LPV Approaches

[flyingcatfish]

Just wondering if you need additional training to fly LPV approaches, if you do a GPS approach on your ride are you good to go?

[ahramin]

Private or commercial ops?

[av8ts]

From the AIM
3.16.5.2.5 RNAV Approaches with Vertical Guidance Based on WAAS

RNAV (GNSS) approaches with vertical guidance based on WAAS require a Class 2 or 3 (for LNAV/VNAV minima) or Class 3 (for LPV minima) TSO C145a WAAS receiver, or a TSO C146a sensor interfaced to appropriate avionics.

Your GPS has to have a class 3 WAAS receiver and for commercial operations the company would have to be TC approved. It would be in your company COM. Not sure for private operator

[Rockie]

As long as you're approved for GNSS approaches you can do them to LPV minimums assuming you have the requisite equipment. Authorization Required (AR) approaches are different and those you do need specific training and authorization for, but those approaches are labelled as such in the title and will also have a note in the information block.

[CID]

It's not just minima you have to consider. LPV has a vertical components that makes it more like an ILS.

http://www.tc.gc.ca/eng/civilaviation/p ... x8-961.htm

[Rockie]

It's not just minima you have to consider. LPV has a vertical components that makes it more like an ILS.

http://www.tc.gc.ca/eng/civilaviation/p ... x8-961.htm

So does LNAV/VNAV which must be flown vertically guided. The difference is LNAV/VNAV vertical guidance is barometrically derived whereas LPV is GNSS derived and therefore not subject to barometric errors.

[LPV]

LNAV approach's give vertical guidance as well as long as the GPS is WAAS equiped. No baro correction needed. You just treat the MDA as a DH. ILS's into everywhere. Beautiful

edit. question was about additional training. I believe you need SCDA (stabilized constant decent angle) training to do these approach's. I might be wrong. It's about not levelling off waiting for the MAWP.

[Rockie]

Well, you can use vertical guidance on an LNAV approach as well without WAAS. You just have to mind the temperature and ensure you don't descend below MDA unless you're landing, or you have the ops spec permitting you to while executing a go-around.

[CID]

Rockie, with respect to LNAV/VNAV, it is a precision approach but they don't lump it in with ILS and LPV. LNAV/VNAV won't give you the level of service of an LPV approach which is "near" CAT I ILS.

Furthermore, there are specific equipment requirements for LPV including dual WAAS systems. And then there is the issue with databases. You won't find LNAV/VNAV, LP or LPV approaches in databases for non-WAAS GNNS systems. So you won't be doing any RNAV approaches to LP, LPV or LNAV/VNAV minima without a TSO'd WAAS GNSS.

And you won't be doing LPV approaches until you show proficiency in ILS and/or LPV approaches, not LNAV/VNAV.

[Rockie]

LNAV/VNAV approaches are in non-WAAS databases because they don't require WAAS to do them. LNAV/VNAV approaches are not precision approaches either, they are still considered non-precision even though they have ILS like flight guidance (Baro-VNAV) and must be flown using that vertical guidance.

Non-ILS precision approaches will not be available until GLS procedures are approved (GBAS/LAAS as opposed to SBAS/WAAS for LPV), which will start out at CAT 1 but eventually progress to full CAT III autoland.

[CID]

Hmmmm....

You may want to read up on this. A precision approach is defined as one that has a lateral AND vertical guidance. Non-WAAS GNSS approaches that you can use the pre-WAAS VNAV guidance with are not the same as the WAAS LNAV/VNAV approaches or the pseudo-ILS approaches that some FMSs offer.

Here are a few links:

http://www.tc.gc.ca/eng/civilaviation/c ... 03-978.htm

http://rgl.faa.gov/Regulatory_and_Guida ... ght=20-138

http://rgl.faa.gov/Regulatory_and_Guida ... light=gnss

http://www.tc.gc.ca/eng/civilaviation/s ... r-1744.htm

http://fsims.faa.gov/PICDetail.aspx?doc ... 4F0076660E

And by the way, according to NASA and the FAA, SBAS will never reach CAT III. That's why they're still developing GBAS.

[Rockie]

I've read up on it a great deal actually.

Lateral Navigation/Vertical Navigation (LNAV/VNAV). An RNAV function that computes, displays, and provides both horizontal and approved vertical approach navigation. Both WAAS vertical guidance and baro-VNAV support approaches to LNAV/VNAV lines of minima.

Localizer Performance with Vertical Guidance (LPV). An RNAV function requiring WAAS, using a final approach segment (FAS) data block, which computes, displays and provides both horizontal and approved vertical approach navigation to minimums as low as 200 foot ceiling and ½ mile visibility.

When discussing precision/non-precision approaches you're really talking about minimums and design criteria. On an RNAV approach chart it is possible to get three different minima blocks. LNAV, LNAV/VNAV and LPV. Each has it's own design criteria and separate obstacle clearance requirements.

With regard to LNAV/VNAV, there is no such thing as WAAS LNAV/VNAV. You can however use WAAS systems to fly the approach, but that doesn't change the approach design criteria (temperature dependant obstacle clearance for BARO-VNAV and 250 HAT minimums among other things). Minimums will never be below that, and since the approach is designed to be used without the localizer performance or vertical guidance performance of SBAS it is considered a non-precision approach even though you're using vertical guidance.

LPV approaches derive their vertical guidance exclusively from SBAS systems and therefore are not effected by temperature. Design criteria is very much like an ILS and can be as low as 200 and a half.

And yes, I know SBAS will never provide minima below 200 and 1/2 which is why they are developing GLS and GBAS.

[pelmet]

[quote="Rockie"] LNAV/VNAV approaches are not precision approaches either, they are still considered non-precision even though they have ILS like flight guidance (Baro-VNAV) [/quote]

This wa my understanding as well and is very important in terms of alternate limits. LNAV/VNAV approach at your alternate along with only other non-precicion approaches to a forecast useable runway......use non-precision alternate limits.

Also if no ground based approaches available at the alternate.....do a RAIM check at your alternate for the appropriate time period that you will be arriving at your alternate.

[ahramin]

CID, that's an old definition of precision approach that doesn't take into account baro vnav. Dates from before vertical guidance FMS and GPS. LNAV/VNAV is most definitely not a precision approach.

[CID]

ahramin, baro-vnav has been around for decades just like the definition of precision approaches but that back and forth in semantics can go on forever.

With repsect to doing RNAV approaches with LNAV/VNAV minima without a WAAS capable GPS, I'd like to know exactly how you would do that. Where would you get your indication of the level of service? Non-WAAS GPSs don't have the ability to display the level of service for RNAV approaches that include vertical guidance.

According to the guidance information you need TSO-c145 or TSO-c146 equipment to do RNAV approaches to LNAV/VNAV minima. Don't get the old advisory VNAV component used with non-WAAS GPS confused with RNAV approaches to LNAV/VNAV minima.

You should not be using TSO-c129 GPS equipment to do RNAV approaches to LNAV/VNAV minima. I've never seen an op-spec that lets you do that.

[Rockie]

With repsect to doing RNAV approaches with LNAV/VNAV minima without a WAAS capable GPS, I'd like to know exactly how you would do that.

Read this line again, it's from one of the references in one of your earlier posts:

Both WAAS vertical guidance and baro-VNAV support approaches to LNAV/VNAV lines of minima.

[CID]

I've been remiss in not mentioning FMS systems that meet TSO-c115. They can certainly do RNAV approaches to LNAV/VNAV minma. They are certainly the exception. This is then more of a question of equipage than absolute ability to conduct the approach.

But I figured the original post had to do with GPS approaches not the newly defined APV approaches done with either a WAAS GNSS system or a TSO-c115 FMS with baro-VNAV in a pseudo-ILS configuration. As my previous reference to TSO-c129 alludes to.

So yes, what you say is true Rockie with respect to doing a baro-VNAV based LNAV/VNAV approach in an aircraft with a TSO-c115 FMS. But now tell me how for example, you would do an RNAV approach to LNAV/VNAV minima with a GNS-430 installed in an aircraft with baro-VNAV? The database wouldn't have the level-of-service criteria and the hardware wouldn't have the ability to annunciate it.

[Rockie]

But now tell me how for example, you would do an RNAV approach to LNAV/VNAV minima with a GNS-430 installed in an aircraft with baro-VNAV? The database wouldn't have the level-of-service criteria and the hardware wouldn't have the ability to annunciate it.

I push the button and there it is. Seriously, very very few airlines are equipped with WAAS although the FAA is pushing very hard for it. Transport Canada will in about 100 years. Any FMS/GPS equipped Boeing/Airbus/Embraer or what have you can do LNAV/VNAV approaches using BARO-VNAV.

I really don't know squat about TSO this or that, so can't help you there.

[CID]

There are plenty of WAAS equipped airlines out there. First Air has had their 737s outfitted for years. Don't know about TSO this or that? It's actually quite relevant to the discussion. If you read the links I provided you can learn about it or just check out the AIM.

[Rockie]

There are plenty of WAAS equipped airlines out there. First Air has had their 737s outfitted for years. Don't know about TSO this or that? It's actually quite relevant to the discussion. If you read the links I provided you can learn about it or just check out the AIM.

No there aren't plenty, there are a few. And I don't care about TSO's either because I am not equipping my own plane, I fly Air Canada airplanes and they worry about that kind of stuff. In fact as pilots we don't even have access to TSO information but still manage to get the job done properly. We concern outselves with procedures and knowing the TSO of the RNAV equipment isn't going to help that.

[CID]

Actually, you do. The AIM states:

3.16.5.2.1 RNAV Approaches with Lateral Guidance Only

RNAV (GPS) LNAV approaches do not define a vertical path through space; as such, each approach segment has a minimum step-down altitude below which the pilot may not descend. These are normally flown using the “level-descend-level” method familiar to most pilots.

GPS (TSO C129/C129a Class A1, B1, B3, C1 or C3) and WAAS (TSO C145a/C146a, any class) avionics are both able to provide the lateral guidance required for these approaches.

Without vertical guidance, pilots fly to the LNAV MDA line depicted on the plate. The pilot is required to remain at or above the MDA unless a visual transition to landing can be accomplished, or to conduct a missed approach at the missed approach waypoint (MAWP), typically located over the runway threshold.

WAAS and some TSO C129/C129a avionics may provide advisory vertical guidance when flying approaches without LNAV/VNAV or LPV minima. It is important to recognize that this guidance is advisory only and the pilot is responsible for respecting the minimum altitude for each segment until a visual transition to land is commenced.

Pilots using TSO C129/C129a avionics should use the RAIM prediction feature to ensure that approach-level RAIM will be supported at the destination or alternate airport for the ETA (±15 min). This should be done before takeoff, and again prior to commencing a GNSS-based approach. If approach-level RAIM is not expected to be available, pilots should advise ATS as soon as practicable and state their intentions (e.g. delay the approach, fly another type of approach, proceed to alternate).

It also mentions the TSO c115 based RNAV approaches to LNAV/VNAV minima.

And you can check here for the TSOs:

http://rgl.faa.gov/Regulatory_and_Guida ... t?OpenPage

But I see where you're coming from. Air Canada doesn't need WAAS. They don't even need GPS for the domestic routes. And I can see where you wouldn't concern yourself with what other airlines are doing. If you ever make your way up to the operations echelon at Air Canada you'll probably be well versed in the TSOs and the MNPS requirements of specific airspace in order to plan for equipage on the aircraft.

[Rockie]

Air Canada does actually need WAAS, they just don't know it yet, and in not too many years everybody will find it more difficult to be without it. The FAA is big into it and their airspace plans will largely depend on the accuracy it affords which is why they are pushing it so much.

Just because it states the TSO requirement in the AIM doesn't mean you have to know it. Air Canada equips the fleets with all kinds of TSO'ed equipment as I'm sure you're aware. The engineering and airworthiness types simply tell us what the equipment is certified for without feeling the need to attach a TSO number to it which seems to work just fine. Line pilots don't have to know the TSO number and I can tell you right now 99.9% of us don't, yet we still manage don't we?

[CID]

Rocky, I'm not sure if you're aware of this but WAAS has no coverage outside of North America so no, European airlines, unless you consider non-domestic service, have absolutely no interest in it. SBAS, the more general umbrella that WAAS and EGNOS fall under is a different story. EGNOS has been providing SBAS to European airspace since late 2009.

The development of EGNOS APV approaches has been rather slow with the schedule dragging on into 2016 (estimate).

I still don't think Air Canada needs WAAS though. They tend to fly pavement to pavement to airports serviced by ILS which contrary to previous estimates, will stay in service for awhile yet. WAAS or other SBAS systems will not replace ILS because it's technically not possible to make it perform any better than "near" CAT II and which has yet to be proven as the WAAS sensor OEMs test advanced solutions to make the position resolution come up to CAT II standards.

The only "egg" in the basket of the FAA right now for CAT III ILS replacement is GBAS. And you don't have to believe me or the FAA. Just ask Boeing. They currently don't offer WAAS upgrades to Boeing aircraft because they are feel GBAS is the future. All the WAAS upgrades on Boeing aircraft right now are third party.

As far as "future" requirements go, the only ADS-B rule on the books (FAA FAR 91-227 and corresponding commercial rules) show equipage mandates in 2020. And the Hudson Bay ADS-B airspace has no specific equipage date or position data any more accurate than a TSO-c129 GPS.

http://www.navcanada.ca/ContentDefiniti ... ure_EN.pdf

Of course GBAS won't help guys flogging Dash 8s into remote airports. They will rely on WAAS so GBAS won't replace WAAS it will compliment it providing extra accuracy for ILS-accuracy GNSS approaches where needed while providing CAT I precision approaches to places where no approaches would exist otherwise.

[PanEuropean]

...WAAS has no coverage outside of North America so no, European airlines, unless you consider non-domestic service, have absolutely no interest in it. SBAS, the more general umbrella that WAAS and EGNOS which has been providing SBAS to European airspace since late 2009...

Although your post is 'literally' correct, I think you have created a risk of confusion for readers who are not familiar with international operations.

SBAS (Satellite Based Augmentation Service) is the generic term - the ICAO term.

WAAS (Wide Area Augmentation Service) and EGNOS (European Geostationary Navigation Overlay Service) are the names of two different implementations of SBAS.

To make an analogy, SBAS is like saying 'facial tissue' and WAAS and EGNOS are like saying 'Kleenex'. SBAS is a generic term that describes all forms of this technology, and WAAS and EGNOS are 'brands' of SBAS provided by different operators (the FAA and TC in the case of WAAS, and the ESA in the case of EGNOS). There are some other operators out there who are either investigating or presently operating SBAS systems, including - quite seriously - John Deere, who operate their own SBAS to enable farmers to plow fields more accurately.

Michael

[CID]

Yes. WAAS and EGNOS are synonymous with SBAS being the umbrella under which they exist. I thought I made that clear but I seem to missing a couple of words in the sentence.

I actually don't think your Kleenex and facial tissue analogy works though. If SBAS=money then WAAS=US Dollar and EGNOS=Euro. WAAS is not merely a brand. It's a specific solution using satellites to rebroadcast the corrections received from ground stations. As opposed to GBAS which broadcasts the corrections directly to the aircraft from the ground station located on the airport.

(I edited the original post to clarify - see underlined)