Why is ADF required on ILS approach?

[Rich Raine]

Wait! He can use a GPS in place of the ADF on that approach. Isn't that
correct?

Rich Raine
www.eraine.com

And the ILS plate is marked ADF required? Why is that?

... because you need to know where the LOM/IAF called LADOS is.
It's an IAF, so there's no previous fix from which you can start timing to
find LADOS.
DME is not required, so you can't assume you can use it to find LADOS -

yes,

even though it's clearly marked 5.2NM on the plate.
If you want to get into ELD without an ADF, you'll have to use one of the
other 3 approaches. Those aren't terrible options.

[Thomas Borchert]

Gig,

the initial approach fix (IAF) is defined by the NDB. how would you
find this point without an ADF? You'd get around that with radar
vectors, but you couldn't fly the full procedure without the NDB. And
the missed approach is a hold on the NDB. Same problem.

BUT: An approach certified GPS with the NDB in it's database can
replace for the ADF.

[Gig Giacona]

Let's see if I have this straight and please forgive any ignorance on my
part.

When I got my PP-SEL in ELD '79-'80 there was no ILS or NDB approach at ELD
just VOR. All the pilots bitched including the Lear and Citation pilots and
their bosses and ELD gets an ILS. But it gets put in requireing ADF that
even then was on the way out.

This is the silliest thing I have ever heard of.

Post by Thomas Borchert
Gig,
the initial approach fix (IAF) is defined by the NDB. how would you
find this point without an ADF? You'd get around that with radar
vectors, but you couldn't fly the full procedure without the NDB. And
the missed approach is a hold on the NDB. Same problem.
BUT: An approach certified GPS with the NDB in it's database can
replace for the ADF.
--
Thomas Borchert (EDDH)

[Stan Prevost]

Post by Gig Giacona
Let's see if I have this straight and please forgive any ignorance on my
part.
When I got my PP-SEL in ELD '79-'80 there was no ILS or NDB approach at ELD
just VOR. All the pilots bitched including the Lear and Citation pilots and
their bosses and ELD gets an ILS. But it gets put in requireing ADF that
even then was on the way out.
This is the silliest thing I have ever heard of.

New NDBs are still being commissioned in the US.

Stan

[Leland Vandervort]

An instrument approach requires an IAF. In the case of an ILS
approach, this must be separate to the ILS localiser and glideslope
because of the directive nature of the aid. The most common solution
is to use an NDB to provide the IAF and base the procedure on that.
NDBs installed in conjunction with instrument approach aids are
generally lower power than en-route NDBs. You could, in theory, use a
VOR as the IAF as well, however. Also marker beacons are notorious
for going on the blink, so a co-located NDB with the outer marker
(called "LOC") provides an additional check for ranging on the final
approach. (in some cases, the ILS system might not even have marker
beacons, in which case an NDB will be required at the OM location).
Remember that not all ILS systems have DME associated, so some form of
range checking is required.

The vast majority of ILS approaches in Europe use an NDB as the IAF
and many of them use an NDB LOCator (colocated with outer marker).

My local airport has several instrument procedures: ILS/NDB, NDB
Only, VOR, and VDF. There is no DME on either the ILS or the VOR and
since the VOR is on the A/D and not 7.5 nautical miles out like the
NDB, it can't reasonably be used as the IAF for the ILS approach
without totally throwing totally non-standard timings into the
equation. (as it is already the VOR approach [non-precision] already
has a non-standard outbound timing to begin base turn).

You will find that even on some of the more advanced European
airports, there are NDBs associated with the ILS at the outer marker
location. (Heathrow, Gatwick, Stanstead, Luton, East Midlands,
Birmingham, Paris Orly, Paris Charles de Gaulle, all have NDB LOCs at
around 8 nautical miles out.).

Also most holding procedures in the Europe use NDBs as the holding
fix. (there are currently NO operationally published GPS approaches
in the UK, and the CAA and even JAA are tending to be somewhat wary of
implementing GPS procedures for instrument approaches.)

Regards,

Leland



On Wed, 9 Jul 2003 08:40:13 -0500, "Gig Giacona"

Post by Gig Giacona
Let's see if I have this straight and please forgive any ignorance on my
part.
When I got my PP-SEL in ELD '79-'80 there was no ILS or NDB approach at ELD
just VOR. All the pilots bitched including the Lear and Citation pilots and
their bosses and ELD gets an ILS. But it gets put in requireing ADF that
even then was on the way out.
This is the silliest thing I have ever heard of.

Post by Thomas Borchert
Gig,
the initial approach fix (IAF) is defined by the NDB. how would you
find this point without an ADF? You'd get around that with radar
vectors, but you couldn't fly the full procedure without the NDB. And
the missed approach is a hold on the NDB. Same problem.
BUT: An approach certified GPS with the NDB in it's database can
replace for the ADF.
--
Thomas Borchert (EDDH)

[David Brooks]

Post by Leland Vandervort
Also most holding procedures in the Europe use NDBs as the holding
fix. (there are currently NO operationally published GPS approaches
in the UK, and the CAA and even JAA are tending to be somewhat wary of
implementing GPS procedures for instrument approaches.)

Is there a single rationale for this wariness? The obviously compelling
reason is that other nations would be reluctant to throw the future of their
air navigation into the hands of a system controlled by the US military -
we're allies now, but alliances change within the lifespan of an
aeronautical system. Or is there something more mundane: the incremental
cost causing slow adoption, or the decision to put more INS systems into
European planes before GPS came along, or roll out MLS faster than the US,
or what?

-- David Brooks

[Tarver Engineering]

Post by David Brooks

Post by Leland Vandervort
Also most holding procedures in the Europe use NDBs as the holding
fix. (there are currently NO operationally published GPS approaches
in the UK, and the CAA and even JAA are tending to be somewhat wary of
implementing GPS procedures for instrument approaches.)

Is there a single rationale for this wariness?

No, as MLS airborne equipments use GPS derived DME.

Post by David Brooks
The obviously compelling
reason is that other nations would be reluctant to throw the future of their
air navigation into the hands of a system controlled by the US military -
we're allies now, but alliances change within the lifespan of an
aeronautical system.

The really compelling reason for building Galileo is to bridge a technology
gap, unfortunately TACAN stations interfere with the proposed Euro Nav
signal.

Post by David Brooks
Or is there something more mundane: the incremental
cost causing slow adoption, or the decision to put more INS systems into
European planes before GPS came along, or roll out MLS faster than the US,
or what?

Working MLS uses GPS, so the reasoning has to be somewhat convoluted. Then
again, if Galileo provides binary stars, the Europeans will be ahead of the
US in space based Navigation.

John P. Tarver, MS/PE

[David Megginson]

Post by Leland Vandervort
The vast majority of ILS approaches in Europe use an NDB as the IAF
and many of them use an NDB LOCator (colocated with outer marker).

Ditto for Canada: to my knowledge, we no longer have any marker
beacons at all. Every Canadian ILS approach I've seen so far has an
NDB as the IAF/FAF, but I'm sure that someone can point out an
exception somewhere.

I was surprised to see the marker lights on my audio panel light up,
one after the other, when I overflew Albany NY a few weeks ago -- I
had never seen them light up except with the test button, and even
turned on the audio just to hear what they sounded like.


All the best,


David

[Leland Vandervort]

On Thu, 10 Jul 2003 02:06:30 GMT, David Megginson

Post by David Megginson
I was surprised to see the marker lights on my audio panel light up,
one after the other, when I overflew Albany NY a few weeks ago -- I
had never seen them light up except with the test button, and even
turned on the audio just to hear what they sounded like.

S'okay.. at my base airfield we have OM and MM, but half the time they
don't work anyway...


di-dah-di-dah-di-dah-di-dah
dah-dah-dah-dah-dah
di-di-di-di-di-di-di

:)

Leland

[David Megginson]

Post by Leland Vandervort
di-dah-di-dah-di-dah-di-dah
dah-dah-dah-dah-dah
di-di-di-di-di-di-di

Thanks -- that would have saved me the whole trip over Albany. I
assume that you're using an appropriately high-pitched voice (it's
hard to tell by e-mail).


All the best,


David

[Ross Richardson]

That's correct and defines LADOS (the localizer and ELD 018/2miles) I
had a similar problem (before I got my certified GPS) for KGYI. Newly
commissioned ILS and it came out with a ADF REQUIRED on the plate. I
contacted the FAA and we discussed. I also submitted that the outer
marker (DNI) could be easily defined by the feeder route from BYP and
the localizer. I still do not understand the reason; must be something
in the TERPS.

Post by Thomas Borchert
the initial approach fix (IAF) is defined by the NDB. how would you
find this point without an ADF?

There is a feeder route from ELD to LADOS.

[Ron Rosenfeld]

Post by Ross Richardson
That's correct and defines LADOS (the localizer and ELD 018/2miles) I
had a similar problem (before I got my certified GPS) for KGYI. Newly
commissioned ILS and it came out with a ADF REQUIRED on the plate. I
contacted the FAA and we discussed. I also submitted that the outer
marker (DNI) could be easily defined by the feeder route from BYP and
the localizer. I still do not understand the reason; must be something
in the TERPS.

I believe it has something to do with a concept called "positive course
guidance".


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

[jay somerset]

On Tue, 8 Jul 2003 14:18:55 -0500, "Gig Giacona"

I've not been flying in a while and don't have an IR. But I plan to get one
as soon after I finish building my plane.
I was looking at this approach plate for my home field
http://www.myairplane.com/databases/approach/SouthCentral/ELD_ir22.pdf
or http://tinyurl.com/gcjc
And the ILS plate is marked ADF required? Why is that?
PPSEL R-H
My Zodiac 601XL
www.peoamerica.net/N601WR

Two reasons -- the (one and only) IAF is defined by the LOM, and that
is also the missed approach fix. An ILS approach still has the missed
approach as a integral segment.

[Steven P. McNicoll]

It's an IAF, so there's no previous fix from which you can start timing to
find LADOS.
DME is not required, so you can't assume you can use it to find LADOS -

yes,

even though it's clearly marked 5.2NM on the plate.
If you want to get into ELD without an ADF, you'll have to use one of the
other 3 approaches. Those aren't terrible options.

You're ignoring the feeder route from ELD to LADOS.

[Steven P. McNicoll]

or an approach certified GPS with LADOS as a waypoint, right?

The GPS does not need approach certification.

[Sydney Hoeltzli]

Post by Rich Raine
Wait! He can use a GPS in place of the ADF on that approach. Isn't that
correct?

I think so. But: Does the GPS need to be certified? If so (and I think so),
does it need to be approach certified or is enroute sufficient?

Certified, enroute/terminal suffices

Sydney

[John Clonts]

And the ILS plate is marked ADF required? Why is that?

... because you need to know where the LOM/IAF called LADOS is.
It's an IAF, so there's no previous fix from which you can start timing to
find LADOS.
DME is not required, so you can't assume you can use it to find LADOS -

yes,

even though it's clearly marked 5.2NM on the plate.

6.5 DME

[Brien K. Meehan]

Post by John Clonts

DME is not required, so you can't assume you can use it to find LADOS -

yes,

even though it's clearly marked 5.2NM on the plate.

6.5 DME

:-)

[Steven P. McNicoll]

Oh, right, sorry. I lost sight of the original premise, an ILS with ADF
"I think the alternate missed approach instructions still don't relieve

the

pilot of the requirement for carrying an ADF as explicitly stated on the
approach chart."

You're viewing the note "ADF REQUIRED" as having legal authority. I view it
as just a reminder that ADF is needed to fly the full approach, the missed
approach segment in this case. This isn't the first time this matter has
been discussed in this forum. As I recall from previous discussions, nobody
was able to present any definitive documentation in support of either view.
But logic tends to support the view that these notes are just reminders to
the pilot. Take a look at most LOC BC approaches and you'll find a similar
note that says "BACK COURSE". Is that a legal requirement that a back
course receiver must be aboard to fly the approach, or is it just a reminder
of reverse sensing?

[unknown]

Post by Steven P. McNicoll
You're viewing the note "ADF REQUIRED" as having legal authority. I view it
as just a reminder that ADF is needed to fly the full approach, the missed
approach segment in this case. This isn't the first time this matter has
been discussed in this forum. As I recall from previous discussions, nobody
was able to present any definitive documentation in support of either view.
But logic tends to support the view that these notes are just reminders to
the pilot. Take a look at most LOC BC approaches and you'll find a similar
note that says "BACK COURSE". Is that a legal requirement that a back
course receiver must be aboard to fly the approach, or is it just a reminder
of reverse sensing?

Of course its a requirement, that's why the word "required" is used. You
can use a GPS in substitute, but one or the other is required. "Radar
required" is also a frequently found note. Do you think that if the radar
is inop that day you can still shoot the approach because it was "just a
reminder"?

Paul Steichen
CFI, CFII, MEI, CRJ FO

[Steven P. McNicoll]

Post by unknown
Of course its a requirement, that's why the word "required" is used.

Can you present any definitive documentation in support of that view?

What requirement does the note "BACK COURSE" on a LOC BC approach present?

Post by unknown
"Radar required" is also a frequently found note. Do you think that if

the radar

Post by unknown
is inop that day you can still shoot the approach because it was "just a
reminder"?

I think if the radar is inop that day I won't be cleared for any approach
that requires radar.

[AJNOKC]

a) FAA 8260.19 is a source document for what I think you are looking for
(Including changes 1 & 2)
http://av-info.faa.gov/terps/Directives_files/8260.19C.pdf
b) Policy 01022, Documentation of Radar Requirements on Instrument Approach
Procedures
http://av-info.faa.gov/terps/Policies1/TIL01022.pdf


1) "ADF Required" - Par 814-h
-- on an ILS, most likely a NDB is used for the missed approach
2) "RADAR Required" - Par 814-g, and TILS 01022
-- What I have seen is that the IAF is defined off of the localizer beam
at some specific DME/crossing radial, or again, required for the missed

Cheers


On Sun, 27 Jul 2003 12:34:13 GMT, Steven P. McNicoll

Post by Steven P. McNicoll

Post by unknown
Of course its a requirement, that's why the word "required" is used.

Can you present any definitive documentation in support of that view?
What requirement does the note "BACK COURSE" on a LOC BC approach present?

Post by unknown
"Radar required" is also a frequently found note. Do you think that if

the radar

Post by unknown
is inop that day you can still shoot the approach because it was "just a
reminder"?

I think if the radar is inop that day I won't be cleared for any approach
that requires radar.

[Steven P. McNicoll]

Post by AJNOKC
a) FAA 8260.19 is a source document for what I think you are looking for
(Including changes 1 & 2)
http://av-info.faa.gov/terps/Directives_files/8260.19C.pdf
b) Policy 01022, Documentation of Radar Requirements on Instrument Approach
Procedures
http://av-info.faa.gov/terps/Policies1/TIL01022.pdf
1) "ADF Required" - Par 814-h
-- on an ILS, most likely a NDB is used for the missed approach
2) "RADAR Required" - Par 814-g, and TILS 01022
-- What I have seen is that the IAF is defined off of the localizer beam
at some specific DME/crossing radial, or again, required for the missed

Thank you. That explains how these notes appear on the plates, and suggests
why "ADF REQUIRED" appears on plates that can be flown completely without
ADF.

[j***@obilivan.net]

Post by Steven P. McNicoll

Oh, right, sorry. I lost sight of the original premise, an ILS with ADF
"I think the alternate missed approach instructions still don't relieve

the

pilot of the requirement for carrying an ADF as explicitly stated on the
approach chart."

You're viewing the note "ADF REQUIRED" as having legal authority. I view it
as just a reminder that ADF is needed to fly the full approach, the missed
approach segment in this case. This isn't the first time this matter has
been discussed in this forum. As I recall from previous discussions, nobody
was able to present any definitive documentation in support of either view.
But logic tends to support the view that these notes are just reminders to
the pilot. Take a look at most LOC BC approaches and you'll find a similar
note that says "BACK COURSE". Is that a legal requirement that a back
course receiver must be aboard to fly the approach, or is it just a reminder
of reverse sensing?

You're entitled to your view, of course. But, the "ADF REQUIRED" note is a
procedural data equipment note issued as part of an amendment to 14 CFR 97. If
in doubt, all the manager of AVN-100 and ask him whether the note is advisory in
nature. Also, AFS-400 many have a view somewhat different than your's.

[Steven P. McNicoll]

Post by j***@obilivan.net
You're entitled to your view, of course. But, the "ADF REQUIRED"
note is a procedural data equipment note issued as part of an
amendment to 14 CFR 97.

Can you cite a source for that?

Post by j***@obilivan.net
If in doubt, all the manager of AVN-100 and ask him whether the note is
advisory in nature. Also, AFS-400 many have a view somewhat
different than your's.

I'm not looking for another opinion, I'm looking for something definitive.

[Scott]

I was looking at this approach plate for my home field
http://www.myairplane.com/databases/approach/SouthCentral/ELD_ir22.pdf
And the ILS plate is marked ADF required? Why is that?

Looks like the NDB is part of the missed approach. You still don't need
an ADF, but only IF you have a /G approved GPS. (Though, you would still
need an ADF if this was an IFR alternate. For alternates - even if /G -
you need to have all the 'steam guage' equipment required for the
approach.

Scott

[j***@obilivan.net]

So this means I will need to install and ADF in the plane I'm building in
order to use the ILS approach?

Not necessarily. GPS can substitute for ADF and ATC can sometimes issue
alternate missed approach instructions.

I think the alternate missed approach instructions still don't relieve the pilot
of the requirement to have all the equipment mentioned in the title of the
approach chart. Of course, no enforcement action unless there's an incident.

The naming convention in TERPS was changed about 3 years ago to shorten titles, so
that they fit better in RNAV databases. Thus, what is required for an ILS approach,
for instance, is what is implied by the title and what is stated by any equipment
notes, such as "ADF required," etc.

Formerly, when DME was mandatory on an ILS approach the title would be ILS/DME, but
for any auch approach revised in the past couple of years, or in the future it will
state ILS in the title, then there will be an equipment note "DME required."

And, alternate missed approach procedures are not charted, thus generally known only
to the ATC facility, when they even exist. Even if a pilot knew such alternate
missed approach procedure existed, it is not a reality unless the controlling ATC
facility assigns it once you're in their airspace and under their control.

[j***@obilivan.net]

Rich,

Post by Rich Raine
Wait! He can use a GPS in place of the ADF on that approach. Isn't that
correct?

I think so. But: Does the GPS need to be certified? If so (and I think so),
does it need to be approach certified or is enroute sufficient?

IFR certified, but approach certification is not required.