Talk:Approach lighting system

Category on Commons
Hi, just wanted to inform that (a small category) commons:Category:Approach Lighting Systems has been created on Commons in case any of the images there could be of relevance in this article of useful to link to. -- Slaunger (talk) 21:35, 8 March 2008 (UTC)

SALS
Just a short hint: In the en-article SALS means Simple Approach Lighting System; in de-wiki it means Short Approach Lighting System!? Greetings Redlinux ···→ 12:53, 8 August 2011 (UTC)

Decision Bar
The article describes what a Decision bar is for, but does not describe how to identify it. I did all my IFR work at small airports, so did not often have the pleasure of a rabbit, let alone such a luxury. Is that a decision bar visible in the photo? —EncMstr (talk) 21:48, 3 February 2012 (UTC)

"Altitude beacon"
Since Swedish in my native language, some special term are difficult to find out. I don't even know their name in Swedish either. I simply couldn't find the term for it. "Altitude beacon" clearly was wrong. OK. However the lights exists and works similar to common sector lighthoses, but the sectors are vertical instead. I actually wrote further down, that they do not meassure altitude at all, only the aircrafts vertical position compared to the optimal glidepath. I simply stated they exist and how they are to be interpreded. Article was about all other lights surrounding the runway, so I think You could have changed the title instead. Or do You say there was any errors in the text, except the headline ? In general many aviation articles gives lots of space for ground facilities, but far too little regarding how it works from the pilots' point of view. Boeing720 (talk) 03:08, 2 June 2015 (UTC)


 * This article begins saying "An approach lighting system, or ALS, is a lighting system installed on the approach end of an airport runway and consisting of a series of lightbars, strobe lights, or a combination of the two that extends outward from the runway end." It also mentions reduced visibility in the lead as well. This article is not meant to discuss all forms of lighting surrounding a runway, just the ones on the approach, before you get to the actual runway. What you described is a VASI or PAPI system used to confirm that an aircraft is on the glidepath. Those sit roughly 1000 ft beyond or after the approach threshold, and have a different function than an ALS. We should not try to explain a separate topic in an article that is talking about an ALS. In the United States, they are usually set at around 3 degrees and must match the electronic (radio navigation) glide slope, if the runway has one. In my area of the world, nearly every airport has some sort of VASI/PAPI type system for visual guidance, even small general aviation airports seem to have them. Only the larger airports with precision navigational approaches seem to have an ALS. I did not try to rework the paragraph you mentioned because I could not see that the material was meant to be covered in this article. There are two article already discussing VASI and PAPI. Also, I don't think that VASI/PAPI are designed for poor visibility situations, but an ALS is generally required to exist for precision landings. You could check with WP:Aviation and ask someone for a second opinion if you'd like. --Dual Freq (talk) 21:14, 2 June 2015 (UTC)


 * They are intended to match the glidepath, and can most certainly be of aid for the pilots several nautical miles away from the runway in question. But of couce they are not of any help in fog or short visual sight. Neither are they the primary tool for following the glidepath during manual approaches. And as I wrote, at some regional airports in the US a different but similar system whith two pair of lights/beacons rather than one row with four, exists. I can't possibly know for certain, but I think those isn't used outside North America. But the Precision approach path indicator (I hadn't got a clue what they were called, so thanks) are to my knowlidge always located on the left side of the runway. Which isn't the case in the picture to that article. I might be wrong, but I have never seen them to the right.


 * But when the pilot in command (PIC)watches his/her instruments, the other pilot handles the communication radio, folds down flaps (and slats) and is looking out, mainly for the runway (and later for possible obstacles on the runway). I would say, of the all lights around a runway, the yellow/white border markers are of highest importance, especially in darkness of cource. All other lights are more or less of equal importance one way or another. The Precision approach path indicator is of some use during daytime aswell. If let's say the Pilot in command is new and young, then the more experienced captain usually needs to supervise the approach thoroughly. The lights/beacons can't be used so late as when the aircraft is passing the green line. Just imagine the pilot's eye level in a Boeing 737 compared to the same in a Boeing 747. One engined piston-engined planes may perhaps have use of them also in a late phase of an approach. To my knowlidge a small Cessna can land even before the green line. But the Precision approach path indicators are rare equipment at smaller airports, I guess.
 * How do You feel about a link to PAPI's ? Boeing720 (talk) 23:58, 4 June 2015 (UTC)

I think part of the problem is the language. You are interpreting approach lighting systems as all lighting around a runway that one might use to make an approach to land. However, this article is structured towards the ICAO definition of a specific type of lighting found at an airport called an "Approach Lighting System" or (ALS). See Transport Canada's definitions,here, which looks like a copy of the ICAO standard. They have several drawings, like this one of a MALSR type of ALS. They are just talking about the lights before you get to the runway. There are numerous other types of lighting at an airport, but this article is focused on just the one specific type at the approach end of the runway before the aircraft gets to the runway threshold. As for the links, there are links to PAPI and VASI in the see also section of this article. Those systems fall under the "Visual Approach Slope Indicator Systems" types of lights as explained on Transport Canada's website. Precision approach path indicators are found at nearly every airport in the US that has general aviation traffic, even very small ones with only one runway. In the US it probably depends on which state it is in, but they are all basically at every county level and municipal airport with a paved runway around me. Some may only have two boxes instead of 4. Some may only have two lights in each box while others have 3. Some may still have older VASI type systems with 2 or 4 boxes. It depends on the budget. None of them are technically approach lighting systems, but they seem to be ubiquitous. ICAO calls VASI and PAPI type systems "Visual Approach Slope Indicator Systems" and wikipedia tries to address the various kinds at the Visual approach slope indicator article. --Dual Freq (talk) 00:43, 5 June 2015 (UTC)

File:A_jet_airliner_approaching_Copenhagen_rwy_04R_(and_04L),_the_PAPIs_are_different_due_to_different_distance.jpg
 * Here You can see the PAPI lights of two parallel runways (22L and 22R at Copenhagen Airport), but as You also can see, there right runway is further away from this MD80 or MD81.

(I file name became wrong, sorry). At which runway is landing intended ? The localiser clearly shows the right one - "runway to the right" if You look below the artificial horizon. Or runway 22R (220 degrees) in this case. You can clearly see four white lights to the left of the left runway (22L), but there is two white and two red for 22R. So "only" the lateral position isn't correct here. And in my mind not (yet) a reason for a turn around. I think this shows that the PAPI lights is a part of a runways Approach lightning system, somehow. Please notice there remains 4 to 5 nautical miles to 22R, and in good conditios can these lights be seen even further away. I couldn't make the file larger, this picture is NOT Public Domain, but for discussion only. Boeing720 (talk) 01:40, 5 June 2015 (UTC)

Sorry, when I was attempting to upload the picture, I didn't notice Your reply. I've now studied Your interesting links. But it's close to 4 o'clock in the morning here and sunrise is around 4:45 (at LAT 55.85 LONG 12.9 approx). I will have a more thorough look tomorrow. Cheers Boeing720 (talk) 01:57, 5 June 2015 (UTC)


 * I am studing You Canadian runway manuals. But though of this - the radio beacon markers (whatever they are called), those which illuminate as white, orange (or amber) and blue in cockpit are not used at every international or other larger airports. Both the PAPI's and the markers are old technology, are they not ? I'm not at all certain, but it's possible that PAPI's not are mandatory in Canada (and elsewhere). And just like the markers at many airports (especially all three, on all runways) the PAPI's presumably will vanish by time, what do I know. So I thought perhaps the Canadian manual omittes non mandatory equipment ? Nevertheless I still think the PAPI's are a part of Approach lightning system, where they exist. Having stated (all) this, I just want to add that my contribution although wrongly labeled was made as an honnest attempt to improve the article in question. I'm not in this for any kind of glory. And I leave it up to You to decide this matter, but please have a look at the picture. All well Boeing720 (talk) 01:52, 7 June 2015 (UTC)


 * I don't understand the question regarding the flight simulator image, so I didn't reply. I don't want to discuss an flight simulator, I don't even know if that simulator is properly modelling the behavior or locations of the lighting systems. The Transport Canada document I linked is (as far as I can tell) a direct copy of the ICAO instructions or guidelines. I think this is a language or grammar issue as I said earlier. A PAPI is not defined by ICAO as an "Approach Lighting System" it is a "Visual Approach Slope Indicator System" they are both separately defined. This article is about systems which the ICAO defines as "Approach Lighting Systems". PAPI's are 1000 ft away from an ALS, they are completely and totally separate and independent systems from one another and perform completely different and separate functions. Many runways have no ALS but they might have a PAPI. There are several systems of lights a pilot might use to land or taxi around an airport, but this particular article is limited in scope to just "ALS" type lighting systems, as defined by ICAO and linked above. --Dual Freq (talk) 02:23, 7 June 2015 (UTC)


 * PAPI systems are not really that old, they are, as far as I can tell, one of the newer forms of "Visual Approach Slope Indicator Systems" replacing an older system which is known as VASI. This is a bit confusing because VASI also stands for Visual Approach Slope Indicator, but a PAPI system and a VASI system are both considered "Visual Approach Slope Indicator Systems" by ICAO. They perform identical functions, providing a visual representation of a 3 degree (or whatever they are commissioned to be at that runway). I think PAPI is 1990s tech vs VASI 1970s tech, but don't quote me on that. Lights don't get much more complicated, someone probably makes an LED lamp version, but not much can be improved on there. --Dual Freq (talk) 02:23, 7 June 2015 (UTC)


 * As for ILS Marker beacons, those are not even lights, they are 75 MHz radio frequency signals a receiver in the aircraft picks up then converts to a flashing light. They are certainly not approach lighting systems. Marker beacons are not needed if the ILS has a DME system or some other way to determine distance. --Dual Freq (talk) 02:23, 7 June 2015 (UTC)


 * But please - I just stated the Marker beacons as not used at all airports as they no longer are needed. So regarding Your Canadian runway guide, it just crossed my mind that PAPI's perhaps also isn't mandatory and hence not mentioned in that PDF. OK ?
 * The point with the photo is (although wrongly named - correct is 22L and 22R not 04L and 04R) that the aircraft is notably closer to the left runway - due to the fact that dispite being parallel, the left one 22L shows four white lights - meaning far too high. But the right runway 22R shows 2 white and two red lights - or good enough glidepath (the fact that the aircraft is located a bit too left isn't the question here).

You wrote something about the importance of the PAPI's location, 300 meters behind the green line (or the "line up- line"). But here You can clearly see that the PAPIs is used 4.5 nautical miles away from the right runway. You can COMPARE with the around 1.2 nmi closer beginning of the right runway. I wanted to show You that the PAPI's infact are the second most usable visual aid for pilots (after the yellow border markers at night), and during daytime the PAPI's are the only ones that are on (in sunshine).
 * About the gauges - the glideslope is located on the left side in the artificial horizon, a small white arrow (but larger than the indicators on the vertical scale), while the localiser below the horizon (but still inside the horizon gauge), there is a equally while bar (higher than the horizontal scale) this is not in middle position, just as the aircraft is located to the left (the ILS instruments shows the DIRECTION to steer in order to find the central position, here the localiser bar is WHITE, its top enters the brown area of the horizon - almost as far to the right as possible. Hence the navigation radio frequency [see the AT/AP panel] is set to 110.90 MHz - exactly correct for Runway 22R at Copenhagen-Kastrup EKCH/CPH, and on the gyro-compass You can see the heading is close to 230 degrees and after a 10 degree adjustment to the right, the aircraft is on 220 degrees [presumably the pilot needs to adjust the heading more than once though, but 220 degrees is set]. IF Runway intended was 22L (the left on the image), the localiser bar would indicate a small LEFT turn instead.  (Never mind the Flight Director, the yellow "cross" and the fast/slow indicator on the left of the horizon)

THE REMAINING DISTANCE is also related to the preset runway, 22R - and of this final leg of the flight remains between 5 and 6 nautical miles, see the GYRO COMPASS top left corner. Never mind the 340 deagrees for heading, in Autopilots HeaDinG, HDG is the direction the aircraft is pointing at, while NAVigation is the direction which the aircraft is moving towards. With strong side winds (greatest difference appeares when crossing a Jet stream at 35000+ feet, then the wings begins to "act" like a bird - while flying in the Jet stream, headwind or tailwind is far from that nasty) HDG and NAV might become very different things.


 * So the supervising pilot has indeed use of the PAPI, and can (if PIC) doesn't change directon

point that out instead. I don't buy that 300 meter talk. And I can't help thinking that the PAPI's are as much visual aid one can get during an approach. All beacons in front of the runways have only one purpose, and that is to visually help the PIC and supervisor to immidiatly get all possible confusion out of the brain - if the cloud ceiling is low - and even more so if the aircraft comes out of the clouds during a sharp turn.
 * I can't really see why You don't want the PAPI's mentioned among VISUAL approach help. But OK I leave it to You to decide. I just wanted to be of help. Cheers Boeing720 (talk) 10:22, 7 June 2015 (UTC)

PAPI is mentioned in the ICAO PDF document, but not in the ALS section because it is not an ALS. They explain where and when to use install a PAPI in the "Visual Approach Slope Indicator Systems" section, 5.3.6. Yes, a PAPI system is used when making an approach to land at an airport, but it is totally separate from the "approach lighting system" and is not needed / required by ICAO in the same situations as an ALS (which is mainly for poor weather). There are many other lights a pilot uses to make an approach to land, but this article is intended to discuss only one specific system, the "Approach lighting system". PAPI is linked in the see also section. I appreciate you uploading an image of your flight simulator, but I know what a PAPI is, so you need not explain to me what it is for. --Dual Freq (talk) 12:50, 7 June 2015 (UTC)