic separation and not vectoring me all over the place to avoid traffic over which they not only have no control but no idea WTH it's doing or plans to do. They deal with numerous conflicts all the time resulting aborted approaches by airlines as well as other flights. This is astoundingly common here.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Re: KAP140 coupled approach question

Post by nathanda40 »

Does anybody know if there is a reason that a DA40 with 6-pack (HSI) and KAP140 would not capture the glideslope from an LPV approach? It works fine on an ILS but doesn't seem to want to do vertical on GPS approaches.
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Re: KAP140 coupled approach question

Post by Rich »

nathanda40 wrote: Tue Jun 29, 2021 4:48 pm Does anybody know if there is a reason that a DA40 with 6-pack (HSI) and KAP140 would not capture the glideslope from an LPV approach? It works fine on an ILS but doesn't seem to want to do vertical on GPS approaches.
I have had different cases of this over the years:
1. Installation of WAAS upgrade from the GNSx30 to GNS x30W failed to make a required connection from the 530W to the AP.
2. I had to reseat the 140 FC in the panel.
3. Delay hitting approach mode in the 140 until it starts blinking "APCH" in the display.
4. The plane essentially has to encounter/collide with the GS to capture it. It won't seek it out if, for example, you're above it holding altitude.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Rich
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Re: KAP140 coupled approach question

Post by Rich »

Rich wrote: Tue Jun 29, 2021 5:34 pm
nathanda40 wrote: Tue Jun 29, 2021 4:48 pm Does anybody know if there is a reason that a DA40 with 6-pack (HSI) and KAP140 would not capture the glideslope from an LPV approach? It works fine on an ILS but doesn't seem to want to do vertical on GPS approaches.
I have had different cases of this over the years:
1. Installation of WAAS upgrade from the GNSx30 to GNS x30W failed to make a required connection from the 530W to the AP.
2. I had to reseat the 140 FC in the panel.
3. Delay hitting approach mode in the 140 until it starts blinking "APCH" in the display.
4. The plane essentially has to encounter/collide with the GS to capture it. It won't seek it out if, for example, you're above it holding altitude.
Don't take offense but I need to add that your navigator must be a WAAS-capable one. None of the six-packs were delivered by Diamond with WAAS capability, as it was not yet available for the GNS units. So some sort of conversion/upgrade is subsequently required.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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