IFR hold short line at uncontrolled airports?

Ron Natalie wrote:

"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.


My home airport, N38, doesn't. :-)


Matt

The longer runways are more likely to have critical areas.

Why?

Jose

--
(for Email, make the obvious changes in my address)

Teacherjh wrote:
The longer runways are more likely to have critical areas.


Why?

The localizer will be closer to the (opposite) runway threshold.


All the best,


David

In article
ogers.com,
David Megginson wrote:

Teacherjh wrote:
The longer runways are more likely to have critical areas.


Why?

The localizer will be closer to the (opposite) runway threshold.


All the best,


David

Why should runway length affect how far the localizer antenna is from
the runway end?

Localizers are designed to have a fixed width (something like 700 ft
lateral displacement for full-scale deflection on the CDI) at the
arrival threshold, so longer runways will have narrower angular beam
widths. But (to the best of my knowledge) this is done by adjusting the
spacing of the transmitting elements on the localizer array, not by
adjusting the distance of the array from the runway end.

Localizers are designed to have a fixed width (something like 700 ft
lateral displacement for full-scale deflection on the CDI) at the
arrival threshold, so longer runways will have narrower angular beam
widths.


Doesn't make sense to me. Angular beam width should be constant - for the far
field. Then the antenna is placed at the distance from the arrival end (also
constant) that gives the proper width.

No?

Jose



--
(for Email, make the obvious changes in my address)

"Teacherjh" wrote in message
...
The longer runways are more likely to have critical areas.

Why?

Because the localizer spreads out at a constant rate. The longer the runway
the wider it will be at the end of the runway.

"Newps" wrote in message
...

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.

They can't "focus" or "tighten" the signal for longer runways???

"Newps" wrote in message
...

Because the localizer spreads out at a constant rate. The longer the
runway
the wider it will be at the end of the runway.


But the localizer critical area doesn't extend to the end of the runway.
For a category I ILS it typically extends only 2000 feet from the antenna
array.

"Newps" wrote in message
...

The longer runways are more likely to have critical areas. Runways whose
taxiways get too close to the runway is also a factor. We have that
problem
here at BIL. The last 3000 feet of taxiway angles in toward the runway
creating the need for an ILS hold area because you get in the way of the
localizer.


The ILS hold at BIL is near the east end of runway 10L/28R. It's there to
protect the localizer for the ILS RWY 10L, not the localizer for the ILS RWY
28R.

"David Megginson" wrote in message
le.rogers.com...

The localizer will be closer to the (opposite) runway threshold.


So what?