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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56
votes
6answers
15k 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, ...
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 ...
27
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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? ...
24
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1answer
4k views

Was it possible to land a Boeing 707 with 300 feet cloud ceiling in the 70s?

In the movie Airplane! (1980), the main characters had to land a Boeing 707 in Chicago airport in low visibility. The dialog says the pilot "should be able to see the runway at 300 feet". Given the ...
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 ...
20
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4answers
95k 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?
17
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1answer
2k views

Does a portable ILS ground station exist?

Does anyone know of a good example of a portable ILS ground station? I mean, it can be used for temporary airfields.
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?
15
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3answers
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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
15k 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 ...
14
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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 ...
13
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2answers
8k 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 ...
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?
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 ...
12
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2answers
2k views

What is the correct name for this ILS Indicator?

What is the correct terminology for the name of the aircraft instrument that looks like this?
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, ...
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 ...
11
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3answers
2k views

Is it possible for more than one airplane intercept the ILS at the same time?

I was watching a timelapse video yesterday of the approaches on a busy airport (I don't remember which one), and I saw that about 3 or 4 planes were lined up and descending at the same time (they were ...
11
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1answer
14k views

What is the purpose of having different ILS categories?

What is the difference between CAT I, II and III ILS approaches? I understand that the different categories are used in different weather, but what are the differences, exactly? Do flight crews have ...
11
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1answer
401 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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3answers
2k views

Why would the USAF have no support for autolanding?

One thing I noticed when reading through the KC-10 flight manual (see page 184 for the specific reference) is that the KC-10 lacks support for Category III operations, unlike its civil DC-10 brethren. ...
10
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2answers
809 views

Why haven't helicopter CAT III procedures ever been developed?

Why is there no helicopter equivalent to air transport CAT III ILS? This PPrUNe thread discusses that some helicopter manufacturers have tested coupled approaches down to very low visibility minima (...
10
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2answers
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What is the maximum interception angle for ILS when on radar vectoring?

Some time ago when I was designing the approach radar module for the ATC simulator for HCAA, the spec was very clear that the limit had to be placed at 45 degrees. So I took it for granted and I didn'...
10
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1answer
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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). ...
10
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1answer
157 views

Why are different distances listed for the ILS and the LOC on this approach chart?

Maybe someone has an idea why are there two separate distance values (marked in blue) for ILS and LOC approaches?
10
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1answer
270 views

Why would an ILS have a glide path angle less than the preferred 3°?

According to EASA the preferred Glide Path Angle is 3°: EASA Easy Access Rules - Page 22 - 4.1.2.1. There are some airports (e.g. Larnaca 2.75°) which are using a lower Glide Path Angle than 3°. Using ...
9
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3answers
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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 ...
9
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2answers
3k views

How does a pilot select the correct ILS when the airport has parallel runways?

How do you not mess up ILS on parallel runways? There are many airports with ILS and parallel runways, how do you select which ILS for the runway you want? For example there are RWY 22L AND 22R and ...
9
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1answer
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What is "(CFMCC)" on an ILS approach chart?

I'm studying the ILS or LOC RWY 3 approach chart for KMKC. I'm trying to figure out what "(CMFCC)" at the runway means. Is it a computer navigation aid?
9
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3answers
805 views

What prevents the use of a multi-segment ILS for non-straight approaches?

An ILS, consisting of a localiser beam to provide lateral guidance (which can also be used on its own for a non-precision approach) and a glideslope beam to provide vertical guidance, is (currently) ...
9
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3answers
3k views

Why would a PAPI and ILS glide slope for the same runway not coincide?

Some pilots are reporting the glide slope on our PAPI is not coinciding with the glide slope on our ILS even though FAA did a flight check of our PAPI's. Are there any reasons why a PAPI and ILS would ...
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 ...
9
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2answers
442 views

What should I do if I intercept the glideslope before reaching the final approach fix?

On several of the ILS and RNAV LPV approaches in my area (and notably the ones I expect for my checkride), I consistently intercept the GS at 0.1-0.2nm before the FAF. An example: I am flying at ...
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?
8
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2answers
701 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 ...
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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4answers
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If you were to fly an ILS in a knife edge would you receve GS and LOC be flipped?

because LOC and GS work the same way, if you were to fly one at 90 degrees bank would your information be displayed on the wrong indicators?
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 ...
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 ...
7
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2answers
10k 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 ...
7
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2answers
2k views

When and how do I align with the runway during an offset ILS approach?

In X-Plane 11, when landing an A330 on 04R at Nice (LFMN) on an ILS approach, the aircraft is brought perfectly to the end of the runway but because this is an offset ILS the aircraft is at about 2° ...
7
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2answers
982 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 ...
7
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2answers
8k views

Which airports have ILS Cat IIIC?

Are there any airports with ILS working CATIIIC? What do the charts for this procedure look like? Is there a missed approach procedure?
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 ...
7
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1answer
2k views

How much does an ILS approach cost?

A statement in this question, asking how to pay fees for using the airport services, without being at the airport, inspires me to ask a question. Quote: (Yeah I know... you gotta pay for an ILS ...
6
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3answers
612 views

If cleared for an ILS approach at the Initial Approach Fix, where should I intercept the glideslope?

I am a brand new Instrument Pilot and the answer that I am looking for is related to good technique and not necessarily not what is legal or not. My instructor taught me that when flying an approach ...
6
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1answer
544 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 ...
6
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1answer
1k views

Why are the minimums between these two ILS instrument approaches to the same runway so different?

The minimums for the Van Nuys ILS Z Rwy 16R are 1095/40. The minimums for the Van Nuys ILS Y Rwy 16R are 1461-1 1/2. Question: Why are the minimums for the ILS Z so much lower than the minimums for ...
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 ...
6
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3answers
597 views

How is an ILS approach conducted when following a heavy aircraft?

I'm following a much heavier aircraft on an ILS approach to a large airport. Ideally I'd like to stay a bit above the glide path and land late, both to avoid the turbulence and also get off the ...