LPV 200'

Lance F

Lance F

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Lance F
Fog and low ceilings were the norm around the southeast yesterday morning. I delayed my departure from Atlanta area to Greenville, SC KGMU (abount 45 min flight) awhile because the AWOS there stayed stubbornly at 200'. However, when the vis came up from the earlier 1/4 mile to 5 miles I launched.
I had briefed the approaches the night before and had noted that the GPS RWY1 had LPV down to 200'. I don't think there are too many of those. The AWOS ceiling was still 200' when I got in the terminal area, so when the approach controller said they were using ILS Rwy1, I asked if she'd give me the GPS approach. She did, and it was great. At 200' there the runway was. I find it fantastic that satellites 12,000 miles away can do this for us. Finally justified my WAAS upgrade.
 
On one occasion this past summer, with the GS out at KSBY during runway renovations, LPV was the difference in me getting home and Piedmont Airlines not even being able to start the approach. Neat stuff, it is.
 
Interesting that on the GMU RNAV 1 the mins are NOT affected by presence or absence of runway lighting......
 
bbchien said:
Interesting that on the GMU RNAV 1 the mins are NOT affected by presence or absence of runway lighting......
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Dr Bruce,

The same is true for the ILS 1 at GMU, in both cases, the normal 1/4 reduction for the MALSF system isn't available, so 3/4 mile is the lowest "no approach light" visibility minimum.

You will see a lot of LPV200 approaches to runways without approach lights, the DH can be 200 ft, but the minimum visibility is 3/4 mile. As an example, see KLKR RNAV (GPS) RWY 6 approach.
 
HPNPilot1200 said:
WAAS is awesome. There are 200-1/2 mins on the LPV into ACK, TPA, and a few other places I have come across. It's starting to become more common I've noticed.
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As of 1/13/2011, there were 2366 LPV approaches in the IFP inventory, and 419 of these have a DH of 200 feet. More and more LPV approaches are being added with a 200 ft DH, and as time goes on, many of those already published are being lowered to 200 ft DH when they are reviewed.
 
JeffDG said:
Here's one to try out: 316' AGL MDA on a pure dive-and-drive RNAV (no vertical guidance)

http://204.108.4.16/d-tpp/1101/05408R22.PDF

Airport's up on a little plateau, so the runway itself is kind of the highest point for a while around.
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Does the approach have advisory vertical glidepath with a WAAS GPS, I would expect it would? If it does have advisory glidepath, and you fly the full procedure, some autopilots would have a tough time coupling due to the step down fix 2.7 NM from the FAF. A CIII autopilot could have trouble coupling.
 
John Collins said:
Does the approach have advisory vertical glidepath with a WAAS GPS, I would expect it would? If it does have advisory glidepath, and you fly the full procedure, some autopilots would have a tough time coupling due to the step down fix 2.7 NM from the FAF. A CIII autopilot could have trouble coupling.
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There's a 3.05 degree suggestion on the chart, but there's no WAAS (not LNAV+VNAV, just straight LNAV)
 
I just love how rock-steady the needles are on a LPV GPS approach.

Use it once, you're sold.
 
SCCutler said:
I just love how rock-steady the needles are on a LPV GPS approach.

Use it once, you're sold.
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Yep - you say to yourself - I'm such an awesome pilot, look at how steady those needles are!:ihih: Kind of goes to show how much of the "chasing" phenomenon on an ILS can be due to the technology used itself.
 
I just wish the FAA could get with the times and call and LPV freaking precision!
 
elmetal said:
I just wish the FAA could get with the times and call and LPV freaking precision!
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I would be nice, but it really doesn't matter to me. The major difference from a user perspective between an ILS and the LPV is the weather planning requirement for filing as an alternate. With the ILS, you usually require a 600-2 forecast whereas with the LPV, you have to base the weather forecast on the LNAV NPA minimums, which generally requires a weather forecast of 800-2.
 
Approaches to mins are cooler than cool.

:thumbsup:

me too on the needles centered on the GPS approach.....

Though a failed GS indicator can do that too -- good thing I was right seat with a safety pilot in the left!
 
John Collins said:
I would be nice, but it really doesn't matter to me. The major difference from a user perspective between an ILS and the LPV is the weather planning requirement for filing as an alternate. With the ILS, you usually require a 600-2 forecast whereas with the LPV, you have to base the weather forecast on the LNAV NPA minimums, which generally requires a weather forecast of 800-2.
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Yes but at the same time you can't file an alternate if the only one you're equipped for is GPS

so if that airport ONLY has rnav/lpv/lnav, etc, you can't file it as alternate, legally speaking,

or if it has an NDB and you don't have an adf

but I digress, most airports with a GPS approach have VOR or ILS so it's still legal, but the point still stands.

Of course you can file whatever would make it legal and fly whatever you feel like flying anyway

File what you plan, fly what you need
 
elmetal said:
I just wish the FAA could get with the times and call and LPV freaking precision!
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If they did that, it would actually slow down the commissioning of the approaches.

Precision approaches have a lot more requirements in terms of airspace protection and airport infrastructure. Even if there are no airspace obstructions, the airports would likely still have to do new obstruction surveys. Precision requires different clearances to objects on the ground, parallel taxiways, runway markings etc.

So, what's in a label? Isn't the min the important thing?
 
Ken Ibold said:
If they did that, it would actually slow down the commissioning of the approaches.

Precision approaches have a lot more requirements in terms of airspace protection and airport infrastructure. Even if there are no airspace obstructions, the airports would likely still have to do new obstruction surveys. Precision requires different clearances to objects on the ground, parallel taxiways, runway markings etc.

So, what's in a label? Isn't the min the important thing?
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most lpvs mirror an ILS anyway, I don't see why they just can't add an LPV to mirror every ILS out there...

that way I can have those nice stable needles!

Plus it sounds like if they need to do obstruction surveys and whatever else, as a plane flying in IMC, I'd say hell yes please!

I don't know... so when making an LPV approach they don't do all the things they do for an ILS? I'd hate to hit a house following the GS down to 200' because the FAA didn't want to treat it as precision. 200 feet AGL is damn precise to me!
 
JeffDG said:
There's a 3.05 degree suggestion on the chart, but there's no WAAS (not LNAV+VNAV, just straight LNAV)
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The fact that there's no LNAV+VNAV or LPV mins doesn't mean a 430W/530W won't give you LNAV+V advisory vertical guidance, and the presence of the 3.05-degree glide angle data suggests it will. Keep in mind that the LNAV+V advisory guidance is just that -- advisory. Only the LNAV+VNAV and LPV vertical guidance are true vertical guidance you may follow all the way to DH before initiating missed approach, and allow "sagging" below DH during the initiation of the missed. Descent on an LNAV+V must be stopped so you do not go below the published MDA at any point. As a result, if the ceiling is very near mins, you're better to "dive and drive" on an LNAV+V than to follow the GS needle, since that effectively raises the pseudo-DH -- the altitude at which you initiate the missed in order to not go below MDA at all.
 
elmetal said:
Yes but at the same time you can't file an alternate if the only one you're equipped for is GPS

so if that airport ONLY has rnav/lpv/lnav, etc, you can't file it as alternate, legally speaking,

or if it has an NDB and you don't have an adf
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You can do all the above if your GPS is a WAAS c146 "sole source" GPS like the Garmin 430W/530W (unless the particular approach is labeled "A-NA"). Just not with a non-WAAS c129 "supplemental" GPS like the non-WAAS 430/530.
 
elmetal said:
... so when making an LPV approach they don't do all the things they do for an ILS? I'd hate to hit a house following the GS down to 200' because the FAA didn't want to treat it as precision.
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If you hit a house while following the GS down to 200 AGL on an LPV approach, it won't be because "the FAA didn't want to treat it as 'precision.'"
 
Ron Levy said:
You can do all the above if your GPS is a WAAS c146 "sole source" GPS like the Garmin 430W/530W (unless the particular approach is labeled "A-NA"). Just not with a non-WAAS c129 "supplemental" GPS like the non-WAAS 430/530.
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I thought the rule was: If the only approach you're equipped for is GPS, you can't file the alternate.

so let's say airport XYZ has 3 GPS approaches, no NDB, no VOR, but they have a localizer approach, but the localizer is inop

Are you telling me that if you have WAAS you can file that as alternate? Because I was pretty sure the regs stated that if the GPS is the only approach you're equipped for at the alternate you cannot file it as alternate
 
Ron Levy said:
If you hit a house while following the GS down to 200 AGL on an LPV approach, it won't be because "the FAA didn't want to treat it as 'precision.'"
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well it just sounded like as soon as it becomes 'precision' more surveys come into play to make sure your clearance is that of an ILS.

So basically what it sounds like is that on an LPV, they don't use the same minimum clearance requirements as they do an ILS
 
elmetal said:
I thought the rule was: If the only approach you're equipped for is GPS, you can't file the alternate.

so let's say airport XYZ has 3 GPS approaches, no NDB, no VOR, but they have a localizer approach, but the localizer is inop

Are you telling me that if you have WAAS you can file that as alternate?
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Yes.

Because I was pretty sure the regs stated that if the GPS is the only approach you're equipped for at the alternate you cannot file it as alternate
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That was true until a few years ago. It is no longer true for c146 "sole source certified" WAAS GPS's like the 430W/530W. That's why the "A-NA" is being removed from GPS-based approaches -- so folks with that gear can use them for alternate filing purposes.

BTW, this issue is always hard to teach folks going for their IR because the answer varies depending on what GPS you have, and it is a question often asked on IR practical tests if the plane has a GPS.
 
elmetal said:
well it just sounded like as soon as it becomes 'precision' more surveys come into play to make sure your clearance is that of an ILS.

So basically what it sounds like is that on an LPV, they don't use the same minimum clearance requirements as they do an ILS
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I don't think that's true, but John is the expert on that. However, if you hit a house on an 200-DH LPV approach, it wasn't anything the FAA did or did not do unless they failed to follow their own orders, and that's awfully rare with regard to publishing approaches.
 
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elmetal said:
I don't know... so when making an LPV approach they don't do all the things they do for an ILS? I'd hate to hit a house following the GS down to 200' because the FAA didn't want to treat it as precision. 200 feet AGL is damn precise to me!
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I'm not saying that. And I'm not referring specifically to overlaying an LPV onto an ILS, just developing instrument approaches in general.

To add or change an approach, there is a checklist to verify that a number of airport design standards are met, then there is a checklist for environmental impact. Someone at the airport has to generate the checklists, which are then verified by the ADO and then by the ATO's flight procedures team, then it's developed and flown.

An existing approach may have obstructions such as trees or towers that penetrate one of the many imaginary approach surfaces that are defined by the FAA (threshold siting surface, part 77 surface, precision object free area, obstacle free zones, etc), but are ignored or lighted or trimmed or whatever when the initial approach is commissioned. To change it or add it, all of that needs to be verified.

Instrument approaches are closely tied to airport design in addition to obstructions. If you want to see just how complicated it all gets, see appendix 16 of AC 150/5300-13.
 
Ron Levy said:
Yes.

That was true until a few years ago. It is no longer true for c146 "sole source certified" WAAS GPS's like the 430W/530W. That's why the "A-NA" is being removed from GPS-based approaches -- so folks with that gear can use them for alternate filing purposes.

BTW, this issue is always hard to teach folks going for their IR because the answer varies depending on what GPS you have, and it is a question often asked on IR practical tests if the plane has a GPS.
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good to know! and yet another selling point for those people who don't trust WAAS as they do an ILS!
 
Ken Ibold said:
complicated process of making approaches you'll probably still be ok with WAAS even if it never gets labeled precision
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Got it!

ok so another question now: ILS cat 3. Can you theoretically do a cat3 on waas?
 
elmetal said:
well it just sounded like as soon as it becomes 'precision' more surveys come into play to make sure your clearance is that of an ILS.

So basically what it sounds like is that on an LPV, they don't use the same minimum clearance requirements as they do an ILS
Click to expand...

That is not true, they have the same obstacle requirements as an ILS and an up to date survey for an ILS may be able to be used. In the case of my airport, there is an ILS, but the survey was dated and not loaded into the FAA database, so it had to be repeated, plus both runways were included in the new survey in comparison to only one for the ILS.

To get the lowest minimums on an LPV, such as LPV 200, the airport needs to meet certain requirements including runway length, parallel taxiways, runway markings, and approach lighting systems. Without an adequate approach lighting system, a DH of 200 feet is still possible, but the visibility will be a minimum of 3/4 mile.
 
John Collins said:
No, it is beyon the capability of current WAAS.
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Due to inherent WAAS accuracy limitations, I don't think Cat 3 will ever be a WAAS capability, but the FAA has already demonstrated Cat 3 capability using the Local Area Augmentation System (LAAS). It's just not been fielded yet.
 
Ron Levy said:
Due to inherent WAAS accuracy limitations, I don't think Cat 3 will ever be a WAAS capability, but the FAA has already demonstrated Cat 3 capability using the Local Area Augmentation System (LAAS). It's just not been fielded yet.
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just need to equip that 152 for cat3 now..

brb
 
elmetal said:
just need to equip that 152 for cat3 now..

brb
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Gonna be expensive!!!

Even if WAAS could support a CAT 3 approach, your bird still needs 2 (maybe 3) autopilots, redundant nav source, radio altimeter, maybe an inertial nav system, and I think CAT 3 requires 2 crewmembers (which might be tough to get in after adding all that radio gear).

That would be the sickest 152 around.
 
COFlyBoy said:
Gonna be expensive!!!

Even if WAAS could support a CAT 3 approach, your bird still needs 2 (maybe 3) autopilots, redundant nav source, radio altimeter, maybe an inertial nav system, and I think CAT 3 requires 2 crewmembers (which might be tough to get in after adding all that radio gear).

That would be the sickest 152 around.
Click to expand...

Can you imagine showing up for a Cat 3 Authorization checkride in a C-152? :thumbsup:
 
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