Talk:Microwave landing system

Cleanup

I've cleaned up the article a bit. It looks like it was originally a cut and paste from the FAA Aeronautical Information Manual, which I have included as a reference. --Dual Freq 03:52, 2 March 2006 (UTC)

Where concerns over the availability of GPS continue to be an issue

In Europe, concerns over the availability of GPS continue to be an issue? Where do you get this information. Europe has the same view of the sky as the rest of the world.

Greater Accuracy

Greater accuracy than ILS? Please Cite and qualify that. IFP Inventory shows only 3 MLS approaches in the USA and 100 CAT III ILS. How is MLS more accurate than CAT III ILS? I'm certain there are advantages of MLS over ILS, and I know about the installations in the UK, but you should qualify the accuracy statement and cite if possible. Thanks. --Dual Freq 22:45, 15 May 2006 (UTC)

accuracy

MLS CatIII has not been proved yet, I added a figure to show the multipath effect that happens as the aircraft approaches the airport, it will receive multi path coming from all the hangars . the system is designed with angle limitations so you can try to avoid mountains...but it is hard to avoid any constructions or other aircraft around the airport. note that it has been tested on aircraft carrier with many multipath coming from the sea and other aircrafts around. GPS CatIII is not proved as well, so the ILS remain the only system for landing without visibility —The preceding unsigned comment was added by User:Bloublou (talk • contribs) .

Limitations

MLS system is sensitive to multipath. as the signal reflects on hangars, it can create an error in the aircraft position.

Thanks for adding the multipath image, but I was under the impression that MLS was the solution to the multipath problems of ILS. If there are severe multipath problems with MLS too then why is MLS the solution to ILS's problems. Why is the UK installing MLS systems to solve ILS multipath and ILS critical area hold problems?[1] Please cite a source for the MLS multipath problems and indicate their severity. Thanks. Dual Freq 00:23, 4 August 2006 (UTC)

See also: "MLS, on the other hand, was immune to multipath.", MLS: Back to the Future?. Avionics Today. April 1, 2003 Dual Freq 00:27, 4 August 2006 (UTC)

Certification

[2] In this article they explain MLS has been certified for landing in Cat IIIb for British Airways in 2007 This means it will probably be operationnal on London Heathrow

Do pilots need a specific certification for that? —Preceding unsigned comment added by Bloublou (talk • contribs) 13:42, 29 September 2008 (UTC)

Limitations

I have read those articles and a lot more...but I have been working on MLS systems for years and have patent on signal processing to avoid the multipath effect...then I can say the people who wrote the article may not have work on it. As I try to explain on the diagram, the beam reflects on a building and goes to the aircraft, this is clear to me, and there is no way to avoid it. the thing is that it appears sometimes that the fading is greater on the direct way, so the both beam as seen from the aircraft have the same amplitude...and then nobody can say which one is the good one. UK is installing MLS because they think it is better, it is in certain ways, but has its limitations. Some patented algorithms may limit this phenomenom, and maybe they are happy with it, but I don't think they already land in CatIII with it. have a look at http://adsabs.harvard.edu/abs/1977uva..rept.....M http://www.fas.org/nuke/intro/aircraft/facilities.htm http://www.au.af.mil/au/2025/volume3/chap13/v3c13-5.htm http://www.freepatentsonline.com/5627546.html --bloublou 17:02, 6 August 2006 (UTC)

in the article "MLS, on the other hand, was immune to multipath."

Where is the demonstration that MLS is immune to multipath ?—The preceding unsigned comment was added by User:Bloublou (talk • contribs) .

FRS-2001 published by US DOT and US DOD says, "The MLS signals are generally less sensitive than ILS signals to the effects of snow, vegetation, terrain, structures, and taxiing aircraft" and "No ambiguity is possible for the azimuth or elevation signals. Only a very small probability for ambiguity exists for the range signals and then only for multipath interference caused by moving reflectors." The whole point of MLS was to solve the limitations of ILS, if MLS is fatally susceptible to Multi-path then what is the point of installing it. Several articles in aviation publications indicate a resurgence of installation of MLS. Why would these be installed for only Cat I purposes. I don't have access to terminal charts for Europe, but according to the above article Heathrow has MLS as does Charles de Gaulle, Frankfort. Dual Freq 11:29, 9 August 2006 (UTC)

Snow, vegetation, terrain...sure it is better, because you won't have multi reflexions, only one at a time. Structures, and taxiing aircraft..sure it is not, and this is just physics, reflection against any wall will come to the incoming airplane and create 2 sidelobes with no way to know which one is the wrong one. If people want to believe in DOD rather than physics, then fine for me... --bloublou 22:07, 9 August 2006 (UTC)

If you would like to add a limitations section that explains that this is a minor limitation that it has been corrected via algorithms and/or the application of siting criteria that takes it into consideration, then go ahead. However, I have to assume that flight inspection aircraft would detect this problem prior to the commissioning of a new installation and the system would be restricted to prevent the problem. I think that the biggest limitations of MLS are: it isn't installed anywhere, most US installations have been decommissioned and it's not GPS. If you still want to add a section, use more than one sentence and please cite it with something verifiable. Thanks. Dual Freq 23:20, 9 August 2006 (UTC)

Have corrected the link to the Aviation Today link. It now points to the article in the magazines archive section. The previous link was to the News Page. RichardABrown 18:12, 6 March 2007 (UTC)

Research Documentation

In case someone wants to talk about how this lovely thing worked, I produced the documentation set (while cat-herding the software and hardware docs); this work was produced to the Canadian Federal equivalent of "MIL-SPEC" i.e. DFS-1002. The end product was 3 volume. A comprehensive "Executive Summary", an exhaustive user's manual (probably 200+ pages) and a humungous installation / testing volume (750+ pages).
p.s. it was also scheduled for deployment at Toronto Island
--BenTremblay (talk) 23:26, 6 July 2010 (UTC)

Future

commenting on MLS is Dead

What is not mentioned in this article , which I find misleading, is that ILS was developed for Cat III auto landings in the 1960's and that it did not come into regular use till the 1980's. from the article http://en.wikipedia.org/wiki/Autoland

".......The provision of the necessary ground equipment (ILS) and associated systems for Category 3 operations was almost non existent and the major manufacturers did not regard it as a basic necessity for new aircraft. In general during the 1970s and 1980s it was available if a customer wanted it, but at such a high price (due to being a reduced production run item) that few airlines could see a cost justification for it.............."

Thats almost 20 years and when you think about it MLS came in 1988 so 20 years later is about now.

What I think is happening is that the cost of upgrading aircraft instruments is expensive and its not till new aircraft are purchased that the new technology is implemented. I think this needs to be added as a footnote. —Preceding unsigned comment added by Tg123 (talk • contribs) 17:00, 4 April 2009 (UTC)

Shouldn't this section of the Wiki entry be updated to show that the use of MLS is to all intent ended & that MLS has no real future? — Preceding unsigned comment added by Oddbodkin (talk • contribs) 22:02, 5 April 2015 (UTC)

Better History Needed

Nowhere is TACAN mentioned. I understand that MLS is a belated civil version of TACAN. DME was developed quite independently from other nav aids, and was the first interrogation system. Locally corrected GPS is generally called "differential". — Preceding unsigned comment added by 220.244.85.38 (talk) 06:48, 4 September 2012 (UTC)

plus-or-minus

There is no reason to write +/- 1200 feet when one can write ±1200 feet. I changed it. Michael Hardy (talk) 03:11, 28 July 2014 (UTC)

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Merger proposal

I propose that Microwave scanning beam landing system be merged into this page. The Space Shuttle system is relatively non-notable, and would be more appropriately described on a sub-section on this page. Balon Greyjoy (talk) 09:40, 8 July 2019 (UTC)

• Support merging per nom. --Soumya-8974 ^talk _contribs ^subpages 14:00, 23 August 2020 (UTC)

  Y Merger complete. Klbrain (talk) 09:08, 19 September 2020 (UTC)