GPS approaches with VNAV vertical guidance

With all the talk about the GNS80 and the Garmin 430 having VNAV and
LAAS capability, I would like to know something. Are there any actual
approaches in use that one can fly, today, that use these features? Do
you get vertical guidance from GPS derived altitude or is it vertical
guidance from altimeter derived altitude? Where are these approaches?

In article ,
(Doug) wrote:

With all the talk about the GNS80 and the Garmin 430 having VNAV and
LAAS capability, I would like to know something. Are there any actual
approaches in use that one can fly, today, that use these features? Do
you get vertical guidance from GPS derived altitude or is it vertical
guidance from altimeter derived altitude? Where are these approaches?

The GPS-16 at HPN has both LNAV and LNAV/VNAV minimums published. LNAV
alone gets you 600 & 1, VNAV gets you another 120 feet lower.

What's a little silly is that there's also an ILS-16 which gets you the
standard 200 & 1/2, so except as a contingency against the ILS being
OTS, having the LNAV/VNAV approach doesn't buy you anything. The big
payoff is still in the future, when the FAA starts publishing LNAV/VNAV
approaches to runway ends (and airports) which aren't already served by
ILS or other ground-based approaches.

I havn't actually flown a VNAV approach yet. When we get our CNX-80's
upgraded to the new software (RSN), I'll be able to try it out.

Roy Smith wrote:

In article ,
(Doug) wrote:

With all the talk about the GNS80 and the Garmin 430 having VNAV and
LAAS capability, I would like to know something. Are there any actual
approaches in use that one can fly, today, that use these features? Do
you get vertical guidance from GPS derived altitude or is it vertical
guidance from altimeter derived altitude? Where are these approaches?

The GPS-16 at HPN has both LNAV and LNAV/VNAV minimums published. LNAV
alone gets you 600 & 1, VNAV gets you another 120 feet lower.

What's a little silly is that there's also an ILS-16 which gets you the
standard 200 & 1/2, so except as a contingency against the ILS being
OTS, having the LNAV/VNAV approach doesn't buy you anything. The big
payoff is still in the future, when the FAA starts publishing LNAV/VNAV
approaches to runway ends (and airports) which aren't already served by
ILS or other ground-based approaches.

I havn't actually flown a VNAV approach yet. When we get our CNX-80's
upgraded to the new software (RSN), I'll be able to try it out.

Once it works, I believe your advantage with be with LPV minimums more than
VNAV/LNAV minimums.

"Roy Smith" wrote in message
...

What's a little silly is that there's also an ILS-16 which gets you the
standard 200 & 1/2, so except as a contingency against the ILS being
OTS, having the LNAV/VNAV approach doesn't buy you anything.

There's significant labor involved in charting a new approach- obstacle
analysis, airspace planning, test-flying, etc. My guess is that where there
is an ILS already, creating an LNAV/VNAV approach is relatively low-cost
since you can piggyback on most of the existing labor.

Likewise, I suspect most of the new approaches we'll see over the next year
or two will be added to fields already equipped with an ILS. Lots of fields
here in the Northeast have an ILS but only on one runway end. I suspect in
five years or so every airport with air carrier traffic will have a
precision approach to every runway end. Somewhere along the way, we'll start
to see a trickle of these come to fields that currently have published
approaches but no ILS.

Another issue is that right now only airlines can really make use of this
stuff anyway, since relatively few people are flying behind v2 GNS-480s.
This is why Jane Garvey said in her AOPA speech that it's important for
pilots to go out and get new equipment that can make use of this. Of course,
I'd like to see her agency help by making it easier to certify and install
such equipment. There's no reason it should cost $15,000 to do so.

-cwk.

wrote:
Once it works, I believe your advantage with be with LPV minimums more than
VNAV/LNAV minimums.

The plate shows a catagory of "GLS PA DA", which I decode as "GPS
Landing System, Precision Approach, Decision Altitude" (with minimums
shown as NA). Is that the same as the LPV you're talking about?

Roy Smith wrote:
wrote:

Once it works, I believe your advantage with be with LPV minimums more than
VNAV/LNAV minimums.


The plate shows a catagory of "GLS PA DA", which I decode as "GPS
Landing System, Precision Approach, Decision Altitude" (with minimums
shown as NA). Is that the same as the LPV you're talking about?

Take a look at RNAV(GPS) RWY 36 at OSH for an example of an approach with
different LPV, VNAV, and LNAV minima.

Dave

The plate shows a catagory of "GLS PA DA", which I decode as "GPS
Landing System, Precision Approach, Decision Altitude" (with minimums
shown as NA). Is that the same as the LPV you're talking about?

GLS does stand for "GPS Landing System," and would provide capability
equivalent to CAT I ILS (200 ft decision height/altitude). WAAS was
originally supposed to provide this, but due to integrity issues is only good
down to 250 ft, which is the limit for LPV approaches. Current plans for WAAS
upgrades include better coverage and redundancy, but not GLS. There are
tentative plans to modernize GPS and add a new civil frequency; if this is
done, then WAAS might provide GLS at some time after 2013.

(Doug) wrote in message om...
With all the talk about the GNS80 and the Garmin 430 having VNAV and
LAAS capability, I would like to know something. Are there any actual
approaches in use that one can fly, today, that use these features? Do
you get vertical guidance from GPS derived altitude or is it vertical
guidance from altimeter derived altitude? Where are these approaches?

Doug,

I assume you meant WAAS, not LAAS. I'm showing 261 WAAS VNAV
approaches as of August 5th update cycle. 237 are LNAV/VNAV minima and
24 are LPV minima. AVN's Website has good info:

http://www.avn.faa.gov/index.asp?xml=index

Regards,
Jon

"Roy Smith" wrote in message
...
In article ,
(Doug) wrote:

What's a little silly is that there's also an ILS-16 which gets you the
standard 200 & 1/2, so except as a contingency against the ILS being
OTS, having the LNAV/VNAV approach doesn't buy you anything. The big
payoff is still in the future, when the FAA starts publishing LNAV/VNAV
approaches to runway ends (and airports) which aren't already served by
ILS or other ground-based approaches.


Our local "big" airport has four ILS's to 200 ft DH, and various VOR, GPS,
and NDB approaches. There are four new RNAV(GPS) approaches: for each
runway (36L and 36R), there are two of these approaches (Y and Z). In each
case, Z has LNAV and LNAV/VNAV minima, and Y has LNAV only. The Y and Z
approaches have the same IAFs, IF, FAFs, and MAPs. The Z LNAV MDA is 545
ATDZE, the Z LNAV/VNAV MDA is 325 ATDZE, a 220 ft advantage. But on the Y
approach, the LNAV MDA is 325 ATDZE. The only difference between the
approaches is that Y has a stepdown fix after the FAF, which is apparently
avoided by VNAV. Heck, with a 325 ft ATDZE MDA with LNAV alone, I sure
don't need VNAV, if it just gets me to the same DA. And 325 is pretty darn
good.

It's curious to me that two approach plates were published for Y & Z, rather
then combining them and noting the stepdown fix as applicable to LNAV only.
Maybe it made for too much chart clutter.

I hope we get the corresponding approaches for 18L and 18R.

For a while, LNAV procedures with a stepdown were not allowed to be
combined with a LNAV/VNAV. If you wanted a stepdown to get lower LNAV
MDA, you had to create a separate procedure. That rule has since been
rescinded, so you'll see future combined LNAV/VNAV and LNAV with a
stepdown if appropriate. In the meantime, the "X" and "Y" procedures
will remain as they are until amended, but amending them is not a priority.

JPH

Stan Prevost wrote:
"Roy Smith" wrote in message
...


Our local "big" airport has four ILS's to 200 ft DH, and various VOR, GPS,
and NDB approaches. There are four new RNAV(GPS) approaches: for each
runway (36L and 36R), there are two of these approaches (Y and Z). In each
case, Z has LNAV and LNAV/VNAV minima, and Y has LNAV only. The Y and Z
approaches have the same IAFs, IF, FAFs, and MAPs. The Z LNAV MDA is 545
ATDZE, the Z LNAV/VNAV MDA is 325 ATDZE, a 220 ft advantage. But on the Y
approach, the LNAV MDA is 325 ATDZE. The only difference between the
approaches is that Y has a stepdown fix after the FAF, which is apparently
avoided by VNAV. Heck, with a 325 ft ATDZE MDA with LNAV alone, I sure
don't need VNAV, if it just gets me to the same DA. And 325 is pretty darn
good.

It's curious to me that two approach plates were published for Y & Z, rather
then combining them and noting the stepdown fix as applicable to LNAV only.
Maybe it made for too much chart clutter.

I hope we get the corresponding approaches for 18L and 18R.