Why is ADF required on ILS approach?

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

Rich Raine
www.eraine.com


"Brien K. Meehan" wrote in message
...
"Gig Giacona" wrote in message
...
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.

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)

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.


"Thomas Borchert" wrote in message
...
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)

"Gig Giacona" wrote in message
...
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

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"
wrote:

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.


"Thomas Borchert" wrote in message
...
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)

"Leland Vandervort" wrote
in message ...

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

"David Brooks" wrote in message
...

"Leland Vandervort"
wrote
in message ...

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.

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.

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

Leland Vandervort writes:

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

--
David Megginson, , http://www.megginson.com/

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

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

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/...l/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.