Talk:Instrument landing system

message: This table is of little use as it is extremely confusing.  It seems to combine regulations from 3 authorities (ICAO, FAA, JAA) without distinguishing between them.  Imperial and metric measurements are mixed although they are not equivalent (row 1: 550 m = 1804 ft, not 2400) and other values lack clarification (row 1: when is the Canadian visibility minimum 1600 ft and when 1200 ft?).  I would have split the table into 3 - one for each authority - but could not decipher it, not even with the aid of the references given (some of which seem to be irrelevant to this particular subject). 
Max Szabó  — Preceding unsigned comment added by 109.84.0.177 (talk) 17:28, 1 December 2013 (UTC)
thread_title: ILS Categories table

message: ILS was instrumental in the crash of an Avianca 747 in Madrid in 1983. Can someone explain why? 
Antonio ILS dummy Martin
:Read Here: 
*The Avianca 747 did not follow the published procedure and attempted to intercept the ILS on an incorrect track. At the same time the aircraft descended below the published minimum safe altitude. A GPWS warning was received but ignored. (Crewroom mythology has it that the Captain responded to the call "Pull Up!" with "Shut Up Gringo!"). The aircraft hit a ridge to the north-west of the airfield and was destroyed. The radar controller did not advise the aircraft that it was out of position and the approach may not have been monitored on radar. The aircraft did not intercept the ILS so the ILS was not directly involved. Treesmill 08:17, 6 October 2005 (UTC)
thread_title: ILS related aircraft accidents

message: ILS is said to be particularly susceptible to interference from faulty FM broadcast transmitters as the latter tends to utilise relatively high power levels on nearby frequency ranges. Does this merit some mention in the article ? How widespread a problem is it ? 90.198.231.12 (talk) 22:25, 26 January 2015 (UTC)
thread_title: Susceptibility to radio interference

message: Some major airports swithces the landing directions in the same runway frequently - that is from opposite directions. How is this achieved? There might be two sets of ILS and other related instruments fixed thre?   —The preceding unsigned comment was added by 213.42.2.26 (talk • contribs) SPJ   June 20, 2006.
:Dubai apparently only has 1 ILS, but Abu Dhabi International has ILS equipment on both runway ends, runway 13 and runway 31 are the same runway. This requires two separate systems, so 2 localizers and 2 glideslopes and according to the approach plates, at Abu Dhabi two Middle markers. Both procedures appear to use the same VORDME though. For safety the Glideslopes and localizers are normally interlocked so that they are not on at the same time. Sometimes they even operate on the same frequency making interlock even more important. The ones at Abu Dhabi are different frequencies, but only one would be on at a time to prevent misleading signals resulting in aircraft landing at both ends of the same runway. --Dual Freq 11:19, 20 June 2006 (UTC)
thread_title:  Landing from both directions 

message: This article is getting way too technical for the average wikipedia reader to understand. I've made some adjustments, but the tech portion might need to go to the end and a 'lighter and fluffier' section should probably lead off the article. None of the article is sourced, and the tech stuff is likely to only be found in a Wilcox or Thales tech manual. I'm not sure how any of it's going to be available to a non-pilot / ILS tech. --Dual Freq 23:44, 1 January 2006 (UTC)
replies: text: Sorry for the reduction in size of your image. The size was so that the images wouldn't dominate the page and people could click the image to see the full size. I captioned it with the part that was beneath it and said above is etc.... However, based on my experience with ILS maintenance, I'm not sure I can agree with the way the 90/150 overlap in the image. For the purpose of a simplified overview maybe the image is OK. However, the second image, (which I didn't create), is unlabeled, but shows the simplified/ideal pattern of a dual frequency localizer. The long main lobe that has a dotted line is from the reference transmitter Carrier and Sideband (aka CSB) pattern. This signal has a maximum strength on centerline and each antenna is fed in phase with each other. The sideband only (aka SBO) pattern is shown inside of the dotted lines and properly illustrates a signal fed to two antennas 180° out of phase. Ideally the null or minimum of the sideband pattern would fall on the centerline of the runway. Most ILS theory books would probably stop with this narrow part of the pattern because it is taught using a standard, single frequency set up. The second, shorter and wider pattern, only complicates the picture. It is meant to display the signal from a dual frequency system's clearance transmitter. As for the clearance signal theory, I'm not certain I can explain it in detail from memory, but basically a second frequency is used to reduce reflections from hangers and other stuff that is outside of 10°. It also removes the 'low clearance' points in the pattern so that the user gets full scale deflection on their ILS display while outside of the localizer course. The second frequency is so close that it falls into the bandwidth of the aircraft receiver. When the aircraft enters the area where the clearance signal is stronger than the reference signal, the receiver 'captures' the second frequency and uses that signal, which is full scale fly right or fly left.--Dual Freq 00:01, 4 January 2006 (UTC)
replies: text: First it is important to remember that the lobes shown in my diagram are not the boundaries of the signals. They are contours which illustrate the locus of points at which the power of that signal is at a particular level. It would be possible to choose a power level at which the lobes did not overlap, but this would give a misleading impression because the signals in space must overlap, otherwise the DDM would change suddenly across the centreline instead of being proportional to deviation as required. I am aware of the existence and purpose of the clearance signal, but in my view it is not a necessary part of a 'principle of operation' explanation. To include it a much more complicated explanation would be needed to account for the need for such a signal and how it achieves the required result and this would add nothing to the understanding of the principle of operation. treesmill 11:33, 4 January 2006 (UTC)

text: As for the phase of the 90 and 150, I didn't add that either, but I think it refers to what is called 'modulation equality'. Ideally you want the reference transmitter to transmit mod equality, meaning the 90 and 150 are equal in amplitude yielding 0 difference in depth of modulation (DDM) or 0 micro amps of deflection on an ILS instrument. About the only thing you can do is adjust the starting phase of the 90 and 150 signals. If your array or location are not perfect (and none are) you may have to increase the amplitude of the 90 or 150 signal to move the course signal to centerline. --Dual Freq 00:01, 4 January 2006 (UTC)
replies: text: Adjusting the relative phase of the 90 and 150 signals will not affect the position of the 0 DDM locus, because the relative phase of those signals is changing continuously and rapidly (about 30 rad/s) anyway. As you say, adjustment of relative amplitude is all that is available. treesmill 11:33, 4 January 2006 (UTC)
thread_title: Technical

message: Explain the use of the word promulgated under 'marker beacons' - even knowing the definition of the word, its use clarifies nothing - how is the height promulgated?  —Preceding unsigned comment added by 81.158.108.46 (talk) 23:22, 28 October 2007 (UTC)
replies: text: The use of marker beacons and their placement on the glideslope is determined by the operator of the airport as well as local geographical constraints. There is no set in concrete position data for every marker beacon location (except they need to be coincident with the localiser/gp centreline). Therefore it is difficult to give you an exact place for a beacon. There is an outer and middle and sometimes an inner marker, that's about as far as it goes for "usual situations".--Read-write-services 03:16, 29 October 2007 (UTC)
thread_title:  Marker Beacons 

message: I have reorganized the article a bit, and removed some of my previous edits that were questioned above. I hope this helps things. I'm not sure I could do the tech section properly, so I've left it out for now. --Dual Freq 02:05, 24 January 2006 (UTC)
thread_title: Reorganization of article

message: Added a minor reference to HUD and also clarified "autoland" to be coupled to a Flight Control Computer but a manually flow approach using a HUD can also be used. As an aside some companies make both Head Down and Head Up Displays and also autoland systems.  In a sense this puts the HUD group (less stuff to maintain so lower cost, less safety concerns from computer failures, so lower cost) in direct competetion to the Autoland group (more precise, better passenger comfort, etc.) - Brian (ZazenCID 22:51, 31 May 2007 (UTC)
thread_title:  Add Head Up Display to "Use of the ILS" 

message: FAA Notice 8200.97 (Airman and Aircraft Approval for Reduced Visibility Flight Operations, dated 9/20/06) and its contents are incorporated into section 7 of Order 8400.10, Chapter 2, All-Weather Terminal Area Operations via N 8000.340 (which contains the new material for 8400.10) effective 12/12/06.  And contrary to what is on the first page of this Notice, all Notices are effective until specifically canceled by another notice.  <sigh>  - Brian (ZazenCID 16:37, 1 June 2007 (UTC)
thread_title:  Add Reference to FAA Order 8400.10 All Weather Operations 

message: so which one of you experts knows the components of SCS-51 (set complete system)? Brian in denver (talk) 18:16, 3 October 2009 (UTC)
thread_title: SCS-51

message: Folks, I found a small article on the US experiments on the radio landing aids during heavy weather and fog in a 1931 issue of Popular Mechanics.  I put it in as a reference.  But something I think is wrong with the dates.  One sentence says the FAA authorized six installation in 1941 and then the next sentence says the first commercial aircraft to use radio landing aid was in 1938???? Jack Jackehammond (talk) 07:57, 29 November 2010 (UTC)
thread_title:  Problem with year date in [[Instrument landing system#History|History Section]] 

message: I've removed the section below from the article. It's probably too technical for the place it had in the article, and it looks mostly like a set of specifications copied from somewhere. I don't know if the article really needs this information but perhaps someone can rewrite it and integrate it in the article. Rpvdk (talk) 15:15, 2 June 2011 (UTC)
replies: text: Some of it is not pertinent, however, the coverage is something that should perhaps be left in.  Coverage and reliability of the signal are better explained with a diagram, though - the one in the Canadian AIM would be good but I don't know its copyright situation.  It's under | COM 3.13.2.HiFlyChick (talk) 03:06, 3 June 2011 (UTC)
thread_title:  Overly technical info early in article 

message: At the time of writing this comment, there is a scan of a Jeppesen approach plate for KLAX ILS 24L on the article.  At the bottom is clearly seen a copyright assertion by Jeppesen, but someone else is claiming copyright on it and releasing it under Creative Commons.  Does that person legally represent Jeppesen, or should this be removed? MSK (talk) 05:52, 6 January 2012 (UTC)
thread_title: Approach Plate Example

message: Several other articles have been tagged for merging here, although the editor has not as yet tagged this article as their destination, so other editors may not be aware.#
=== Space modulation ===
* oppose - It's a radio engineering principle, not an end product. Andy Dingley (talk) 11:36, 2 May 2012 (UTC)
replies: text: *I wouldn't say it's similar to one of the components - it is one of the components.  If glideslope indication is lost while shooting the ILS, you continue the same approach with no changes other than using the higher minima of the localizer (only) approach.  While I agree that it has its own use, it's generally installed instead of an ILS because the constant glidepath profile won't meet the obstacle clearance requirements, so a stepdown profile is needed.  That would be something that could also be mentioned in the ILS article i.e. "...When the obstacle clearance requirements of an ILS can't be met, only the localizer portion of the ILS is installed..." HiFlyChick (talk) 07:29, 7 April 2013 (UTC)
thread_title:  Multiple merges 

message: * oppose - It's a radio engineering principle, not an end product. Andy Dingley (talk) 11:36, 2 May 2012 (UTC)
thread_title:  [[Space modulation]] 

message: * oppose A distinct component with plenty of available sourcing. There is no reason to or benefit from merging this. Andy Dingley (talk) 11:36, 2 May 2012 (UTC)
replies: text: *I wouldn't say it's similar to one of the components - it is one of the components.  If glideslope indication is lost while shooting the ILS, you continue the same approach with no changes other than using the higher minima of the localizer (only) approach.  While I agree that it has its own use, it's generally installed instead of an ILS because the constant glidepath profile won't meet the obstacle clearance requirements, so a stepdown profile is needed.  That would be something that could also be mentioned in the ILS article i.e. "...When the obstacle clearance requirements of an ILS can't be met, only the localizer portion of the ILS is installed..." HiFlyChick (talk) 07:29, 7 April 2013 (UTC)
thread_title:  [[Localizer]] 

message: I have removed the merger templates from the aforementioned articles. The consensus result of the discussions above was: no merger. Finnusertop (talk | guestbook | contribs) 10:57, 6 August 2014 (UTC)
thread_title:  Merger discussions closed 

message: I am sorry but this table is misleading if I am interpreting it correctly. It infers that the ILS is tuned by the pilot via the X or Y channel number. The ILS is tuned via the VHF LOC frequency with (as it says elsewhere) the g/s receiver being tuned automatically depending on the VHF LOC frequency. You will not see an ILS primarily highlighted by a X/Y channel on a plate - only the X/Y channel being referred to for the associated DME (if any) and is primarily a military thing. The X or Y channels refer to the associated DME (if any) and, on civilian aircraft, the X or Y channel is not usually referred to directly as the aircraft DME interrogator relies on the LOC frequency being passed to it by the ILS (Loc or integrated LOC/GP) receiver, the VHF R-AID tuning panel itself or directed navigation device by a variety of methods (either usually digital ARINC standards or using monitored tuning discretes.). The DME unit will then use a look-up table, algorithm or some other method to determine the actual RF frequencies to use to lock to the DME ground unit.  I would suggest that this table needs re-organizing so that the VHF LOC frequency is in the left-most column, the G/P UHF frequency is in the next column (but it is of little value as the tuning of the G/P is transparent to the pilot so this column could be got rid of altogether) and the associated DME X/Y channel being the right-most channel. Longfinal (talk) 11:17, 7 April 2013 (UTC)
thread_title:  Frequency list 

message: Another point which may have been made but I cannot see it: If there is an associated DME with an ILS, the idents of the LOC and the DME are interlaced so that there are 4 (I think) LOC idents on the VHF LOC frequency followed by one DME ident on the DME ground to air frequency (on a higher audio frequency than the LOC ident too). In that way, if the pilot is listening to the audio from both the LOC and the DME on the aircraft cockpit integrated audio system, he/she can determine if either facility is a) available and b) associated with the other one. It is also becoming more common to prefix ILS callsigns with "I" followed by a pause to avoid confusion with other similar R-AID callsigns. See ICAO Annex 10 for most of the above. I hope that helps.Longfinal (talk) 11:17, 7 April 2013 (UTC)
thread_title:  Identifying a station 

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thread_title:  External links modified 

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thread_title:  External links modified (January 2018) 

message: An editor has reverted the lead multiple times to what (may be hair-splitting by me), seems incorrect. However, as I teach the subject, I feel that it needs clarification beyond my "verbose", description. There is an incorrect assertion that the ILS lands the aircraft when the pilot has no visual contact with the runway-this is incorrect, firstly, the Pilot flys the aircaft and lands it!, secondly, depending upon the catergory, the pilot MUST have visual contact with the runway to be able to land the aircraft. I'm a bit rusty on the avionics side of the system (aircraft electronics), however, I am quite clear on the ground systems operation. A cat IIIc system is able to assist the pilot using an autoland procedure which is a hands-off landing. however, there are few of these installations around the world, by far the most common is a cat I system which the pilot must have visual contact with the runway at a distance of 850 Metres (runway visual Range), and an altitude of 60 Metres (Decision Height) BEFORE landing the aircraft. I am appealing to whoever wishes to edit/correct this to do so, as the current information is misleading at best. I wont do this for the moment as it may appear to be a conflict of interest as i'm bringing it up, but unless someone more qualified than me rectifies/clarifies the information, I'll revert/fix the description sometime soon. 
Cheers,
Read-write-services (talk) 23:43, 4 February 2018 (UTC)
replies: text: I guess you're referring to your recent edit, which I reverted primarily because it changed "enables" to "assists". Clearly it would be incorrect to imply that all ILS landings are Cat IIIc automated landings, and I don't read the lead as suggesting they are. The ILS does indeed "enable" a landing in the sense that if the pilots are unable to establish a visual approach, it it would be both dangerous and illegal to continue without some sort of IAP. I realise the edit was aimed at explaining different minima for different categories, but the distinction it was trying to convey wasn't clear, and these details are covered in the article. Burninthruthesky (talk) 21:25, 5 February 2018 (UTC)

text: Before that: an IFR flight MUST not descend below Minimum safe altitude unless the pilots are approaching to land, for which they need either visual contact, or an instrument approach procedure. I see your point about "enables aircraft to land". How about something like, "An instrument landing system (ILS) enables pilots to conduct an instrument approach to landing if they are unable to establish visual contact with the runway."? Burninthruthesky (talk) 05:59, 6 February 2018 (UTC)

text: Thank you for raising the discussion, it highlights an interesting misnomer I hadn't considered. I've only ever really thought of an ILS as an approach procedure, rather than a "landing system". I've put in the agreed suggestion for now. Maybe it will be improved further at some point. Burninthruthesky (talk) 08:13, 7 February 2018 (UTC)
thread_title:  Article lead-in needs work/reversion 

message: among the listed manufacturers only Thales and Indra are actual active ILS manufacturers. We may add to the list Intelscan, Selex (Leonardo Group) recently acquired by Indra, or Mopiens (South Korea). 2001:B07:5D37:ED3C:FF57:7EE7:C581:7ABF (talk) 19:29, 10 October 2023 (UTC)
thread_title:  Market