IFR hold short line at uncontrolled airports?

Matt Whiting ) wrote:

The ILS antenna doesn't know if the field has a control tower or not.
If an ILS hold is needed, then the taxiway would be marked.

And conversely, if ILS hold short lines are needed at most towered
airports, why are they not needed everywhere? What makes certain ILS
arrangements prone to interference and others not?

It seems to me that any ILS antenna that can be passed by an aircraft on
a taxiway would be prone to interference.

--
Peter












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"Peter R." wrote in message =
...
Matt Whiting ) wrote:=20
=20
The ILS antenna doesn't know if the field has a control tower or =
not.=20
If an ILS hold is needed, then the taxiway would be marked.
=20
And conversely, if ILS hold short lines are needed at most towered=20
airports, why are they not needed everywhere? What makes certain ILS=20
arrangements prone to interference and others not? =20
=20
It seems to me that any ILS antenna that can be passed by an aircraft =
on=20
a taxiway would be prone to interference.
--=20
Peter
=20

Since the glideslope antenna pattern relies upon ground reflections,
it is easy to see why ILS hold-short lines can be needed where taxiways
are on the same side of the runway as the glideslope antennas.
Large blobs of metal, moving or not, can disturb those ground =
reflections.

Taxiways opposite the glideslope-antenna side are more likely to be
free of the ILS hold-short restrictions. It just depends upon the =
geometry.
---JRC---

John R. Copeland ) wrote:

Taxiways opposite the glideslope-antenna side are more likely to be
free of the ILS hold-short restrictions. It just depends upon the geometry.

OK, that may be the information I lacked. Thanks.

--
Peter












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Peter R. wrote:

Matt Whiting ) wrote:


The ILS antenna doesn't know if the field has a control tower or not.
If an ILS hold is needed, then the taxiway would be marked.


And conversely, if ILS hold short lines are needed at most towered
airports, why are they not needed everywhere? What makes certain ILS
arrangements prone to interference and others not?

It seems to me that any ILS antenna that can be passed by an aircraft on
a taxiway would be prone to interference.


I suspect it has to do with the location of the antenna. I don't they
they are all located in exactly the same spot WRT to the runway.


Matt

"Matt Whiting" wrote in message
...



I suspect it has to do with the location of the antenna. I don't they
they are all located in exactly the same spot WRT to the runway.

The glideslopes are as they are all positioned to bring you to the same spot
on every runway. The localizer is sited so it is a certain width at the
approach end of the runway, therefore they will move the localizer antenna
closer to or farther away from the departure end of the runway to achieve
that.

"Newps" wrote in message =
...
=20
"Matt Whiting" wrote in message
...

I suspect it has to do with the location of the antenna. I don't =
they
they are all located in exactly the same spot WRT to the runway.
=20
The glideslopes are as they are all positioned to bring you to the =
same spot
on every runway. The localizer is sited so it is a certain width at =
the
approach end of the runway, therefore they will move the localizer =
antenna
closer to or farther away from the departure end of the runway to =
achieve
that.
=20

By far the most impressive localizer antenna I've ever seen
is on the top of Aspen Mountain, aimed out across the Pitkin County =
Airport
and the valley beyond to the northwest.
It's an array of, I think, sixteen rugged Yagis over an expanded-metal =
screen.
However, I doubt that localizer course width at any threshold was a =
factor
in the design of this particular installation. It's for missed =
approaches only.
---JRC---

On Wed, 26 May 2004 17:13:43 -0600, "Newps" wrote:

The glideslopes are as they are all positioned to bring you to the same spot
on every runway.

Well, not exactly. The glide slope transmitter is located between 750
feet and 1,250 feet from the approach end of the runway (down the runway)
and offset 250 to 650 feet from the runway centerline.

And it can be on either side of the runway.


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

"Ron Rosenfeld" wrote in message
...

And it can be on either side of the runway.


And if there's a taxiway on just one side of the runway, the GS transmitter
tends to be on the other side of the runway.

Newps wrote:

"Matt Whiting" wrote in message
...



I suspect it has to do with the location of the antenna. I don't they
they are all located in exactly the same spot WRT to the runway.


The glideslopes are as they are all positioned to bring you to the same spot
on every runway. The localizer is sited so it is a certain width at the
approach end of the runway, therefore they will move the localizer antenna
closer to or farther away from the departure end of the runway to achieve
that.



Then why do some runways have ILS critical areas and others do not?

Matt

"Matt Whiting" wrote in message ...

Then why do some runways have ILS critical areas and others do not?

All runways have an ILS critical area. The issue is whether there is a taxiway that passes
through it or not.