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.

Filter by
Sorted by
Tagged with
6
votes
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 ...
3
votes
2answers
2k 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 (...
3
votes
0answers
145 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 ...
5
votes
4answers
481 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 ...
5
votes
1answer
897 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....
3
votes
3answers
479 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. ...
5
votes
1answer
413 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 ...
2
votes
1answer
236 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.
1
vote
1answer
305 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 ...
3
votes
3answers
748 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?
3
votes
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?
0
votes
1answer
223 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 ...
2
votes
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 ...
7
votes
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° ...
13
votes
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 ...
4
votes
1answer
1k 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 ...
3
votes
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?
7
votes
1answer
7k 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 ...
2
votes
1answer
9k 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 ...
24
votes
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 ...
4
votes
1answer
4k views

How are the frequency pairings for localizer and glideslope decided?

How are the frequency pairings for localizer and glideslope decided?
7
votes
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 ...
3
votes
3answers
850 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 ...
6
votes
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
votes
3answers
598 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 ...
6
votes
1answer
539 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?
7
votes
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 ...
1
vote
1answer
2k 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
votes
1answer
455 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, ...
11
votes
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 ...
5
votes
3answers
1k 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,...
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 ...
10
votes
2answers
5k 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'...
9
votes
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 ...
5
votes
1answer
952 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....
3
votes
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 ...
6
votes
1answer
285 views

What is ILS 114 / 162 / 294?

I am searching for airports that have ILS (not sure if there is a "law" that any airport servicing civil flights must have one). So I googled around and found this nice site http://www....
4
votes
1answer
884 views

What is the ILS glide slope deviation on a 4 degree VOR check error?

On a US IFR flight, it is required to do a VOR check every 30 days and the error tolerance is 4 degree except for airborne check. Suppose I have 4 degree error on my VOR check. When I fly an ILS and ...
7
votes
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
votes
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 ...
12
votes
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 ...
3
votes
1answer
1k views

Does ATC provide ILS frequency and course setting for the runway in use?

I'm just from FSX background and not familiar with real procedures. In real world situations, when the pilot is vectored to the runway, does the ATC provide the pilot with the runway frequency and ...
4
votes
1answer
744 views

(See Included ILS Chart) What to Do After SMT RDL 084?

Below is a screen grab from the ILS RWY 25R approach chart for HKG/VHHH. What should the plane do after passing SMT radial 084 (or TD D8 NM)? It doesn't look like immediately turn heading 253 degrees;...
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 ...
7
votes
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 ...
9
votes
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 ...
12
votes
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, ...
14
votes
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
votes
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 ...
2
votes
2answers
795 views

Can the ILS be shut down? [closed]

Can the ILS be manually turned off? Not by the pilots inside the cockpit by simply shutting of the ILS button, but rather by a 3rd party personnel, such as an ATC or a ground crew member. ATC shuts ...