Today I dropped an Angel Flight patient off at Massena, NY (KMSS), an
uncontrolled airport in the very north portion of NY state. The weather
was 50 feet above minimums and the ILS was the only way in.

Once the patient was safely in the warm terminal, I preflighting and
started up, only to learned that there was an Air Midwest B1900 ten
minutes out. Flight Service could not release me until the B1900 was
down and canceled IFR.

To ensure that I was ready to go, I taxied to the departure end and
performed the pre-takeoff checklist. Then it hit me. There was no ILS
hold short line marked, yet weather was right at minimums and I was sure
I was beyond the ILS transmitter tower.

So as not to potentially interfere with the ILS signal, I turned around
and taxied back to what I believe was the transmitter tower (it was
dark) and waited for the aircraft to land.

Did I overreact, or should there be ILS hold short lines at uncontrolled
airports with ILS approaches?

--
Peter







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If there's a need for you to hold at a certain point they will put the lines
and the signs on the taxiway. If there's no need then there won't be any.
In your case you didn't need to move. You were fine where you were.


"Peter R." > wrote in message
...
> Today I dropped an Angel Flight patient off at Massena, NY (KMSS), an
> uncontrolled airport in the very north portion of NY state. The weather
> was 50 feet above minimums and the ILS was the only way in.
>
> Once the patient was safely in the warm terminal, I preflighting and
> started up, only to learned that there was an Air Midwest B1900 ten
> minutes out. Flight Service could not release me until the B1900 was
> down and canceled IFR.
>
> To ensure that I was ready to go, I taxied to the departure end and
> performed the pre-takeoff checklist. Then it hit me. There was no ILS
> hold short line marked, yet weather was right at minimums and I was sure
> I was beyond the ILS transmitter tower.
>
> So as not to potentially interfere with the ILS signal, I turned around
> and taxied back to what I believe was the transmitter tower (it was
> dark) and waited for the aircraft to land.
>
> Did I overreact, or should there be ILS hold short lines at uncontrolled
> airports with ILS approaches?
>
> --
> Peter
>
>
>
>
>
>
>
> ----== Posted via Newsfeed.Com - Unlimited-Uncensored-Secure Usenet
News==----
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Newsgroups
> ---= 19 East/West-Coast Specialized Servers - Total Privacy via Encryption
=---

Peter R. > wrote:
: Did I overreact, or should there be ILS hold short lines at uncontrolled
: airports with ILS approaches?

What you did was most likely not necessary, as I'm sure if the hold short line
was required it would have been there. Just as a datapoint, however, an untowered
airport near here (PSK) has an ILS with an ILS hold short. It's not just for towered
fields.

-Cory

--
************************************************** ***********************
* The prime directive of Linux: *
* - learn what you don't know, *
* - teach what you do. *
* (Just my 20 USm$) *
************************************************** ***********************

In article >, Peter R.
> writes:

>So as not to potentially interfere with the ILS signal, I turned around
>and taxied back to what I believe was the transmitter tower (it was
>dark) and waited for the aircraft to land.
>
>Did I overreact, or should there be ILS hold short lines at uncontrolled
>airports with ILS approaches?

I don't think you over reacted tho it probably (not for damn sure) was not
necessary. That sort of consideration is mostly missing in todays world and I
salute you for doing the extra. You'll never know but with that ceiling you
may just be partially responsible for his safe landing!!

Chuck

Peter R. wrote:

> Today I dropped an Angel Flight patient off at Massena, NY (KMSS), an
> uncontrolled airport in the very north portion of NY state. The weather
> was 50 feet above minimums and the ILS was the only way in.
>
> Once the patient was safely in the warm terminal, I preflighting and
> started up, only to learned that there was an Air Midwest B1900 ten
> minutes out. Flight Service could not release me until the B1900 was
> down and canceled IFR.
>
> To ensure that I was ready to go, I taxied to the departure end and
> performed the pre-takeoff checklist. Then it hit me. There was no ILS
> hold short line marked, yet weather was right at minimums and I was sure
> I was beyond the ILS transmitter tower.
>
> So as not to potentially interfere with the ILS signal, I turned around
> and taxied back to what I believe was the transmitter tower (it was
> dark) and waited for the aircraft to land.
>
> Did I overreact, or should there be ILS hold short lines at uncontrolled
> airports with ILS approaches?
>

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.


Matt

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.

"Peter R." > wrote in message
...
>
> 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?
>

Towered fields tend to have more operators to accommodate so they have more
ramp space and taxiways, thus a greater opportunity to enter critical areas.


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

And if it can't be passed by an aircraft on a taxiway it isn't a problem.
If access to the runway is from just one side and the glideslope transmitter
is on the far side of the runway it can't be passed by an aircraft on a
taxiway. That's the situation you find at most uncontrolled fields.

"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---

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

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 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.
>
Of course, the localizer is off the end of the runway. The glideslope is in the
vicinity of the touchdown zone. Since they don't last too long if they stick then
in the touchdown zone, you've got at least two possibilities for siting (one on each
side of the runway).

"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.

In article .net>, "Steven
P. McNicoll" > writes:

> It seems to me that any ILS antenna that can be passed by an aircraft on
>> a taxiway would be prone to interference.
>>
>
>And if it can't be passed by an aircraft on a taxiway it isn't a problem.
>If access to the runway is from just one side and the glideslope transmitter
>is on the far side of the runway it can't be passed by an aircraft on a
>taxiway. That's the situation you find at most uncontrolled fields.
>

A story why you need a safety pilot. I was on a practice ILS at KLPR ( a non
towered airport) and the glide slope needle was "right on". Safety pilot said,
"Chuck, take off your hood, you are getting pretty low." We sure were, but no
glideslope flag. Advance power and as we over fly the field, we see that they
are mowing around the antenna. Now on any ILS, I like to be one mark high on
the glideslope. ILS runways are long for my Archer and it better insures that
all is OK.

Chuck

"Ron Natalie" > wrote in message
. ..
>
> All runways have an ILS critical area.
>

Actually, it's just those with an ILS. And runways with a full ILS have two
critical areas, a Localizer Critical Area and a Glideslope Critical Area.


>
> The issue is whether there is a taxiway that passes through it or not.
>

To help illustrate this I've posted two figures from FAA Order 6750.16,
"Siting Criteria for Instrument Landing Systems", in
alt.binaries.pictures.aviation. The subject is ILS Critical Areas.

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.



"Matt Whiting" > wrote in message
...
> 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
>

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
gers.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?

Yes, they can adjust the localizer width. An example is listed below for
Billings MT ILS. (BIL) If you scroll through the data, you'll notice the
LOC width is listed as 3.34 degrees under AFIS DATA.
JPH

Date:06/08/04 22:37pm * * * ILS INQUIRY - ACTIVE * * * DATUMS Horz:
NAD83 Vert: NAVD88 CTRY: US
AIRPORT: BILLINGS LOGAN INTL ARPT-ID: KBIL RWY: 10L LCTN: BILLINGS ST:
MT REG: NM FIFO: SAC OWN: F

--------------------------------------------------------------------------------

* * * AFIS DATA * * *
IDENT BIL GLA N45-48-44.87 GS-OFF L350 GS-LC-DIS 10875
RW-BRG 111.71 GLO W108-33-00.63 GS-OM-DIS 39546 LC-OFF
FREQ 110.300 GS-ANG 3.00 GS-TH-DIS 1135 LC-FCB 111.71
MVAR 1990/E14 GS-WID 0.70 TH-HGT 3584 LC-BCB 291.73
CAT I GS-HGT 3571.5 RE-HGT 3488 LC-WID 3.34
R-LDG-LGTH 10518

--------------------------------------------------------------------------------
* * * LOCALIZER * * * (DFL CODE - ILS/L)
ANT LAT N45-48-01.93 XMTR SINGLE LOC-RE 1492/ 0.246 LCW-TAIL YES
ANT LON W108-30-39.88 EQUIP-TYPE ST LOC-TH 12010/ 1.977 LCW-FT-TH 700
ELEV 3491.9 STBY-POWER G LOC-IM DATE-COMM 12/18/87
ANT-TYPE LOG-PER ESV N LOC-MM 15179/ 2.498 DATE-RECON
DUAL-FREQ NO RESTRICTED N LOC-OM 50421/ 8.298 SURVEY-ACCY 8
US-DIST: FC 7989/ 18.0 BC LOC-FAF VOICE NONE
CLRNC-CVG:FC 90/31 150/30 BC MON-AL-WID W 3.90 N 2.78 REC TYPE
CKPT-DESC: FC LOM(8.28NM) TO LOC BC
LOC-WIDTH-MX-ALERT: 3.68/ 3.00 LOC-AL-MX-ALERT: 9uA ROLLOUT: S
LOC-WIDTH-INITIAL: 3.81/ 2.87



Tom Sixkiller wrote:
> "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???
>
>