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Guest Stamatis

How does runway selection work now with the MS ATC ?

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Up until AFCAD was made available to us, I believe the MS ATC engine worked as follows, when it came to choosing the active runway:1. ATC always chooses the longest runway. (If there are equal length runways I am not sure if it chooses the first in the dropdown list or what)2. If the tailwind is 6kts or greater (could be 10 kts, I am not 100% sure), ATC chooses the most appropriate end of that longest runway.3. If the prevailing tailwind is less than above, ATC chooses the end equipped with an ILS.4. If there is no tailwind and both runway ends are equipped with an ILS, or neither end does, ATC chooses the first in the dropdown list.(Presumably the one with the lower number, but I'm not sure about that)But now that we can selectively "close" runway ends for either takeoffs and/or departures, I am no longer sure how this "active runway selection" process works. Can someone enlighten me please, by stating how the "rules" apply now?Even better, let me use EHAM as an example, and let us assume the following AFCAD configuration:I am listing the EHAM runway configurations in order of runway length ("runway length" being what is entered in the AFCAD file).Please do not compare them to real world, this is not of interest for the issue at hand:06/24 11483ft06: ILS, Landings only24: no ILS, Takeoffs only09/27 11329ft09: no ILS, Takeoffs only27: ILS, Landings only01R/19L 11155ft01R: ILS, Landings only19L: no ILS, Takeoffs only01L/19R 10827ft01L: ILS, Takeoffs only19R: ILS, Landings only04/22 6608ft04: no ILS Takeoffs & Landings22: ILS, Takeoffs & LandingsCan someone explain to me how would this system work, assuming the following surface wind direction situations (let us assume a surface wind speed of 15 kts for all scenaria):Wind blowing from:a) 360 deg:( 045 degc) 090 degd) 180 dege) 225 degf) 270 degg) 315 degStamatis

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Imo,such a cinfiguration is a very bad one: you'll only have one active runway and take-offs and landings:runway 06/24,because this is the longest oneand on that runway will be each on an opposite end of the runwayso you'll always have aircraft taking-off from runway 24 and all aircraft landing on runway06,which si ultra unrealistic of cours.you'll also have aircraft collisions the whole timefor the most realistic runway configuration at EHAM,do a search for my post on this forum

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Seba,Thanks for replying.But I only used this configuration as an example, to understand the logic behind the runway selection process.I have outlined how the logic worked in "default" mode, i.e. before we could modify the AFCAD files.The purpose of my stated example is to understand the logic applied when runway ends are closed by the user, not so much in perfecting EHAM configuration. Can you enlighten me on this please?In the meantine I will certainly search the Forum for your EHAM suggestion :-)Stamatis

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ok,I think it works as follows:the longest runway that is not closed for TO will be used for TO's.If there is more than one runway with the same length,first the ones with ILS will be selected.if they all have ILS,wind direction will determine the runway for TO(if they all have equal length)for landing,just the same thing applies: longest runway not closed for landings will be used and so onif you still have any questions,feel free to ask,I hope I answered your question a bit

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Thank you Sebastian.I also thought about this and basically nothing changes in the logic other than the fact that a different runway can be used for Landings than the one used for Takeoffs. It is as if we now have two sets of calculations instead of one, one for the Takeoffs and a separate calculation for the Landings.But both calculations use the logic and face the same constraints as stated in my first message.The only exception being having multiple runways with equal length.Stamatis

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I believe I've seen situations where VFR and IFR aircraft will select different runways. The VFR aircraft will choose the "appropriate" runway regardless of ILS, but IFR aircraft will go to the ILS runway regardless of wind. This is most noticeable when only one end of a runway is ILS, but the wind is coming from that direction.

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"...but IFR aircraft will go to the ILS runway regardless of wind. This is most noticeable when only one end of a runway is ILS, but the wind is coming from that direction."Yes, it takes a considerable tailwind component, not just any surface wind speed, to switch from the ILS equipped runway end to a non-ILS equipped one. I think the value for the tailwind component must be 6 kts and higher.What interests me is how MS ATC handles equal length runways.What are the rules in such a situation? Which runway end is picked first, assuming all are ILS equipped?Stamatis

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"What interests me is how MS ATC handles equal length runways.What are the rules in such a situation? Which runway end is picked first, assuming all are ILS equipped?"Like I said in mu earlier reply,in that situation(if they all have ILS and have equal lenth), wind direction will define the runway in use. if they have the same direction (parallel runways),then I believe the runway that's first in the list (AFCAD) will be used

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I missed that part of your previous reply Sebastian, thank you.I guess I now have all the "rules" clearly explained, regarding how MS ATC will pick a runway for Takeoff and Landing.Stamatis

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