KLAX-KJFK Case Study

[downscc 1,327]

Flight planning the QF107 flight with all my data referened to 0000Z 9 Dec, found discrepancy in wind data during Wx Briefing: Winds are stuck at 113 (various speeds) except for a couple of isolated points along the route. The constant wind direction, if an attempt to smooth winds, does not resemble in any manner actual winds (see attch Winds Aloft chart from Aviation Wx).I'm trying to understand how to use ASX, so I looked closer at one of the wind data anomolies where the wind is a constant direction (113) for 12 stations before and 8 stations after (stations being flight plan waypoints defined by the loaded flightplan), but this location has winds at FL390 125 degress different! The briefing page, map page and weather briefing say winds at KATES (near KSUX - Sioux Falls) are at 238/96. When I drill-down into the map I find that fake station XSIO is reporting this weird number, but all the stations around including KSUX report 113/xx (xx-vary velocities from 11-102). Now that you've got my curiosity going, I look at the NOAA FB report valid 0Z for ONL (closest reporting station with radiosonde data) and at FL390 I find 740756, which if I remember my decode correctly that's interpreted as winds at 240/107 -56C.In summary, my ASX weather briefing gives an almost constant wind direction of 113, except for a three locations (out of 34) that give a very big wind shift to 238-270 then back to 113. Meanwhile, actual weather products are indicating that winds should be SW gently shifting to the W at mid-continent (225-270).Looks like to me the three locations have data that better resembles the actual winds than the rest of the 31 locations.I don't understand how to work with this.... tried this briefing setup with/without wind smoothing, with/without virtual stations, etc. But still kept getting winds at 113 for most of the route. This translates from a real world 70-100kt tailwind into a 40-50kt headwind.If SP2 is causing this then I suggest there's still more than minor problems to fix.

[downscc 1,327]

Update.. I refreshed the ASX weather at 0055Z 9Dec, it reported downloading the 0Z weather.The almost constant wind direction of 113 has shifted to 203, with the only exception being several stations reporting a closer to real direction of 238-271. Interesting. It's a lot easier to believe that the jetstream is blowing SSW than it is ESE... don't see that very often.Edit update: I started looking at current METARS and saw a connection between the constant winds at FL390 shifting from 113 to 203. The KLAX METAR had surface winds at 113, which are now reporting 203.Holy Cow.. the surface wind direction at my departure is being used by ASX to determine the winds at FL390 for a 2200 nm trip! What am I doing wrong????

[JSkorna 137]

Hi Dan,The constant wind direction is normal for now. What else do you have questions about?Happy Holidays,Jimhttp://www.hifisim.com/banners/hifi-community-sigbanner.jpghttp://www.hifisim.com/

[downscc 1,327]

Is there anything I can do to setup the "constant" wind such that it is at least within the ballpark of reported weather?Edit: The constant wind just changed from about 300/46 to 039/46 over KDAG just after I reached FL390. That was interesting. I opened the nearest station reporting screen, KDAG, the winds were not as shown in the simulation... they were 300/46. Don't know where the 039/46 came from.Edit: Still near KDAG winds gone from 300 to 039 to 076 back to 032 down to 015 up to 025 to 033 ....all in the span of 50 nm.Final Edit: Stopping simulation 50 SW of KLAS at FL390. Winds are rapidly shifting from 010 to 075 to 145 and back. This isn't much fun.

[DF9AA 0]

?????The constant wind direction is normal for now. What else do you have questions about??????I really don't understand this answer . . .To alter the famous saying :"HiFi YOU have a problem" Karl-Heinz - EDDI/THF " Tempelhof "" The mother of all airports " - Sir Norman Fosterhttp://www.precisionmanuals.com/images/forum/747400.jpg

[JSkorna 137]

Hi,Yes, this is the workaround for violent wind shifts right now, to provide the same wind data. No, it is not the most realistic situation, and we are working everyday to improve things.Happy Holidays,Jimhttp://www.hifisim.com/banners/hifi-community-sigbanner.jpghttp://www.hifisim.com/

[downscc 1,327]

Jim: I can only guess how frustrated you guys are.We are too, even if the winds aloft in the briefing are a constant value (for the most part) the violent shifts are still occurring.When I compare your weather provided for nearest station I find no correlation to what FSX is doing during the violent shifts.Seems like ASX reports one thing and FSX does another. To the simple minded, it looks like your effort to smooth data didn't solve the problem. Again, simple minded, it seems like FSX is reponding to something other than your data (I've got ASX running exclusively - no other activity from FSUIPC, etc.).I'm sure you guys know more about this problem than a casual user like myself, but our frustration is due to not understanding the problem you are trying to solve. Worse yet, as an engineer, I have a natural tendency to want to understand and solve problems.Please keep us posted.

[JSkorna 137]

Hi Dan,Another frustrating thing is that some users are have no problems with the data and the shifts and some, like your self, are still getting violent shifts. Are you running with Virtual Stations on or off? Is weather set to User Defined in FSX?Thanks,Jimhttp://www.hifisim.com/banners/hifi-community-sigbanner.jpghttp://www.hifisim.com/

[downscc 1,327]

I've made several short trips with ASX with no problem (eg KPAE-KSFO, KPAE-KDEN, KATL-KJFK). However, the KLAX-KJKF was my first longer distance trial with ASX and it was a bust. I selected the continental route instead of an ocean crossing to take advantage of the availability of WX stations.I ran the preflight briefing with Virtual Stations three or four times with Virtual Stations on and off, and I have Enhance Route Coverage off. Dynamic Rate of Change is 50%. I found the "constant" winds aloft except as noted in several locations where briefing data winds were significantly different from the "constant" norm.The flight was with Virtual Stations off. The location where I experienced the violent shifts had ASX weather briefing data indicating "constant" norm. I alway use User Defined WX but cannot verify that that was the setting; however, next time I load ASX with FSX and set up a flight it is something I will verify and/or investigate.One difference between the KLAX-KJFK flight and the other flights was that the winds aloft were above 100 kts. The earlier flights had a weaker jet.PS. Wind Smoothing is Enabled

[DF9AA 0]

Perhaps this will frustrate you even more . . .Today I flew Dan's trip from KLAX to KJFK and . . .NO PROBLEMS - no windshifts ( at least just minor which did not endanger the speeds )Wind according forecast ( also just minor differences )in all a good and uneventful trip - just 3 minutes later than calculated, mainly on arrival in JFK.Karl-Heinz - EDDI/THF " Tempelhof "" The mother of all airports " - Sir Norman Fosterhttp://www.precisionmanuals.com/images/forum/747400.jpg

[downscc 1,327]

Karl-Heinz: Winds per forecast?? Wow, envy. Once you get East of the trough over Nevada they are pretty constant 100+ kts out of the SW, correct?What are your settings?

[ega 98]

Jim,I regret to inform that I also got no improvement at all on the wind shift problem with SP2. I guess this problem is difficult to iron out. Just for your information: virtual Stations are off and weather is set to "User Defined" in FSX and I use ASX in a second computer linked to the computer that has FSX. WinXP with SP2.Thank youEdmundo

[Damian Clark 1,038]

Hi,To those experiencing significant wind shifts with SP2,Can you share with us what kind of flying you are doing, in what aircraft, at what altitudes? With some guidance we can try and reproduce and attempt some improvements.Best,

[DF9AA 0]

Hi Dan, Damian, JimI am preparing a complete report for this flight and send it to you via e-mail with excel attachmentKarl-Heinz - EDDI/THF " Tempelhof "" The mother of all airports " - Sir Norman Fosterhttp://www.precisionmanuals.com/images/forum/747400.jpg

[downscc 1,327]

I made another attempt at the KLAX-KJFK flight last night departing KLAX at 2300Z LOOP4 DAG J100 LAS BCE DBL DVV J114 YANKI J114 ONL J94 DBQ J94 PMM J70 LVZ LENDY at FL390 with Wind Smoothing OFF. Flight was perfect, much to my surprise because the route to BCE was in a trough with NNE winds light (~10-14 kts) that swung around to the WSW and by DVV increased to 110 kts. There was light turbulence but the PMDG 744X was very flyable. The wind vector didn't swing as smoothly around from NNE to WSW but the changes were not severe enough to cause altitude changes.When I did the preflight, I noticed the Wind Smoothing didn't provide realistic winds (in the briefing) and I wanted to see what it was going to be like flying through an upper level trough into strong seasonal jet so I turned off Wind Smoothing. Virtual Stations OFF and Enhanced Route Coverage OFF.The same route as a day earlier with Wind Smoothing ON, and I couldn't fly it. I was getting severe wind shifts between DAG and LAS at FL390 that didn't show up in the data for any station. I have verified that User Defined WX in FSX was selected. I don't understand why I can't look at the data to see where the changes in wind are coming from.The ground fog at KJFK was excellent! The LENDY arrival route to Rnw 13 comes in from the West over KTEB and N of JFK, then a cross wind entry to a downwind S of JFK. I could see the airport until on final approach when the ground fog modelling decreased visibility such that the approach lights only were visible inside the FAF. Very nice.