julesmusician
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ILS Protected Comment By Air Traffic

Mon Nov 28, 2005 8:58 am

ILS protected I have taken to mean as not allowing any aircraft to get in the way of the radio signal by blocking it can someone confirm if this is true? Also how does this work - if you have a nice trail of aircraft in on finals then the ILS signal cannot be protected all the way out so can you lose signal coming in and what effect might this have on the approach?

J
African Civil Aviation Commission president "You don't want to fly out as a passenger and come back as cargo."
 
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vzlet
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RE: ILS Protected Comment By Air Traffic

Mon Nov 28, 2005 10:34 am

I'm not sure if this is the same thing you're talking about, but in the US, "ILS Critical Area" is used to designate a zone on the ground that taxiing aircraft should avoid when the ILS is in use, lest they interfere with the signal.
For an example, see the threshold of runway 10R in this diagram of Monterey Peninsula (MRY).
"That's so stupid! If they're so secret, why are they out where everyone can see them?" - my kid
 
TimT
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RE: ILS Protected Comment By Air Traffic

Mon Nov 28, 2005 11:56 am

ILS Protected Area and ILS Critical Area would be the same. Detroit Metro has a couple of taxiways that have not only a "Runway Threshold" mark, but also an "ILS Hold". If the runway is in use then the ILS mark is used keeping the taxiing a/c back further from the runway. Even if it's not in use, I ALWAYS double check permission to cross the ILS line and also verify runway clearances. If the weather is actual ILS conditions and you cross over the hold line you may block either the glideslope or the localizer (or both) and someone does a go around. And someone else gets that dreaded message "Call the Tower" or gets met by an inspector.
 
julesmusician
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RE: ILS Protected Comment By Air Traffic

Mon Nov 28, 2005 7:46 pm

Thanks for that I was just wondering whether aircraft all lined up to land could cause problems for the aircraft behind on finals, but it appears not, sounds like it is just something for aircraft on the ground to beware of. Thanks.
African Civil Aviation Commission president "You don't want to fly out as a passenger and come back as cargo."
 
Key
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RE: ILS Protected Comment By Air Traffic

Mon Nov 28, 2005 8:20 pm

Yep, can confirm that. To disturb the ILS signal you have to be so close to the transmitter that you'd be on the ground. If you were flying that close you could disturb it as well, but only for a very short moment.
Keep in mind the glide slope antenna is to the side of the runway, so a landing aircraft will not obstruct it for the one behind in the final stages of flight. Likewise, the localizer is past the end of the runway, 'looking over' the one ahead that is touching down.
ILS Critical and Sensitive Areas, making up the Protection Area together, exist only on the ground. The worse the weather, the more protection is needed.

Erik
 
jush
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RE: ILS Protected Comment By Air Traffic

Mon Nov 28, 2005 9:17 pm

I wonder what they thought about ILS protection after the Atlas Air 747-200 rushed into the ILS antenna in DUS Big grin

Regds
jush
There is one problem with airbus. Though their products are engineering marvels they lack passion, completely.
 
VuelingAirbus
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RE: ILS Protected Comment By Air Traffic

Mon Nov 28, 2005 11:55 pm

Quoting Julesmusician (Reply 3):
Thanks for that I was just wondering whether aircraft all lined up to land could cause problems for the aircraft behind on finals, but it appears not, sounds like it is just something for aircraft on the ground to beware of. Thanks.

You are wrong. It is a huge problem. Spacing of landing traffic is double or more in actual low visibility operations (I think I mentioned that to you in one of your previous threats already). That's the reason why the runway capacity is less than half in foggy conditions.

rgds
 
A350
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RE: ILS Protected Comment By Air Traffic

Tue Nov 29, 2005 5:20 am

IS it an urban legend or is it true that the cars and trucks at the motorway at FRA are also disturbing the ILS signal?

A350
 
bond007
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RE: ILS Protected Comment By Air Traffic

Tue Nov 29, 2005 6:04 am

Quoting VuelingAirbus (Reply 6):
Spacing of landing traffic is double or more in actual low visibility operations

Yep!

...Lawson was referring to the approximate doubling of the normal Cat I spacing between aircraft when they fly Cat III ILS approaches or, as the Europeans describe them, low-visibility procedures (LVPs). The additional spacing is required because aircraft on final during an ILS approach create signal multipath disturbances to the localizer beam, which, depending on the shape and size of the aircraft can last many seconds, and even minutes, before becoming stable again. Call it electronic wake turbulence.

This effect was dramatically demonstrated at London Gatwick Airport some years ago when a Swissair MD-80 requested a practice ILS autoland on a VFR day while following a Boeing 737 on final. All went well until the MD-80 was crossing the threshold, just as the 737 exited the runway and presented its vertical fin broadside on to the ILS localizer transmitter at the stop end of the runway. At 50 ft, the MD-80 went into a steeply banked right turn as its autopilot attempted to follow the localizer, which had been momentarily reflected off the centerline by the 737, and only quick action by the crew avoided a disaster."

Quoting A350 (Reply 7):
IS it an urban legend or is it true that the cars and trucks at the motorway at FRA are also disturbing the ILS signal?

.."Frankfurt’s Runway 25R ILS currently has a notam describing random but severe interference that affects its ILS guidance, and advises extreme operator caution. The interference is thought to come from a nearby satellite cable TV transmitter, but the airport authority is reportedly finding it difficult to prove that this is the source of the problem.

Several years ago, it was forecast that many ILS installations in Europe could be down-categorized due to expected interference from commercial FM broadcast stations operating just outside the ILS frequency band, and which were about to be allowed to increase their transmitter power. As a result, the Europeans mandated the carriage of interference-rejecting ILS receivers in aircraft operating in their airspace. Before the mandate went into effect, pilots frequently reported hearing rock music and radio commercials while listening for the ILS idents at certain European airports."


Jimbo
I'd rather be on the ground wishing I was in the air, than in the air wishing I was on the ground!
 
Key
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RE: ILS Protected Comment By Air Traffic

Tue Nov 29, 2005 8:56 am

Quoting VuelingAirbus (Reply 6):


Quoting Julesmusician:

Thanks for that I was just wondering whether aircraft all lined up to land could cause problems for the aircraft behind on finals, but it appears not, sounds like it is just something for aircraft on the ground to beware of.

You are wrong. It is a huge problem. Spacing of landing traffic is double or more in actual low visibility operations

It seems to me you are talking about different things here. Spacing is increased for CAT-II/III operations in order to have the protection area on the ground cleared in time before the next landing clearance is issued. This both takes longer in really bad visibility (maneuvering is more difficult) and concerns a larger area as conditions deteriorate.
I have never heard of the aircraft flying on (final) approach posing a threat to the ILS signal for those behind them. This is mainly related to the distance to the antennae, as mentioned before.

Erik
 
Tornado82
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RE: ILS Protected Comment By Air Traffic

Tue Nov 29, 2005 8:57 am

Quoting Bond007 (Reply 8):
Before the mandate went into effect, pilots frequently reported hearing rock music

Just keeping them entertained in case they get caught in a hold  Wink
 
Key
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RE: ILS Protected Comment By Air Traffic

Tue Nov 29, 2005 4:51 pm

Quoting Bond007 (Reply 8):
This effect was dramatically demonstrated

Forgot to mention, there is a phrase regarding practice CAT-III approaches: "All the elements are available". This means the ILS at that moment supports CAT-III operations and the protection area will be clear in time. In the described case, clearly not all of the elements were available.

Erik
 
jush
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RE: ILS Protected Comment By Air Traffic

Tue Nov 29, 2005 6:52 pm

Quoting Bond007 (Reply 8):
pilots frequently reported hearing rock music and radio commercials while listening for the ILS idents at certain European airports."

Hehe that must be strange while you'll try to get the ILS in you hear.
Hi this is THE WHO on NDR2 you're listening to your favourite ILS stream  Wink

Regards
jush
There is one problem with airbus. Though their products are engineering marvels they lack passion, completely.

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