IFR hold short line at uncontrolled airports?

"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.

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. 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

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

"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 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.

"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).

"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???

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???