LPV is it precison or non-precision

[poadeleted20]

So I have to have 800-2 to use it as an alternate but can fly it to posted mins of 225-1 when I get there?

800-2 or as otherwise published to file it (be sure to check for the /A\ symbol), yes, but that's only for filing purposes. After that, it's published mins.

One assumes, of course, that you have a WAAS c146 GPS; if you only have a non-WAAS c129 box, you can't file as an alternate any approach for which you'd have to use your GPS. That includes not only approaches with GPS in the title (unless it's a "XXX or GPS" approach, and you have the XXX box in your plane) but also if you need GPS to sub for DME or ADF to fly the approach.

 

[Henning]

Sorry, Ron... I fell into TWO classic traps here:

1) The resurrected old post (didn't notice the date);
2) Replying before reading the entire thread.

You'd think I'd learn...

Yah - I missed the age of the original thread.

Necroposting seems to bring up this issue on a pretty regular basis. Is there any way to get the system to pop you a warning that the post you're about to reply to was dead for over say, 6 months? I know I've been caught by it more than once.

 

[John Collins]

Was looking for the statement that if you have WAAS, you don't need to meet the requirement of choosing an alternate airport that has something other than GPS approaches. Still haven't found it specifically stated that way, but since WAAS is allowable as single-source navigation, it makes sense - as long as you only plan on using the LNAV altitudes.

Joe,

I haven't found a direct quotation, but the AFMS for the 430W with software prior to version 3.0 or with antenna limitations have a limitation that the alternate airport must have an alternate means other than a GPS approach that satisfy the alternate requirement. The AFMS after version 3.0 no longer has the limitation included.

 

[jmaynard]

If by "flight check" you mean an instrument practical test or IPC, they don't. Gotta be an ILS unless you have one of the two airplanes in the US equipped with MLS and you're at one of the two airports in the US with MLS approaches.

The last time I looked at the approach inventory summary, it listed 0 MLS approaches. Did they decommission them?

 

[Henning]

The last time I looked at the approach inventory summary, it listed 0 MLS approaches. Did they decommission them?

I would expect so. DGPS was coming on line at the same time as MLS, and that was during the budget crunching 80s. MLS probably lost its funding.

 

[joemurffy]

Joe,

I haven't found a direct quotation, but the AFMS for the 430W with software prior to version 3.0 or with antenna limitations have a limitation that the alternate airport must have an alternate means other than a GPS approach that satisfy the alternate requirement. The AFMS after version 3.0 no longer has the limitation included.

John,

Thanks for getting back to me on the only real question I had from my post. Concerning all of the other questions about the three types of approaches (PA, APV, and NPA), I think I gave all of the salient references. And I am truly sorry to all about resurrecting a post that petered out several months ago.

John, concerning the question of being able to chose an alternate that has nothing other than GPS approaches if you're flying with IFR approved WAAS avionics, here is what I was remembering. This comes from the AIM, Section 1-1-20, c.7.(a).

Pilots with WAAS receivers may flight plan to use any instrument approach procedure authorized for use with their WAAS avionics as the planned approach at a required alternate, with the following restrictions.​

I'll let you read the rest, but this only makes sense since, "WAAS avionics are evaluated without reliance on other navigation systems. As such, installation of WASS avionics does not require the aircraft to have other equipment appropriate to the route to be flown." (from the paragraph immediately preceding the one quoted, above.)

 

[Bob Noel]

well, MLS siting requirements are much easier, so the total cost to install the ground equipment can be much less expensive than ILS, not to mention the less restrictive siting requirements.

 

[Bob Noel]

> As far as MLS being lost... thank Reagan.

huh? President Reagan had zippo with MLS being "lost"... unless he could make those decisions years after he left office.

 

[poadeleted20]

well, MLS siting requirements are much easier, so the total cost to install the ground equipment can be much less expensive than ILS, not to mention the less restrictive siting requirements.

Perhaps, but GPS has zero siting costs/restrictions.

 

[Bob Noel]

> but GPS has zero siting costs/restrictions.

I was not aware that WAAS and LAAS ground components had no siting costs or restrictions.

 

[poadeleted20]

> but GPS has zero siting costs/restrictions.

I was not aware that WAAS and LAAS ground components had no siting costs or restrictions.

There are no added local ground components needed for a WAAS approach, and the WAAS ground stations are already set up and running, so there's no new infrastructure at the airport getting the WAAS approach as there is with ILS or MLS, and no local operating expenses. The rest of the costs associated with establishing an approach (designing the SIAP, surveying the airport, etc) are pretty much the same for all systems. As for LAAS, yes, there are new equipment costs, but it ain't happening yet, you get near-ILS performance with only WAAS, and you don't need LAAS for LPV capability. In any event, MLS is dead and GPS is still growing.

 

[gismo]

There are no added local ground components needed for a WAAS approach, and the WAAS ground stations are already set up and running, so there's no new infrastructure at the airport getting the WAAS approach as there is with ILS or MLS, and no local operating expenses. The rest of the costs associated with establishing an approach (designing the SIAP, surveying the airport, etc) are pretty much the same for all systems. As for LAAS, yes, there are new equipment costs, but it ain't happening yet, you get near-ILS performance with only WAAS, and you don't need LAAS for LPV capability. In any event, MLS is dead and GPS is still growing.

There doesn't have to be, but there can be local infrastructure required for WAAS approaches, particularly those with ILS like minimums. The extra stuff needed would be approach lighting, pavement markings, etc. Not necessarily in the same league as a full blown ILS install but not all that cheap either.

 

[John Collins]

There are no added local ground components needed for a WAAS approach, and the WAAS ground stations are already set up and running, so there's no new infrastructure at the airport getting the WAAS approach as there is with ILS or MLS, and no local operating expenses. The rest of the costs associated with establishing an approach (designing the SIAP, surveying the airport, etc) are pretty much the same for all systems. As for LAAS, yes, there are new equipment costs, but it ain't happening yet, you get near-ILS performance with only WAAS, and you don't need LAAS for LPV capability. In any event, MLS is dead and GPS is still growing.

I understand what you mean, that there is no local ground based navigation equipment required for a WAAS based approach, but as Lance pointed out there are other infrastructure expenses that can be required to be added to get the lowest possible minimums. Examples are the approach lighting systems, runway length, runway markings, taxiways, etc. All of these require on going maintenance as well. So far, when there is an ILS already in use to a runway, the WAAS approach doesn't add to these type of expenses, and this is more the norm.

 

[John Collins]

Yes, there is, but I don't know the exact details. However, you can get a rough idea by looking in Section 1 of the AIM for the basic tolerances for each type of approach (e.g., ILS GS about 90 feet thick vertically at the MM [1.4 degrees at 4000 feet distance from antenna] vs 35-50 meter maximum vertical error for LPV).

The Full Scale Deflection for an ILS is as you noted +/- .7 degrees. For an LPV, the FSD is +/- 25% of the glidepath angle, so for a 3 degree glidepath, it is +/- .75 degrees. They are for all practical purposes the same. The 35-50 meter value is an integrity limit equal to the 99.99999% probability that the vertical error is contained within limits. It should not be compared with the FSD value, but with the equivalent integrity limit for an ILS.

The ILS integrity can be affected by several factors, such as aircraft on or near the runway, snow on the antenna or on the ground, antenna position, and transmission/ modulation error. Additional error is introduced by the position of the antenna on the aircraft.

Regardless, both approaches have minimums that are based on the barometric altimeter and dependent on its accuracy and the correct barometer setting. In both cases, the terrain clearance takes into account the error budget both in the system and the on-board equipment.

One advantage of WAAS, is that it is continuously monitored whereas many ILS installations are not, particularly at non-towered airports or where the tower is shut down.

 

[poadeleted20]

I understand what you mean, that there is no local ground based navigation equipment required for a WAAS based approach, but as Lance pointed out there are other infrastructure expenses that can be required to be added to get the lowest possible minimums. Examples are the approach lighting systems, runway length, runway markings, taxiways, etc.

True, but those have to be done for any type of approach. I thought the question was the additional cost of MLS over GPS when putting in an approach at an airport without any approaches.

 

[Kameron]

So this thread is a decade old but I am curious, do we consider basically only ILS to be precision? I tried to look up the Annex 10 and that seemed like a disaster.

 

[aterpster]

So this thread is a decade old but I am curious, do we consider basically only ILS to be precision? I tried to look up the Annex 10 and that seemed like a disaster.

ILS and PAR. LPV is an approach with vertical guidance.

 

[tsts4]

But an LPV can be used on a Check ride or IPC to meet the precision approach requirements. Per the ACS "an LPV minimums approach can be used to demonstrate precision approach proficiency if the DA is equal to or less than 300 feet HAT."

 

[aterpster]

But an LPV can be used on a Check ride or IPC to meet the precision approach requirements. Per the ACS "an LPV minimums approach can be used to demonstrate precision approach proficiency if the DA is equal to or less than 300 feet HAT."

Indeed it can. That doesn't make it ICAO-compliant as a precision approach.

From the AIM:

Approach with Vertical Guidance (APV).
An instrument approach based on a navigation
system that is not required to meet the precision
approach standards of ICAO Annex 10 but provides
course and glidepath deviation information. For
example, Baro−VNAV, LDA with glidepath, LNAV/
VNAV and LPV are APV approaches.

 

[MauleSkinner]

But an LPV can be used on a Check ride or IPC to meet the precision approach requirements. Per the ACS "an LPV minimums approach can be used to demonstrate precision approach proficiency if the DA is equal to or less than 300 feet HAT."

Note, however, that the ACS doesn’t say it IS a precision approach...it can merely “be used to demonstrate precision approach proficiency”.

 

[tsts4]

Indeed it can. That doesn't make it ICAO-compliant as a precision approach.

From the AIM:

Approach with Vertical Guidance (APV).
An instrument approach based on a navigation
system that is not required to meet the precision
approach standards of ICAO Annex 10 but provides
course and glidepath deviation information. For
example, Baro−VNAV, LDA with glidepath, LNAV/
VNAV and LPV are APV approaches.

Note, however, that the ACS doesn’t say it IS a precision approach...it can merely “be used to demonstrate precision approach proficiency”.

Didn't state otherwise -- just pointed out what the ACS says which in essence is it can be a suitable sub for training and certification purposes in lieu of a precision approach (ILS or PAR), as defined by the FAA and ICAO. So outside of a test question, IMO for most of us the definition is basically irrelevant.

 

[MauleSkinner]

Didn't state otherwise -- just pointed out what the ACS says which in essence is it can be a suitable sub for training and certification purposes in lieu of a precision approach (ILS or PAR), as defined by the FAA and ICAO. So outside of a test question, IMO for most of us the definition is basically irrelevant.

Outside of alternate airport requirements, yes.