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Speedbyrd

HECA - Rwys 5/23 ... ATC reverses assignments

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At Cairo, ATC is assigning the "5" runways 5l/r and the 23's 23 L/R in reverse order accoridng to the wind. I couldn't figure out why I was directed to 23L with the wind at 035 @ 10. I should have been directed in the other direction. I did some testing and find that with the wind set at 230 @ 15, I'm now directed to 5L. With the wind at 050 @ 15, I'm directed to 23 L or R! I have a STAR rwy system set up at Cairo so as to use all runways and never noticed this before. I'm using 5L as my starting point, then doing my STAR configuration up to rwy 16, with 7.5 degrees between each. ATC is either misreading the wind or misreading the runways. Any ideas?Thanks,

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Hello,sigh...FS ATC...:-( This does happen from time to time, I think it's airport specific for instance if 05L/R doesn't have an ILS, then FS ATC will assign 23 L/R no matter what. I know it's really annoying if you plan SID and STARS.I'm sorry not to able to help, but you could use AFCADS which I believe let's you assign runways yourself.That said, there are airports where you do land with tailwinds, Zurich is one of them.Regards

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FS does exactly what it is supposed to do with that Star. By the way, you can crank it all the way up to 7.9 degrees.Now, try starting with 16, then going back to the 5's. That way the parallel runways will be the "determining" runways (the runway listed last in your Afcad editor's runway list is the determining runway).So at least for those two runways, the wind and runway end used will always be correct. Not so for 16/34, but that's a limitation of FS and the trick we use to make non-parallel runways work.FYI, all four ends of the parallel runways have an ILS available.

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>FS does exactly what it is supposed to do with that Star. By>the way, you can crank it all the way up to 7.9 degrees.>>Now, try starting with 16, then going back to the 5's. That>way the parallel runways will be the "determining" runways>(the runway listed last in your Afcad editor's runway list is>the determining runway).>>So at least for those two runways, the wind and runway end>used will always be correct. Not so for 16/34, but that's a>limitation of FS and the trick we use to make non-parallel>runways work.>>FYI, all four ends of the parallel runways have an ILS>available.Hey this is great info. didn't know you could work it backwards. I'm also getting my AI's assigned to ficticious runways and I'm not sure why that's happening as those runways are 10' long and closed at both ends for landing and take off. ..... umm

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>FS does exactly what it is supposed to do with that Star. By>the way, you can crank it all the way up to 7.9 degrees.>>Now, try starting with 16, then going back to the 5's. That>way the parallel runways will be the "determining" runways>(the runway listed last in your Afcad editor's runway list is>the determining runway).>>So at least for those two runways, the wind and runway end>used will always be correct. Not so for 16/34, but that's a>limitation of FS and the trick we use to make non-parallel>runways work.>>FYI, all four ends of the parallel runways have an ILS>available.Let me understand the term 'determing runways" if you have parallels operating with a non-parallel, does this mean then that the parallels (or majority) of runways will be operative as primary along with the non-parallel? I wend through some of my STAR setups and notice on some that the non-parallel runway is often given the priority, though there may be two or more parallels that would qualiffy due to wind conditions. An instance were I had a STAR set up for KMIA, I started from rwy 8 and did my STAR through rwy 12, with 12 being listed last and it seems that this single runway gets much of the traffic, though there are 3 parallel runways as well. Rwy 9 gets very little traffic. Thanks for the info on this.

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Whether or not a runway is the "determining" runway has little to no effect on actual usage of the runway regarding the amount of traffic. With 12 listed last, the only thing you say to the sim is, from 30 degrees to 210 of wind, use 12 and the ends linked to it, the 8's in this case and 9. Then from 210 through 360/0 and back to 30, use 30 and the ends linked to it.If you list one of the parallels last, this changes from 0 to 180 (use the 8's and 9, and 12) and 180 to 0 (use the 26's and 27, and 30).Actual numbers may be different, look at the true heading in your Afcad editor.Now, why does 12/30 get a lot of traffic, because its heading is closer to the heading of arrival traffic than the others. Generally speaking, aircraft get assigned a runway that is in their flightpath or one that is closest to it. If an aircraft is flying say a heading of 140 degrees when it gets assigned its runway, then ATC should direct it to 12 (120) instead of the others (roughly 90), because 140 is closer to 120, than it is to 90. If the other ends are in use, it's slightly different, it'll favor 30. Even though the headings of the others may be closer, 30 is still more in the flightpath than the others.If you look solely at the parallels, traffic from the north will take the northern most runway available and traffic from the south, the southern most runway.If you work this all out, you should be able to tell where most of the traffic is coming from. Likewise, if you know where most of the traffic is coming from at any airport, you can improve your Afcad accordingly.Hope that made sense. Most of this stuff is more difficult to explain than to implement. ;-)

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I'll print this out. I makes perfect sense. I observed KMIA quite a lot and noticed this is quite true. Traffic from the north received assignments to Rwy 12 and 8L (winds were 112 @ 8). Traffic coming from Mexico recieved rwy 9. This runway isn't used too much but Mexico and S. America flights do get assigned there. Your explanation makes perfect sense and I do thank you!

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