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Questions tagged [ils]

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

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2answers
86 views

Why are there no RNAV (ILS) approaches?

While studying the PBN (FAA Order 8260.58A) and TERPS (FAA order 8260.3D) documents, I still have some trouble figuring part of the logic behind the naming and definitions of the published IAP Charts. ...
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2answers
508 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 ...
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0answers
132 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 ...
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1answer
52 views

Can I execute an ILS approach using a NAV CDI with LOC signal only?

I have been flying a small Cessna airplane that has a COM/NAV NARCO MK12 equipment with CDI (lateral needle only). This CDI does not incorporate a horizontal needle to provide vertical guidance, so ...
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1answer
35 views

Has mod percent changed for Mark-1 glide slopes?

Mark-1F glide slopes operate at 80 percent modulation. What was it for earlier versions i. e. Mark-1C, Mark-1D, etc.
6
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1answer
369 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 ...
4
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1answer
141 views

Is the callout “minimums” on the 737 used to describe DH on precision approaches

So, I have heard that decision height (DH) is used to signify the height on a precision approach which the pilot has to decide whether to continue or not. But, in the 737, I only hear "approaching ...
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1answer
99 views

Does the glide slope flag detect percent of modulation (80%)?

Please advise if the glideslope flag validates that the received frequency is being modulated at nominal 80% or 40% for a localizer.
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2answers
152 views

What does ''NAV ILS OUT OF SERVICE'' mean?

Just curious about the NOTAM below: !SMF 01/045 (KSMF A0080/19) SMF NAV ILS RWY 16L OUT OF SERVICE 1901180419-1901262359 Does that mean only the glideslope is broken so we can still do a LOC ...
3
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1answer
177 views

Do Instrument Landing Systems restrict building heights and can these be overcome?

A recent territorial spat between the countries Malaysia and Singapore over an ILS implementation made me curious. I'm interested in finding out about ILS and how an implementation of one would affect ...
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3answers
238 views

Do any aircraft have a “self-contained ILS”?

The ILS is an invaluable aid to pilots, especially those operating to/from the many airports where poor weather is common (low-visibility operations would be completely impossible without an ILS); ...
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1answer
183 views

Does ATC prefer ILS over RNAV?

Listening to APP for several major (US class B) airports, it seems that every flight is vectored to intercept the localizer. Is it really possible that 100% of flights filed an ILS approach? If so, ...
4
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1answer
535 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 ...
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1answer
237 views

How to calculate DDM in a ILS dual frequency system?

I'm working in a project where I have to process ILS baseband signals. I have no problem obtaining DDM value from single frequency signals, nor the individual components of a dual frequency signal (...
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0answers
110 views

Diversions because of fog: What are the reasons?

It's fog season again around my local airport MUC (EDDM), and I have noticed a number of diversions recently. Some planes were holding a bit before attempting to land, performed a go around and then ...
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4answers
234 views

Do different planes (category) aim differently in the 'final stages before flaring'?

(youtube.com) Do different planes (categories A through D) aim differently in the final stages before flaring? I'm asking about precision runways. The reasons I ask: An ILS' glide slope is not ...
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1answer
355 views

Why wouldn't KJFK offer the ILS for 22L?

(Source: Flightradar24) The above was from last Sunday around 17z. I was watching FR24 with the ATC feed. The airport was operating in 'arrival priority' with approaches to both 13L (Canarsie) and ...
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3answers
289 views

Why is there no instrument taxi system for low-visibility operations?

In one of the comments on this answer regarding ILS category IIIc operations (or, rather, the lack thereof), it's mentioned that There is no [radio] guidance for taxiing except the pilot's vision. ...
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1answer
210 views

What is the reference plane for the ILS glideslope angle?

Is a 3-degree glideslope based from the runway surface slope at the point where the antenna is installed or is it referenced to a zero-degree plane? If you know of a design document or FAR/AIM ...
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1answer
87 views

What are the procedures for flight checking a glideslope and localizer?

What are the FAA and ICAO requirements and procedures for flight checks and calibration of glideslope and localizer transmitters? I'm interested in both the engineering and piloting aspects.
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1answer
145 views

How the Log Periodic Dipole Antenna of Localiser help in varying modulation depth?

Here Albert Helfrick speaks about 40% modulation depth for each tone in a localiser radio signal. However latest manuals of ILS manufacturers and google source speaks about 20% modulation depth, not ...
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188 views

What is space modulation? Its application is instrument landing systems [duplicate]

How the modulation depth changes with respect to azimuth for the Receiver of aircraft when it is using localiser or glideslope?
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3answers
431 views

Why are the modulation depths of the localiser and glideslope different?

Why do we use a modulation depth of 20% (for 90Hz and 150Hz each) in the case of the localiser and 40% (for 90Hz and 150Hz each) in the case of the glideslope? Why not use 20% for both?
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1answer
573 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?
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1answer
203 views

Do LED lights work well for CAT III B operations?

Does any airport equipped with LED lights for all the CATIII B Components? If so, is there any history that it caused difficulty in aircraft operations? We are planning to install our new runway with ...
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2answers
552 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 ...
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2answers
609 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° ...
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2answers
2k 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 ...
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1answer
520 views

What are the differences between each ILS category?

I want to know the characteristics of the different categories of Instrument Landing System (ILS): CAT I, CAT II, CAT IIIa, CAT IIIb and CAT IIIc. What are the differences between them? (This ...
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2answers
778 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?
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1answer
3k 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 ...
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1answer
4k views

How and where is the ILS Glide Slope DDM to dots conversion defined?

The Instrument Landing System (ILS) gives output in terms of Difference in Depth of Modulation (DDM) to the avionics. But all display uses dots, also TAWS system definitions also uses dots as ...
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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 ...
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1answer
2k views

How are the frequency pairings for localizer and glideslope decided?

How are the frequency pairings for localizer and glideslope decided?
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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 ...
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3answers
370 views

Why is an approach that relies on both LOC and PAPI not considered a precision approach?

I am an aviation layman. I am reading about PAPI lighting system and it seems like it provides vertical guidance, just like the glideslope component of an ILS. Coupled with a LOC, both vertical and ...
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1answer
2k 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 ...
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3answers
418 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 ...
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1answer
377 views

On an inverted aircraft, is the ILS glide slope sensing reversed?

If I'm halfway through a barrel roll on final descent, on an ILS, will I get reverse sensing on my glide slope indicator?
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1answer
976 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 ...
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1answer
876 views

Where to find information on ILS categories at European airports?

I have a list of airports in Europe and I need to find up-to-date information about ILS categories (I, II, IIIa, IIIb or IIIc) at these airports. Does anyone know where I could find such data ...
5
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1answer
245 views

Why are the minima for Cat A higher than for other categories at KSEA ILS 16L?

I was looking at the KSEA ILS 16L approach (depicted below) and was wondering just why the minima are bumped up for Cat A aircraft (64 feet on both DA and HAT, as well as 200 feet of RVR). Thing is, ...
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1answer
5k 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 ...
4
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3answers
660 views

Can a pilot transition from a localizer approach to an ILS approach?

I was recently looking at the approach to RWY 8L at Honolulu, Hawaii (PHNL). Looking at the approach IAFs, I see the LOC RWY 8L approach has many different options, and has an intercept altitude at 2,...
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0answers
248 views

Why is my Garmin GFC 700 wandering a lot laterally on an ILS approach?

I've noticed that my Garmin GFC 700 autopilot is 'hunting' on ILS approaches. To be absolutely clear, I mean an approach using a localizer with glideslope. It is rock solid on RNAV, GPS, and other ...
4
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1answer
11k 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 ...
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1answer
2k views

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'...
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3answers
2k 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 ...
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1answer
573 views

What are outer marker horizontal dimensions at 3 degrees ILS path?

What is the outer marker "distance" along the flight path of a 3 degree ILS? I provide my two approaches below, but as they contradict each other, I am asking this question to learn the proper answer....
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4answers
6k 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 ...