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PA28Rdrvr
October 27th 03, 02:05 AM
Hello. I see there are lots of smart folks in this NG and I learn a lot
from you. I have a question that I sure someone can answer for me. I'm not
so knowledgeable about some of the GPS approach procedures. I was reviewing
the GPS 16L @ KHEF (Manassas VA) and am not sure which DH is applicable to
my flying. I am not sure why the difference in LPV DA; LNAV/VNAV DA; and,
LNAV MDA. I fly a PA28R with a Garmin 430. Which landing minimum would
apply to me? Could someone expound on what each minimum applies to and the
decision process for determining which one applies to a particular aircraft?
I believe it is usually different types of on board equipment that would be
the determining factor but I do not know what is required for each. So far,
I have not been able to locate any educational reading that would explain it
for me.
Thanks in advance for your helpful comments.

John R. Copeland
October 27th 03, 02:38 AM
VNAV, LPV, and the future GLS give vertical guidance,
for "Near-Precision Approach" (like ILS) specifications, hence DH.

GPS and LNAV are non-precision, and therefore MDA is appropriate.
They are still based on "Dive and Drive".

Your Garmin 430 computes position updates only once per second,
so it can be certified only under TSO-C129.
Your G-430 GPS approaches are restricted to non-precision.

You would need a TSO-C145 or TSO-C146 unit for precision approaches.
Those units must update their positions five times per second.

I am undergoing a CNX-80/MX-20 installation at this exact moment.
I hope to learn a lot more about this topic in the very near future.
---JRC---

"PA28Rdrvr" > wrote in message =
...
> Hello. I see there are lots of smart folks in this NG and I learn a =
lot
> from you. I have a question that I sure someone can answer for me. =
I'm not
> so knowledgeable about some of the GPS approach procedures. I was =
reviewing
> the GPS 16L @ KHEF (Manassas VA) and am not sure which DH is =
applicable to
> my flying. I am not sure why the difference in LPV DA; LNAV/VNAV DA; =
and,
> LNAV MDA. I fly a PA28R with a Garmin 430. Which landing minimum =
would
> apply to me? Could someone expound on what each minimum applies to =
and the
> decision process for determining which one applies to a particular =
aircraft?
> I believe it is usually different types of on board equipment that =
would be
> the determining factor but I do not know what is required for each. =
So far,
> I have not been able to locate any educational reading that would =
explain it
> for me.
> Thanks in advance for your helpful comments.
>=20
>

October 27th 03, 02:35 PM
No one has LPV yet. That is near-precision and requires WAAS and a fast-update
receiver.

VNAV does not require WASS but does require IFR-certified Baro VNAV displayed on
a glideslope indicator. The Garmin 400/500 VNAV function is not IFR-certified
Baro VNAV.

So, you are limited to LNAV minimums...strictly non-precision no different than
any ground-based non-precision approach procedure.

PA28Rdrvr wrote:

> Hello. I see there are lots of smart folks in this NG and I learn a lot
> from you. I have a question that I sure someone can answer for me. I'm not
> so knowledgeable about some of the GPS approach procedures. I was reviewing
> the GPS 16L @ KHEF (Manassas VA) and am not sure which DH is applicable to
> my flying. I am not sure why the difference in LPV DA; LNAV/VNAV DA; and,
> LNAV MDA. I fly a PA28R with a Garmin 430. Which landing minimum would
> apply to me? Could someone expound on what each minimum applies to and the
> decision process for determining which one applies to a particular aircraft?
> I believe it is usually different types of on board equipment that would be
> the determining factor but I do not know what is required for each. So far,
> I have not been able to locate any educational reading that would explain it
> for me.
> Thanks in advance for your helpful comments.

Snowbird
October 27th 03, 03:08 PM
"PA28Rdrvr" > wrote in message >...
> Hello. I see there are lots of smart folks in this NG and I learn a lot
> from you. I have a question that I sure someone can answer for me. I'm not
> so knowledgeable about some of the GPS approach procedures. I was reviewing
> the GPS 16L @ KHEF (Manassas VA) and am not sure which DH is applicable to
> my flying.

Well, let's stop right there.

"DH" is for precision approaches, where the nav you are using provides
vertical guidance.

Are you getting vertical guidance? No. So DH doesn't apply to you,
and you want an MDA, just like if you're flying an ILS approach w/out
glideslope. DH doesn't apply to you, you use the LOC MDA.

> I am not sure why the difference in LPV DA; LNAV/VNAV DA; and,
> LNAV MDA. I fly a PA28R with a Garmin 430. Which landing minimum would
> apply to me?

LNAV MDA.

> I believe it is usually different types of on board equipment

Exactly. You need an IFR GPS which is WAAS capable and a glideslope
to fly a VNAV or LPV approach.

HTH,
Sydney

October 27th 03, 03:33 PM
Snowbird wrote:

> Exactly. You need an IFR GPS which is WAAS capable and a glideslope
> to fly a VNAV or LPV approach.
>

And, those are two very different types of glideslopes, from an equippage standpoint.

Eddie
October 27th 03, 07:09 PM
> Snowbird wrote:
>
> > Exactly. You need an IFR GPS which is WAAS capable and a glideslope
> > to fly a VNAV or LPV approach.
> >
>
> And, those are two very different types of glideslopes, from an equippage
standpoint.
>

and because of that we should all start using the term 'vertical guidance' -
a glideslope is part of an ILS

John R. Copeland
October 27th 03, 09:53 PM
"Eddie" > wrote in message =
.. .
> > Snowbird wrote:
> >
> > > Exactly. You need an IFR GPS which is WAAS capable and a =
glideslope
> > > to fly a VNAV or LPV approach.
> > >
> >
> > And, those are two very different types of glideslopes, from an =
equippage
> standpoint.
> >
>=20
> and because of that we should all start using the term 'vertical =
guidance' -
> a glideslope is part of an ILS
>=20
>=20

I suppose the term "glideslope" will persist in the future as a generic =
term.
Even the Pilot/Controller Glossary with the AIM doesn't restrict it to =
ILS.
It mentions the ILS glideslope as just one example of "vertical guidance
for aircraft during approach and landing".
---JRC---

PA28Rdrvr
October 28th 03, 01:26 AM
Thank you all very much. I understand the difference now.

"John R. Copeland" > wrote in message
...

"Eddie" > wrote in message
.. .
> > Snowbird wrote:
> >
> > > Exactly. You need an IFR GPS which is WAAS capable and a glideslope
> > > to fly a VNAV or LPV approach.
> > >
> >
> > And, those are two very different types of glideslopes, from an
equippage
> standpoint.
> >
>
> and because of that we should all start using the term 'vertical
guidance' -
> a glideslope is part of an ILS
>
>

I suppose the term "glideslope" will persist in the future as a generic
term.
Even the Pilot/Controller Glossary with the AIM doesn't restrict it to ILS.
It mentions the ILS glideslope as just one example of "vertical guidance
for aircraft during approach and landing".
---JRC---

October 28th 03, 10:14 AM
"John R. Copeland" wrote:

>
>
> I suppose the term "glideslope" will persist in the future as a generic term.
> Even the Pilot/Controller Glossary with the AIM doesn't restrict it to ILS.
> It mentions the ILS glideslope as just one example of "vertical guidance
> for aircraft during approach and landing".
> ---JRC---

The term used by FAA TERPs developers for Baro VNAV, LPV, and GLS, is "glidepath."

John R. Copeland
October 28th 03, 04:28 PM
> wrote in message =
...
>=20
>=20
> "John R. Copeland" wrote:
>=20
> >
> >
> > I suppose the term "glideslope" will persist in the future as a =
generic term.
> > Even the Pilot/Controller Glossary with the AIM doesn't restrict it =
to ILS.
> > It mentions the ILS glideslope as just one example of "vertical =
guidance
> > for aircraft during approach and landing".
> > ---JRC---
>=20
> The term used by FAA TERPs developers for Baro VNAV, LPV, and GLS, is =
"glidepath."
>=20

My Pilot/Controller Glossary says "GLIDEPATH - (See GLIDESLOPE.)"
That probably means "Use either word" for now.
Time will tell if one term wins out over the other.

Interestingly, the P/CG shows a definition for "GLIDEPATH [ICAO]".
Maybe a Glidepath is a *metric* Glideslope. :-)
---JRC---

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