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# Average route winds

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I think I had a problem with average route winds in build 163.Could Damian or Jim comment on the attched screen shot please?It looks to me as though the winds are NW to NE yet the average route wind is shown as 166 degrees which seems to be 180 degrees out?BTW thanks for the latest build guys.http://forums.avsim.net/user_files/105414.jpg

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Hi,I came out with 171 by hand.You have 10 SWYou have 4 NWYou have 10 NEYou are looking at the WDIR right?Hope this helps,JimActiveSky Supporthttp://www.hifisim.com/images/as2004proudsupporter.jpg

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Hi Jim,I don't know how does AS calculate the average wind, but if it's calculated taking into account direction AND speed, the correct value for the above flight plan should be 305/77 (that is the computed value if you do a sum that calculates a "weight" for each value multiplying direction x speed, effectively giving you a vectorial sum).If it takes into account only direction, the correct value should be 352 as for direction and still 77 kts as for speed.171 or 166 seem to me both wrong.

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>You are looking at the WDIR right?

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I think it is a problem of the program not knowing where the winds are. The average is the sum of all the numbers divided by the amount of numbers added up (25 I think). Adding up the directions I got 4146 and divided that by 25 to get 165.84 or 166 which is in the average.Now The problem I am talking about is that the program does not realize that the winds are swinging from NW-N-NE as we see in increasing direction values. Extrapolating the teens and twenties numbers with 360 added (there were 11 of them, so add 11x360 to the 4146 added above to get 8106) and divided by 25 I got an average wind component of 324.24, which should be the proper answer.Instead, the program assumes that the winds went from NW-W-SW-S-SE-E-NE hence the average of 166.I guess what I'm trying to point out is that the wind can swing both directions.I guess it another bug that might be able to be fixed by the gurus from hifi!!!DevinCYOW

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It's a simple arithmetic average - add up all the WDIR values and divide by the total number of entries. Works out to to about 165.86, rounded up to 166. The difficulty is that you have a severe wind direction shift mid-way through the route; the values don't "cancel" each other out, rather they "average" out to 166 which won't help much in FMC calculations unless you enter the average for the first series of the generally westerly winds, then update with the average of the generally easterly winds mid-way through the flight.Jerry PostKORF

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Thanks for all the replies and math calculations but I still think there is a problem especially if wind speed is taken into account, less so if speed for each direction is ignored.It is many decades since I had to use vector diagrams so I had to go looking on the net on how to produce them.I started by breaking the reported values down into quadrants and averaging the direction and speed, the results I got were231 degrees at 68.6kts332 degrees at 26kts24 degrees at 90kts.If you do a head-to-tail vector diagram of those values you should end up with a wind direction of 350-020 degrees, not 160 degrees.I cannot be more accurate because I only sketched the vectors, even ignoring the wind speed and making the vectors the same length (same wind speed) you still end up with a Northerly wind not a Southerly one.If anyone needs help with vector diagrams, as I did, try this link.http://www.glenbrook.k12.il.us/gbssci/phys...tors/u3l1b.htmlI don't wish to labour the point and I leave it up to Damian and team if they wish to look at the problem but I will now look more closely at those average winds before entering them in a fuel planner for head or tail wind.Rgds

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Hi All,Thanks to everyone for their ideas! It's good to see everyone's thoughts without bashing and name calling as can happen in other forums. I used the simple math average, but must have punched a number in wrong. There is only one way to know for sure, so I'll point Damian to this thread. Maybe it's a bug or maybe it's a simplestic calculation!Hope this helps,JimActiveSky Supporthttp://www.hifisim.com/images/as2004proudsupporter.jpg

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Hi all :)It's a bug in the calculations... Will get this fixed ASAP! Thanks for all the feedback!Best,

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No All.... I didn't get a chance to point this out!!Hope this helps,JimActiveSky Supporthttp://www.hifisim.com/images/as2004proudsupporter.jpg

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Jim,>It's good to see everyone's thoughts without bashing and name calling as can happen in other forums.

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Hi Damian,in the fix you plan to implement the vectorial sum ? This will give a much more correct result !Thanks a lot.Enrico.

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Hi Enrico,The fix was a simple correction of the code, the wrong variable was called in the summing of the "itemized" directions. If workdirection > 180 then workdirection = workdirection - 360. Unfortunately before it was if workdirection > 180 then = - 360. Thus it was never properly making the >180 values negative and thus the incorrect calculation when the wind swings around the 0deg mark.All fixed! B173 available at top of forum!Thanks again all!

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Many thanks for the fix Damian for what was probably an obscure bug.

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You're very welcome - And many thanks for helping us isolate it!!!

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Hi, I'm using Build 174 and I think there may still be a problem with the average route winds calculation. See below for a flight plan from VHHH to WSSS. The winds seem to be mostly from the W, then S and then SE. And yet, the average route winds are 328/40 - the NW. Seems a bit strange.Thanks,EdwinVHHHPORPA 7.1 79 77 265 85 -39.5 450 534 1Fix01 2.4 128 135 265 85 -39.5 450 510 1BREAM 31.9 181 191 265 85 -39.5 450 436 4PERCH 17.8 206 215 265 85 -39.5 450 402 2SANDI 67.4 190 200 265 85 -39.5 450 423 9EPDOS 84.4 188 198 265 85 -39.5 450 425 11ENBOK 26.8 188 196 266 71 -39.9 450 431 3EPKAL 51.8 217 223 266 71 -39.9 450 401 7EGEMU 64.2 218 224 266 71 -39.9 450 400 9EXOTO 121.3 216 223 266 71 -39.9 450 401 18VEPAM 103.2 216 218 281 19 -41.3 450 441 14KARAN 93.0 212 214 281 19 -41.3 450 442 12PTH 121.2 211 212 277 15 -41.2 450 443 16ELSAS 56.5 213 214 269 11 -41.1 450 443 7CS 100.2 212 213 269 11 -41.1 450 443 13ESPOB 121.8 211 212 269 11 -41.1 450 444 16ENREP 149.5 211 210 192 8 -41.1 450 442 20VEPLI 60.6 188 187 136 7 -41.3 450 445 8EGOLO 33.1 188 187 136 7 -41.3 450 445 4VMR 56.9 188 187 136 7 -41.3 450 445 7VJR 42.2 200 198 113 12 -41.4 450 449 5JB 14.8 158 156 113 12 -41.4 450 441 2SJ 18.7 152 151 113 12 -41.4 450 440 2FF02L 4.4 85 86 118 16 -41.5 450 436 1WSSS 7.8 22 24 118 16 -41.5 450 451 1 ----- ----- 1458.9 193m 3.22HAverage Route Winds for 37000ft: 328/40

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Nobody has any ideas? Or perhaps it's because the table isn't aligned so it's hard to see what I'm talking about? I'll try to make things easier below:(Format: Waypoint - WDIR WSPD)PORPA - 265 85Fix01 - 265 85BREAM - 265 85PERCH - 265 85SANDI - 265 85EPDOS - 265 85ENBOK - 266 71EPKAL - 266 71EGEMU - 266 71EXOTO - 266 71VEPAM - 281 19KARAN - 281 19PTH - 277 15ELSAS - 269 11CS - 269 11ESPOB - 269 11ENREP - 192 8VEPLI - 136 7EGOLO - 136 7VMR - 136 7VJR - 113 12JB - 113 12SJ - 113 12FF02L - 118 16WSSS - 118 16Any ideas would be much appreciated.Many thanks in advance.Edwin

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Edwin,If you reduce those winds to 2 components you get an approximation of 269@55 and 130@11The SE winds are 1/5 the strength of the Westerly winds so I would expect something in the region of 240 degrees not 328You can do a vector diagram using rule and protractor to get a closer approximation.See my earlier post on average winds for a link to a web site on how to construct vector diagrams.HTH

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Thanks Vulcan. That confirms my suspicion.Jim, could you please get Damian to look again at the calculation?Thanks again.Edwin

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Hi,Will do. Keep in mind that he has some real-world stuff happening in the next few days.Hope this helps,JimActiveSky Supporthttp://www.hifisim.com/images/as2004proudsupporter.jpg

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Hi all,Well we had quite a few success reports in B174 for average route winds, but it is apparent the calculations aren't sophisticated enough to handle all situations. Indeed, the wind speed is not correctly considered in determining the displayed average, and this is throwing things off especially when you have large variations in speed.We will re-design this but it may take a little time, as we are currently deep into final coding of the next major version upgrade, and as Jim mentioned, I have some other personal priorities that will keep me busy over the next couple days.Vulcan and those who have been testing this, please send me an e-mail in about a week, I will send you a build with the re-designed calculation and we can test it a good deal before providing an official update. Your help is much appreciated!Thanks all..

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