Questions tagged [ils]

An instrument landing system (ILS) is a ground-based instrument approach system that provides precision guidance to an aircraft approaching and landing on a runway.

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27
votes
2answers
55k views

How does ILS (Instrument landing system) work?

How does ILS (Instrument landing system) work? I know it provides guidance to the runway by two signals, one modulated at 90 Hz, the other at 150 Hz, but how the airplane lock on those signals? ...
56
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6answers
16k views

Instrument landing: why do all electronic devices need to be shut off?

A few days ago, I took a flight home. Towards the end of the journey, the captain asked us to shut down any electronic device that we had on board, including iPods, CD players, phones and so on, ...
13
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1answer
1k views

Are zero visibility landings a possibility for the future of commercial aviation?

Airports usually close or slow down activities in fog conditions, e.g. this seems to be a significant problem in winter at Delhi airport. Large commercial aircraft would be able to land with no ...
7
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2answers
7k views

Is it true an ILS CAT IIIc can automatically taxi-in an aircraft?

I've always wondered how would the theoretical (since no airport/plane has it) ILS CAT IIIc guide the plane off the runway? I mean from the perspective of radio signals. What component in the ILS ...
20
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4answers
96k views

What is different between a Cat IIIA, Cat IIIB, and Cat IIIC ILS approach?

In terms of aircraft equipment, approach minimums, procedural differences, and anything else relevant, how do the 3 types of a Cat III ILS differ from one another?
13
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2answers
9k views

How is varying modulation depth achieved by localizer ground transmitters?

An approaching aircraft's navigation receiver uses the difference in depth of modulation between the 90Hz and 150Hz signals which are amplitude modulated onto an RF carrier (on a channel between ...
3
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1answer
5k views

Is there a list of airports with Category 3 ILS systems?

Is there a list of airports with category 3 Instrument Landing Systems?
8
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2answers
703 views

How do preceding aircraft affect the ILS signals?

(airliners.net) Planes on approach in sequence to London Heathrow. When LVP is in effect, the ILS area is protected. I'm wondering, when there is a queue to a runway, how does the long queue affect ...
29
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1answer
10k views

What is the behavior of false glideslope signals?

I know that an ILS transmits not only the correct glideslope but also signals that can be interpreted as a false glide path. But I'm not familiar with the details of these erroneous indications. What ...
9
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3answers
5k views

What makes a visual approach quicker than an ILS approach?

In the question What's the preferred approach for a passenger jet? it is mentioned that pilots prefer Visual Approaches over ILS Approaches, as they are a lot quicker. Why would a visual approach ...
8
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1answer
2k views

Can a pilot use ILS when cleared for a visual approach?

When cleared for a visual approach, do airline pilots still use the localiser/glideslope or GPS or even the autopilot, or is it strictly a "visual" approach?
7
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2answers
1k views

Could a terrorist hack the ILS?

I'm reading all these reasons why consumer electronics can't be on during takeoffs and landings and one specific reference that is made over and over again is the sensitivity of the ILS equipment. I ...
13
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1answer
2k views

Do non-towered airports commonly have ILS?

Is it common, uncommon or rare for a non-towered airport to have ILS (Instrument Landing System) runways? Can a non-towered airport have ILS?
12
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1answer
12k views

What is the difference between "Land 2" and "Land 3" annunciations for Boeing autopilot systems?

Another question's answers refer to certain Boeing jets having the capability to annunciate "Land 2" and "Land 3" when flying a coupled ILS approach. What does each of these modes require, and allow, ...
9
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1answer
2k views

What's the point of having ILS on runway signs?

Runway signs show the ILS category next to the runway designation. But if you flew and didn't drive to the airport, you already know (hopefully). Either way, you are taking off, so you don't really ...
7
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1answer
6k views

Is there any airport planning to install ILS CAT IIIc?

I know that right now no airport has an ILS CAT IIIc, but is there any airport in the world planning to have one in a near future? Otherwise why bother to have rules and specifications for something ...
3
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4answers
10k views

What are the lowest authorized minimums for each ILS category?

I have been recently told that ILS minimums were changed some time ago. Could anyone tell me what the lowest authorized ILS minimums are for CAT I, CAT II, CAT IIIa, CAT IIIb and CAT IIIc? I'm ...
16
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2answers
2k views

What is a monitored approach?

I've heard this term used to describe approaches into low weather (e.g. category 2 ILS), what is it? How is this different than an ILS approach?
12
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2answers
1k views

Why are sidestep ILS minima not used in EASA-land? (specific example: EGKK)

If you are not aware, London Gatwick (aka EGKK) has a setup with a primary air carrier runway and a backup runway immediately next to it, such that only one runway can be used at a time. The main ...
7
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2answers
11k views

What is the difference between the ILS Critical Area and the ILS Sensitive Area?

What's the difference between the ILS Critical Area vs ILS Sensitive Area? I'm getting multiple conflicting opinions online. e.g. I can't decipher from this set of definitions how exactly they ...
21
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3answers
5k views

How precise is an ILS (Instrument landing system)?

I read that an ILS is a precision approach system. It provides a final approach with precision in both horizontal and vertical guidance to the runways. But I don't know how precise it is because there ...
14
votes
1answer
29k views

What are the differences between Cat I, Cat II, and Cat III as concerns aircraft requirements?

I understand that Cat I, II, and III ILS approaches have progressively smaller weather minimums. However, I am asking about the aircraft themselves. What are the differences between Cat levels as ...
8
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4answers
10k views

Can the ILS glideslope be intercepted from above?

Is it recommended to intercept the ILS glideslope from above? Are there any special considerations like unstable approaches or GPWS warnings?
6
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1answer
552 views

Can two opposite localizers to a single runway be on simultaneously?

In case of a single runway with two separate ILS systems (one in each end, facing localizers) operating on two different frequencies, can both localizers be on and transmitting at the same time, or ...
3
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1answer
2k views

Why does the glideslope use UHF when the localiser uses VHF band?

Why does the glideslope use UHF, while the localiser uses the VHF band? I mean, the glideslope could have used the VHF band too, or vice versa, so why is it so?
3
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1answer
265 views

What is the behaviour of ILS when there is an unmodulated interfering carrier signal?

Let us assume we have a localizer (identifier I-STK) transmitting at 110.10MHz and a matching glideslope at 334.40MHz. If a device aboard an aircraft tracking the I-STK ILS were to emit an ...
15
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3answers
3k views

Is it legal to land in bad visibility conditions without ILS?

Korean Air Flight 801 crashed during bad visibility conditions in Guam because the ILS was out of commission and the pilot thought it wasn't. My question though is why he even tried to land there in ...
14
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3answers
16k views

When do pilots disconnect the autopilot on an ILS approach?

In clear weather, when do pilots disconnect the autopilot, if the plane is flying an ILS approach and the autopilot is in "approach" mode (tracking both localizer and glideslope)? Would the answer ...
11
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1answer
403 views

How does an eILS improve throughput (for the A380)?

While researching where Heathrow's MLS approachs had gone, the only thing I could find is a topic on Heathrow's new eILS (enhanced ILS). As of the topic's date (Aug 2015) it seems eILS is only ...
10
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1answer
8k views

Precision Approach systems: Why is ILS used more frequently than PAR and MLS?

I have studied that the main three systems for performing Precision Approaches (PA) are the ILS (Instrumental Landing System), PAR (Precision Approach Radar) and MLS (Microwave Landing System). ...
7
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2answers
994 views

Why does this Garmin GMA340 have an Airway/Inner marker indicator?

On this Garmin GMA 340: the outer marker is blue and is designated O the middle mark is amber and is designated M the inner marker is white and is designated A and placed on the far left. I looked ...
6
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1answer
5k views

Can I make an ILS-Approach when I am VFR?

When doing a VFR-Flight, the runway to land on is usually approached visually. However, I would like to do some ILS-Training but in VFR. Is that possible? If yes: What's the procedure? Do I have to ...
5
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1answer
412 views

Can a deployable ILS operate in CAT II or CAT III?

Can a deployable ILS operate in CAT II or CAT III? As far as I know a deployable ILS can operate only in CAT I.
4
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1answer
2k views

How do you choose CAT II vs. CATIII ILS?

When should we use CAT II or III during landing in bad weather? What we have in our country the standard shows 800m and RVR of 550 m for the ILS, which category procedure should be used if the ...
4
votes
1answer
17k views

What is a localiser back-course approach and how does it work?

What does back-course approach mean ? How much signal strength should the back lobe of ILS should have in order to trace it and commence landing. How common is this type of landing for a pilot. What ...
3
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5answers
7k views

Is the ILS only used for landing when weather conditions are poor? [duplicate]

Either I'm missing something, or this article clearly suggests, that pilots are using ILS for landing only in bad weather conditions. Which could lead to an assumption, that in perfectly clear weather ...
3
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2answers
2k views

How far back from the final approach fix can you intercept the glideslope?

I was looking for the point that you engage your auto pilot approach glide slope before the final approach fix in this question. How far back can you go?
2
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2answers
1k views

Can I do a CAT III ILS approach if minimums are above CAT I?

I was going to an airport with weather at minimum for CAT I approach. Not wanting to know whether or not I could make it I thought about asking ATC if I could do a CAT III approach even though the ...
2
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1answer
3k views

What is an obstacle identification surface and why would a pilot intentionally penetrate it during an ILS approach?

What is an obstacle identification surface? Why would a pilot intentionally penetrate it during an ILS approach?
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0answers
103 views

Is it necessary to switch from VFR to IFR when using ILS approach?

I have flown at an airport and asked for vectors for an ILS approach in VMC for practice. But the controller refused to give me vectors and told me that I could only have a visual approach. I got the ...