FAA Draft AC 90-119 to make RNAV LPV Approaches classified as 'Precision Approach'!

[hammdo]

https://bruceair.wordpress.com/2021/05/17/draft-ac-90-119-performance-based-navigation-operations/
 

Looks like this is going to happen...

-Don

[GeeBee]

It is about time.

 

 

[PT20J]

Probably a necessary precursor to eliminating more ILS installations.

[David Lloyd]

I believe a lot of pilots where using their GPS in this fashion all along.  Much easier to do than tune, identify and follow the wandering needles of a VOR receiver.

[Mooney Dog]

Wow thats some interesting news. Im surprised honestly, but glad its happening. 

[Will.iam]

Until the first big solar flare or something else knocks out the GPS signal then everyone will be scrambling for VFR or one of those ancient airports with an ILS.  Kind of reminds me of Texas slowly relying more and more on wind generators and solar power to only find out in an ice storm the wind generators freeze up and snow covers the solar panels. Now if the AHRS can keep the drift below the RNP requirements of the approach for an hour that would at least allow planes stuck in IMC to descend shoot an RNAV approach if you lost the GPS signal. I don’t know what the drift rate is on these AHRS systems.    

[Mooney Dog]

1 minute ago, Will.iam said:

Until the first big solar flare or something else knocks out the GPS signal then everyone will be scrambling for VFR or one of those ancient airports with an ILS.  Kind of reminds me of Texas slowly relying more and more on wind generators and solar power to only find out in an ice storm the wind generators freeze up and snow covers the solar panels. Now if the AHRS can keep the drift below the RNP requirements of the approach for an hour that would at least allow planes stuck in IMC to descend shoot an RNAV approach if you lost the GPS signal. I don’t know what the drift rate is on these AHRS systems.    

There is the concept of GBAS as well as SBAS for GPS systems. Its also just as easy to jam GPS as it is ILS.  No system will be 100%. That said, a modern LPV is much cheaper to set up and install and takes you to the same spots an ILS will take you to. 

 

Also i would just like point out here... In Texas the wind farms didnt actually freeze up, and solar did its job. there are also places MUCH colder than Texas that rely on wind power that dont have those power problems. Also the plants here never paid to get winter equipment so they where totally unprepared. 

[tony]

This document is for conducting  Performance-based Navigation (PBN) operations.  That's a concept that specifies the availability and an accuracy of the nav solution. These systems are what's required to fly in RNP airspace. It requires a DO-236 FMS.   We don't have that equipment in our little bug smashers.  we just have a GPS receiver.  

This document is consolidating, for the operator, a lot of regulations that are sprinkled about in other regulatory documents into one place.  So I don't know what your all getting excited about.  

 

[jaylw314]

10 minutes ago, tony said:

This document is for conducting  Performance-based Navigation (PBN) operations.  That's a concept that specifies the availability and an accuracy of the nav solution. These systems are what's required to fly in RNP airspace. It requires a DO-236 FMS.   We don't have that equipment in our little bug smashers.  we just have a GPS receiver.  

This document is consolidating, for the operator, a lot of regulations that are sprinkled about in other regulatory documents into one place.  So I don't know what your all getting excited about.  

 

PBN includes both the RNAV and RNP standards.  We don't have equipment that meets RNP, but we certainly do have equipment that meets RNAV.

If the author's reading is correct, it will clarify a couple things and it seems to pretty much say you can fly everything except the final approach course via appropriate GPS, including procedure turns, arcs and whatnot, even if those are based on localizers.

The other practical change would be to give you more airports to file as alternates.

[Mooney Dog]

28 minutes ago, tony said:

This document is for conducting  Performance-based Navigation (PBN) operations.  That's a concept that specifies the availability and an accuracy of the nav solution. These systems are what's required to fly in RNP airspace. It requires a DO-236 FMS.   We don't have that equipment in our little bug smashers.  we just have a GPS receiver.  

This document is consolidating, for the operator, a lot of regulations that are sprinkled about in other regulatory documents into one place.  So I don't know what your all getting excited about.  

 

RAIM is a type of PBN, which i know the 400/500 GNS units had. All new WAAS units have it as well. New GPS units are incredible accurate. There was a point in time, and still is for some aircraft, that a 91 GA bug smasher can shoot a lower approach than a 121 jet. 

 

And as the AC says, it applies to all 91, 91k, 135, and 121 operators. 

[Ragsf15e]

25 minutes ago, jaylw314 said:

PBN includes both the RNAV and RNP standards.  We don't have equipment that meets RNP, but we certainly do have equipment that meets RNAV.

If the author's reading is correct, it will clarify a couple things and it seems to pretty much say you can fly everything except the final approach course via appropriate GPS, including procedure turns, arcs and whatnot, even if those are based on localizers.

The other practical change would be to give you more airports to file as alternates.

We do have the required equipment to meet RNP (Required Navigation Performance) if we have an ifr gps.  We can’t fly RNP AR (Authorization Required) approaches, and some capabilities might be depending on your specific equipment ( like radius to fix legs which are in a gtn650/750 but not 430w).  The whole alphabet stew is very confusing…

AC 90-105A, published in March 2016, revises some of the terminology associated with RNAV and RNP procedures, in part to bring FAA conventions into agreement with ICAO standards associated with performance based navigation (PBN). The AC describes Required Navigation Performance Approach (RNP APCH) procedures, which you should not confuse with RNP ARprocedures. RNP APCH is essentially equivalent to RNAV (GPS). If you fly with an IFR-approved GPS, your aircraft meets the requirements to fly basic RNP APCH procedures as described in the AC. But you can’t fly RNP AR procedures unless you also meet the requirements of AC 90-101A.

[tony]

I don't think you guys understand.  Go look at all the approaches into Atlanta

https://www.airnav.com/airport/KATL

we can fly the RNAV (GPS) approaches but we can not fly the RNAV (RNP) approaches. 

the RNAV (GPS) approaches are not PBN

[Mooney Dog]

10 minutes ago, tony said:

I don't think you guys understand.  Go look at all the approaches into Atlanta

https://www.airnav.com/airport/KATL

we can fly the RNAV (GPS) approaches but we can not fly the RNAV (RNP) approaches. 

the RNAV (GPS) approaches are not PBN

From the document linked above.

"Note 2: This AC does not apply to Required Navigation Performance Authorization Required Approach (RNP AR APCH) approaches, titled “RNAV (RNP)” (ICAO: RNP RWY xx (AR))."

RNP AP and RNP more commonly known as GPS in the US, are different. 

To further go into this, If you want to fly Q or T routes, you have to have PBN GPS on your aircraft, and i know the GNS375 is a b2, c2. d2 for my aircraft. 

Edited August 14, 2021 by Mooney Dog

[kortopates]

38 minutes ago, tony said:

I don't think you guys understand.  Go look at all the approaches into Atlanta

https://www.airnav.com/airport/KATL

we can fly the RNAV (GPS) approaches but we can not fly the RNAV (RNP) approaches. 

the RNAV (GPS) approaches are not PBN

Actually you may be getting bogged down in the tetminology - its true in this country that virtualy every approach that has RNP in the title is an "RNP AR APPH" that we can't fly. But the whole point of this updates is to bring our teminology closer to the ICAO standard, and from the document:

"RNP APCH is not the same as the authorization required to comply with the RNP AR APCH standard. In the U.S. approaches that require the RNP AR APCH standard are titled RNAV (RNP) RWY xx."

Most importantly RNP approaches are not limited to the approaches that have RNP in the title, the RNAV GPS approaches are also RNP approach that are not RNP AR:

"In the United States, RNP APCH applies to all approach applications based on Global Positioning System (GPS), normally titled “RNAV (GPS)” or with “or GPS” in the title. These procedures provide operators one or more lines of minima (i.e., LNAV, LNAV/VNAV, LPV, or LP)…The RNP APCH NavSpec is intended to encompass all segments of the terminal approach operation: initial, intermediate, final, and missed approach…Charts for RNP APCH procedures will prominently display a standardized PBN Notes Box containing the procedure’s requirements including NavSpec(s) and, if needed, any required sensors or additional functionality (e.g., RF capability), as well as any minimum RNP value required for the procedure, and applicable remarks."

Outside of the US you'll see examples of RNP in the title, that allow GPS as means of meeting RNP 0.3 requirements without being AR - this has been the ICAO standard that we have been differing from.  

[kortopates]

As for an LPV  becoming a Precison Approach there is really nothing of practical importance new here, other than updating  some new terminolgy.

We've always been able to log LPV approaches as a Precision Approach (PA), if minimums where no higher than 250 agl, per the Instrument  ACS. The fact it wasn't technically a Precision approach was simply because the definition defined a precision approach based on terrestrial lateral and vertical nav (glide slope), till now. But so what.

I am sure they're not changing the key difference between a precision approach (ILS) and LPV approach - that for planning your required alternate airport, weather requirements for a GPS approach has to based on meeting a non-precision GPS approach (i..e allowing for the loss of WAAS), rather than another precision GPS approach (LPV minimums).

Maybe the terminology change will be easier for new IFR students, allowimng a LPV and PAR approaches to called a precision approach, but the differences between these and other Precision approach will still remain: Alternate requirements for the LPV and the PAR approach won't count in your required 6 approaches because it doesn't include "Intercepting and tracking courses".

So nothing new here other than changes to terminology including I guess we can drop the while APV category - which wasn't well understood.

Edited August 14, 2021 by kortopates

[tony]

Paul, agree with your assessment.  the FAA started this mess years ago when RNP meant both required navigation precision (GPS approach)  and Required Navigation Performance.  They are vastly different.    I'm sorry I said anything now. This AC was written for the big boys who have the money to install a DO-236 FMS with RNP.  I don't see the value to us.  

[kortopates]

4 minutes ago, tony said:

Paul, agree with your assessment.  the FAA started this mess years ago when RNP meant both required navigation precision (GPS approach)  and Required Navigation Performance.  They are vastly different.    I'm sorry I said anything now. This AC was written for the big boys who have the money to install a DO-236 FMS with RNP.  I don't see the value to us.  

Thanks Tony, absolutely. But although I am still digesting this, it looks like their consolidating everything RNAV into one PBN based document that includes approaches, terminal, enroute and oceanic - incuding everything for us and the RNP AR airline approaches. Its a 117 pages of very technical material!! As you point out how we have different users, I am not sure everything in one document is simplifying things.  

[jaylw314]

2 hours ago, kortopates said:

I am sure they're not changing the key difference between a precision approach (ILS) and LPV approach - that for planning your required alternate airport, weather requirements for a GPS approach has to based on meeting a non-precision GPS approach (i..e allowing for the loss of WAAS), rather than another precision GPS approach (LPV minimums).

Maybe the terminology change will be easier for new IFR students, allowimng a LPV and PAR approaches to called a precision approach, but the differences between these and other Precision approach will still remain: Alternate requirements for the LPV and the PAR approach won't count in your required 6 approaches because it doesn't include "Intercepting and tracking courses".

Well shucks, I guess that won't be to useful

Wait, a PAR doesn't count as a precision approach?  Not that I've ever done one, of course...

[kortopates]

Well shucks, I guess that won't be to useful
Wait, a PAR doesn't count as a precision approach?  Not that I've ever done one, of course...

No exactly, it doesn't count with respect to the 6 required approaches in the last 6 months as mentioned above.


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[jaylw314]

6 minutes ago, kortopates said:

No exactly, it doesn't count with respect to the 6 required approaches in the last 6 months as mentioned above.


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Wait, what?  I thought the "intercepting and tracking courses" was a wholly separate requirement from the "6 approaches"?  I mean, you don't have to do "holding procedures and tasks" during every approach for it to count as well, right?

[EricJ]

15 hours ago, PT20J said:

Probably a necessary precursor to eliminating more ILS installations.

I think many ILS approaches are protected along with the MON (minimum operational network) stuff.   DVT, my home field, has been getting a lot of improvements, including relocation of one the main taxiways, in order to bring it up to spec to get an ILS installed as a new addition.    We have two LPV approaches now, but they're investing a bunch to add the ILS.

[kortopates]

I see I didn't word that right. Your right that if you do a PAR/ASR you could also go beyond vectors to do some navigating. But logging intercepting and tracking is redundant with logging any approach other than a radar approach or a visual approach.


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[tony]

12 hours ago, Mooney Dog said:

RAIM is a type of PBN, which i know the 400/500 GNS units had. All new WAAS units have it as well. New GPS units are incredible accurate. There was a point in time, and still is for some aircraft, that a 91 GA bug smasher can shoot a lower approach than a 121 jet. 

 

And as the AC says, it applies to all 91, 91k, 135, and 121 operators. 

This document describes PBN.  Your Garmin is not capable of PBN

https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_90-105A.pdf

 

[Mooney Dog]

26 minutes ago, tony said:

This document describes PBN.  Your Garmin is not capable of PBN

https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_90-105A.pdf

 

From the ICAO filing codes. As it says, if you're planning to fly an RNAV arrival or departure, you have to have BPN. Im pretty sure my garmin can fly those.

Here's a page out of the garmin AFMS for the GPS 175 and GNC 355/375 systems. They can be installed in class 2 aircraft which absolutely meet the requirement for PBN. 

Furthermore, your document doesnt say anywhere that a part 91 operator cant use PBN, or that we're excluded. It just says the GPS unit has to comply with certain standards which my Garmin unit absolutely does. It says so right in the AFMS

11 hours ago, kortopates said:

that for planning your required alternate airport, weather requirements for a GPS approach has to based on meeting a non-precision GPS approach (i..e allowing for the loss of WAAS), rather than another precision GPS approach (LPV minimums).

I was under the assumption this was largely due to the fact GPS was never considered a precision approach. This document making a change where the FAA now say it IS a precision approach could very well change that rule on alternate airports. 

Edited August 14, 2021 by Mooney Dog

[ShuRugal]

.  Kind of reminds me of Texas slowly relying more and more on wind generators and solar power to only find out in an ice storm the wind generators freeze up and snow covers the solar panels.

It's interesting how nobody seemed to notice that while ERCOT had ~15 GW of wind generation knocked out by the storm, they had over 30 GW of thermal generation offline as well, including some nuclear capacity, because of things like pumps freezing solid.

It's almost like their problem was a failure to winterize the equipment, not the category of generation they were using.

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