david11
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RNAV Usage in IMC

Thu Jan 04, 2018 3:40 pm

Does anyone know of a larger airport in the US that actually uses RNAV (either RNP or GPS) approaches in IMC rather than an ILS. I know MDW 22L gets some usage in IMC (no ILS on the runway) but I'm looking for other examples. Ideally at a runway without an ILS because, if I understand correctly, even when flying an RNAV approach a pilot could use the ILS for vertical guidance. I'm looking specifically at vertical guidance on RNAV approaches.

EWR 29 is another example, but it doesn't seem to get much use in IMC.

Thanks!
 
Woodreau
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Re: RNAV Usage in IMC

Fri Jan 05, 2018 12:17 am

Until you get an RNAV approach with vertical guidance that can get you down to 300RVR, you're not going to find larger (air carrier) airports without ILS.

RNAV approaches are useful in smaller airports that don't have ILS, where you can use the RNAV to similar Cat I ILS minimums, where before RNAV they had non-precision VOR or NDB minimums.
Or you can use RNAV approaches for multi-segment curved approaches that don't have to be straight in to the runway.
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BravoOne
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Re: RNAV Usage in IMC

Fri Jan 05, 2018 12:22 am

EVENTUALLY......the ILS will be secondary to the RNAV (AR) approach, but that will take years to invoke. The ILS as we know it today will simply exist as a backup procedure.
 
david11
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Re: RNAV Usage in IMC

Mon Jan 08, 2018 7:12 pm

Woodreau, I agree with what you said and MDW 22L is a great example where the RNAV RNP X allows a smoothly curved approach from the west. But I would think some airports' ATC might use RNAV in IMC for spacing reasons during busy times?

And to be clear, I'm not looking for an airport without ILS - just a runway (e.g. MDW 22L, EWR 29, PHL 35)
 
aeropix
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Re: RNAV Usage in IMC

Mon Jan 08, 2018 9:02 pm

In Seychelles, FSIA/SEZ we use the RNAV RNP Z Rwy 13 approach to allow minima of 400ft and 1.4km visibility in a mountainous heavily constrained airport where the next best approach to that runway is actually the approach to the OTHER runway ILS 31 / Circle to land with 1270ft minima and 2.4km visibility required. In other words, without the RNAV approach to 13, the airport would be extremely weather constrained and many days airline operations would not be possible.
 
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zeke
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Re: RNAV Usage in IMC

Mon Jan 08, 2018 9:40 pm

ANC RNAV (RNP) Rwy 33
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32andBelow
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Re: RNAV Usage in IMC

Tue Jan 09, 2018 1:39 am

All over Alaska.
 
david11
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Re: RNAV Usage in IMC

Wed Jan 10, 2018 3:31 pm

Zeke, that looks like a very interesting candidate, thanks! I'll look into it.

Aeropix, sounds like another good one but I'm just looking at US.
 
N353SK
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Re: RNAV Usage in IMC

Wed Jan 10, 2018 3:39 pm

I’d think the one of the busiest would be San Diego’s 27. The runway has a localizer or RNAV approach and a majority of pilots tend to opt for the RNAV to get vertical guidance.
 
Woodreau
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Re: RNAV Usage in IMC

Wed Jan 10, 2018 4:27 pm

I forgot about the RNAV 27 into San Diego. I tend to use just the LOC 27 because, the minimums are lower for the LOC 27 than the RNAV 27, and the avionics provides vertical guidance to the runway with the LOC27. Either way approach will clear you for either one.
Bonus animus sit, ab experientia. Quod salvatum fuerit de malis usu venit judicium.
 
david11
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Re: RNAV Usage in IMC

Thu Jan 11, 2018 8:26 pm

Thanks for the continued responses everyone!

I looked at ANC runway 33 and it doesn't get much usage in IMC, and very few planes appear to be flying the RNP in general.

SAN 27 is the best suggestion yet! I see a fair amount of RNP usage there and some RNAV (GPS) as well during IMC. It slipped through the cracks of my initial search because I was looking at core 30 (ASDE-X airports have the best data) and SAN isn't core 30. But it does have ASDE-X! So great find, this'll be a good one to dig in to.
 
david11
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Re: RNAV Usage in IMC

Thu Jan 11, 2018 8:28 pm

Woodreau, when you refer to avionics vertical guidance are you talking about advisory VNAV or something else? I know some FMS give advisory VNAV on RNAV (GPS) but they can do that for LOC approaches as well?
 
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Starlionblue
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Re: RNAV Usage in IMC

Fri Jan 12, 2018 3:16 pm

david11 wrote:
Woodreau, when you refer to avionics vertical guidance are you talking about advisory VNAV or something else? I know some FMS give advisory VNAV on RNAV (GPS) but they can do that for LOC approaches as well?


The 350 can give vertical guidance provided by the FM on VOR, LOC and RNAV approaches using FLS. For that matter then FM can provide horizontal guidance as well. In simple terms you can fly a non-precision approach with guidance that looks like ILS.

There's some info here: http://www.ae-expo.eu/wp-content/uploads/2016/04/Frederic-Belloir-Airbus-xLS-concept.pdf
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Woodreau
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Re: RNAV Usage in IMC

Fri Jan 12, 2018 5:04 pm

david11 wrote:
Woodreau, when you refer to avionics vertical guidance are you talking about advisory VNAV or something else? I know some FMS give advisory VNAV on RNAV (GPS) but they can do that for LOC approaches as well?


I get a green dot on the right side of the PFD where the magenta diamond indicating the glideslope signal normally would be. it's computed by the FMGC and shows me where I am in relation to the vertical constraints of the waypoints.

San Diego is a little different as it's a -3.5 degree glidepath instead of the normal -3.0 glidepath. Once you turn the automation off, you lose the flight director. But I just fly the localizer signal and use the green dot to gauge where I'm at and leave the bird at roughly just below the -2.5 and monitor the vertical speed.
Bonus animus sit, ab experientia. Quod salvatum fuerit de malis usu venit judicium.
 
david11
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Re: RNAV Usage in IMC

Fri Jan 12, 2018 6:54 pm

Makes sense, I hadn't heard of FLS before but it's a neat concept. Thanks for the powerpoint link
 
VSMUT
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Re: RNAV Usage in IMC

Sat Jan 13, 2018 10:53 am

They do it in Berlin Schönefeld / Brandenburg all the time. The RNAV seems to be standard for approaches to 07L for some reason.
 
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TOGA10
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Re: RNAV Usage in IMC

Sun Jan 14, 2018 6:49 pm

When you're flying into LGW behind the EK 380, you'll do an RNAV as well. Apparently it has something to do with the impact on the ILS Loc beam when it vacates the runway..
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