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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3answers
164 views

How do I know which airports have ILS and for which runways?

I have been into flying for years but something I can't figure out is how do I, as a pilot, know if an airport I am going to has ILS, which runways would have it and why do only some have it but the ...
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2answers
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Why is the ILS16 approach at KSKF not available in my Garmin 430W?

I am doing flight instruction on the San Antonio area (Texas) and I've been shooting different approches on the vecinity airports. One of the approaches I usually execute is the ILS 16 at KSKF, which ...
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2answers
108 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?
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Why is the ILS 36R approach at ZBAA over twice as long as a standard ILS approach?

I fly exclusively in a consumer flight simulator, so excuse me if there's an obvious answer to this. ILS approach plates typically show a long, arrow-like symbol to indicate the part of an approach ...
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2answers
460 views

How to choose the right ILS when the runway has more than one?

I'm wondering how is the right choose when an runway has ILS x, Y, Z. What should I consider in order to pick one of those for landing?
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1answer
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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.
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56 views

How big does an object in one of the ILS critical areas have to be to cause a problem?

ILS installations have a critical area extending some distance back from the glideslope antenna (primarily due to most glideslope transmitters’ needing to bounce one of their two beams off the ground ...
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2answers
232 views

How do I follow an ILS glideslope on the ADI in Falcon BMS?

I'm currently flying the ILS landing mission in Falcon BMS, I'm practicing landing using the instruments (head down) and although I'm mostly OK with the LOC, I struggle to maintain a 2.5 degree ...
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1answer
122 views

Why do the GS and LOC indicators blink?

So, the question is in the title. Specifically referring to this video. At around timestamp 2:10 in the video, you can see the GS and LOC indicators blink. Why does it blink?
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Are ILS CAT IIIA minimums based on the radar altimeter or on barometric altitude? [duplicate]

From what I understand the CAT II ILS minimums on the far right are based on radar altimeter 102'AGL and barometric altitude DA(H) 429'MSL (100'ATL). But what about the CAT IIIA minimums in the ...
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1answer
130 views

How many African countries currently deploy Cat 3 ILS? [duplicate]

How many countries in Africa currently operate Cat 3 ILS?
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31 views

What is considered to be a approved deviation in an ILS beam during a CAT3 approach?

For category 3 approaches, the airport has to transition to LVP mode. In this mode- the holding points are taken back a little bit and the runway surroundings are clear. My question is- Is there a ...
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1answer
99 views

Why are Category II ILS approaches prohibited in an E-Jet with inoperative pitch trim?

Part of the Pitch Trim Runaway checklist for the E-Jet family states that Category II ILS approaches are prohibited if neither pitch trim channel is available: If both pitch trim channels are failed: ...
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1answer
239 views

How often is ILS accuracy checked?

I imagine checking ILS accuracy by measuring ILS signals at various points along the approach path is routine maintenance, although I don't know how it is done. How often must this kind of check be ...
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2answers
109 views

With current technology, why is there still increased separation between aircraft and delays in low visibility conditions?

Since most (if not all) commercial aircraft are equipped with inertial and satellite/GPS navigation, why is increased separation between aircraft necessary? Can't controllers immediately identify the ...
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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?
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1answer
2k views

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

Is there a list of airports with category 3 Instrument Landing Systems?
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1answer
366 views

Can you continue an ILS approach when weather falls below minimum?

If, after passing the final approach fix, weather deteriorates so that the reported values are now below required minima, is it allowed to continue the approach?
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48 views

What is the difference in purpose of the 1:40 Obstacle Identification Surface and the 1:50 clearance plane for an ILS glideslope?

I have found references to the Obstacle Identification Surface (OIS), which is approximately a 152ft/NM slope from the end of the runway (1.43 degrees, 1:40 rise/run) and a 1:50 clearance plane noted ...
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2answers
204 views

Distance to the runway/ touchdown point

Trying to learn about aviation, and looking through all the displays in the cockpit, and also the Garmin G1000, I am not sure where I see the distance to the runway touchdown point, or the start of ...
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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 ...
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0answers
48 views

Is ILS secured from being hacked/overriden/disturbed? [duplicate]

Since ILS uses radio frequency. Then is it possible that some one transmit a malicious signal on the same frequency ? Are there any measures to prevent that ?
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1answer
562 views

How is the center ILS used on the 747-400?

The aircraft has 3 ILS receivers, but only ILS L and R in the CDUs. How does the ILS C is put into action?
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258 views

Reason for the multiple sidelobes in an ILS glideslope signal

Why are there multiple side lobes in the glide slope signal from an ILS?
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1answer
2k 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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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?
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681 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) ...
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2answers
1k 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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665 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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1answer
370 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
290 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
49 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.
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1answer
482 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 ...
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1answer
568 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
211 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
895 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 ...
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1answer
281 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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4answers
578 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
403 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.
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1answer
2k 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, ...
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1answer
998 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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2answers
1k 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
141 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
410 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
715 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 22L....
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3answers
421 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
378 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
219 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
243 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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3answers
679 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?