"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---