LPV DA

Chief Captain

Chief Captain

Well-Known Member
Having a brain fart here gents.

From AIM 1-1-20
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b. Instrument Approach Capabilities
1. A new class of approach procedures which provide vertical guidance, but which do not meet the ICAO Annex 10 requirements for precision approaches has been developed to support satellite navigation use for aviation applications worldwide. These new procedures called Approach with Vertical Guidance (APV), are defined in ICAO Annex 6, and include approaches such as the LNAV/VNAV procedures presently being flown with barometric vertical navigation (Baro-VNAV).
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My highlight....An LPV approach is not technically considered a precision approach. Why do the FAA charts list LPV mins as a DA? My understanding was that DA's were reserved for precision approaches. What am I missing at 3am?
 
I always understood that nonprecision = MDA and precision = DA.

Are you saying that any approach with vertical guidance will automatically have a DA? If so, do you have a reference for that?
 
Found this from the FAA... LINK

Perhaps this summary will make it easier. Every IFR-certified and installed GPS unit allows the pilot to descend to LNAV (or Straight-in) and circling approaches. Baro-VNAV-equipped GPS systems can also descend to LNAV/VNAV minima. WAAS receivers can descend to LNAV, LNAV/VNAV, and LPV minima. Need another hint? Look for the DA designation versus the Minimum Descent Altitude (MDA) abbreviation on the minima line. Only procedures with vertical guidance have DAs. A descent angle may be provided on procedures which have only LNAV minima, to aid in a stabilized descent, but the MDA must still be respected.

Edit to Add: Here's a JC discussion from 2010 on this topic.
 
Not meeting the requirements of ICAO Annex 10 doesn't mean you have to treat it as an MDA. It means just that: It's not recognized by ICAO as a type of precision approach. Its lack of inclusion doesn't prohibit you from anything.
 
It's my opinion, after having dealt with the FAA a tiny bit on this issue, that the FAA hasn't quite figured out what to do with this stuff yet, and this is an example of technology outstripping the pace of regulation. When I once told a POI that his boys down in OK City had certified GPS approaches with a DA as the MAP, he was adamant that they hadn't. He was convinced that if an approach has a DA, that it's a precision approach, and that no GPS approaches are precision approaches, so it's not possible for a GPS approach to have a DA, because that would make it a precision approach.

I don't blame the guy for not being up on things, because again, I think technology has simply moved faster than the FAA is used to, and we're trying to fit these new approaches into old categories, and we, as an industry, won't always get it right or consistent.
 
dasleben said:
Not meeting the requirements of ICAO Annex 10 doesn't mean you have to treat it as an MDA. It means just that: It's not recognized by ICAO as a type of precision approach. Its lack of inclusion doesn't prohibit you from anything.
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It's defiitional, not operational.
 
jtrain609 said:
It's my opinion, after having dealt with the FAA a tiny bit on this issue, that the FAA hasn't quite figured out what to do with this stuff yet, and this is an example of technology outstripping the pace of regulation. When I once told a POI that his boys down in OK City had certified GPS approaches with a DA as the MAP, he was adamant that they hadn't. He was convinced that if an approach has a DA, that it's a precision approach, and that no GPS approaches are precision approaches, so it's not possible for a GPS approach to have a DA, because that would make it a precision approach.
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That's the next issue I'm going to. Where's the MAP on LPV approaches? If we're using LNAV mins, the runway is usually the MAP. On the LPV app, if the MAP is the DA, it's starting to sound a lot like a precision approach.
 
Chief Captain said:
That's the next issue I'm going to. Where's the MAP on LPV approaches? If we're using LNAV mins, the runway is usually the MAP. On the LPV app, if the MAP is the DA, it's starting to sound a lot like a precision approach.
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Just think of it as a nomenclature issue. Treat it like a precision approach, just know it doesn't meet standards to be called precision.
 
The IPC guidance allows the use of LPV to meet the precision approach requirement. Our FSDO also requires a LPV on the .297 rides, substituting the 2 non precision approaches is not allowed. So I am going with its a precision approach.
 
mojo6911 said:
Just think of it as a nomenclature issue. Treat it like a precision approach, just know it doesn't meet standards to be called precision.
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Operationally, I treat it as a PA. I was just looking for some clarification so that when I teach GPS approaches, I don't misinform the student. Law of primacy and all...

On a tangent, is the vertical guidance on an LPV considered advisory? Can you still do a "dive and drive" approach if you have LPV?
 
Could the DA just be used for an approach with vertical guidance but doesn't necessarilymean its a precision approach?
 
Chief Captain said:
Operationally, I treat it as a PA. I was just looking for some clarification so that when I teach GPS approaches, I don't misinform the student. Law of primacy and all...

On a tangent, is the vertical guidance on an LPV considered advisory? Can you still do a "dive and drive" approach if you have LPV?
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Would you dive and drive on an ILS? Why would you want to do it with a LPV?
 
If the vertical guidance is advisory in nature, I could see an argument for it, hence my question. I've never done it, but I spoke to somebody recently who told me he was taught to step down on the LPV. The only way I could see this being correct is if the vertical guidance is advisory.

Seems silly to me, because it negates the benefit of the LPV, but legal and logical are sometimes mutually exclusive...
 
On a LPV the vertical guidance is not advisory, it is treated exactly the same as a ILS. Also diving and driving down from the the last LNAV altitude to the LPV DA is a good way to hit things. If the GPS downgrades, then its back to dive and drive on the LNAV mins line, if there is one. Garmins will display the LNAV+V flag on some approaches, here the vertical is advisory and a dive and drive is ok, its not the same as the LNAV/VNAV min line which requires a BARO VNAV approved system.
 
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