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Post by Tom/CalClassic on Jan 26, 2014 12:52:55 GMT -5
Hi all, I just flew from LAX to Heathrow in a DC-7C checking out some things, and I assumed I would have tailwinds in that direction. Turns out I had headwinds almost the entire trip and had to refuel in Iceland before continuing. I wondered if there was an online resource that would allow me to predict the winds aloft, and found this WAFS site from NOAA. weather.noaa.gov/fax/wafswind.shtmlI used the 18,000 ft charts since that is the altitude I was planning my flight for. Other altitudes are available (previous/next page links at the bottom). The chart I used was the 24 hr Europe and Atlantic chart (c. XI): weather.noaa.gov/pub/fax/PWAE50.TIFwhich seemed closest to the Real World Weather I downloaded in FS. It is a TIFF chart of the US, Canada, the North Atlantic, and Western Europe. Perfect for polar flights like mine. You will see a grid of numbers (temperatures, I suppose, although I have no idea why they are low numbers in the tropics and high numbers at the pole), and little flag poles (staffs) sticking out of them. That is the wind direction - the wind comes *from* the direction of the staff, so if the staff is pointing south and you are flying south you will have a headwind. You want to fly so you reach the staff before you reach the temperature number. Each short tick is 5 knots wind, a long tick 10 knots, and a pennant is 50 knots. Just add them up. From today's chart I can see if want a tailwind on that LAX-EGL flight I would need to stay in the US all the way to the Great Lakes, then over Labrador and east to England. Whether that would be better than flying the Great Circle route further north (shorter, but with headwinds) is something more complicated than I can figure out. But if you want to fly the Great Circle route you can check the charts at all the relevant altitudes and see if any of them are better for your route. If anyone has a favorite/better online method to do the same thing I would be glad to hear it. Hope this helps,
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Post by Tom/CalClassic on Jan 26, 2014 13:02:43 GMT -5
PS. For flights in other regions I would just use the other charts in that list - LAX to Hawaii, for example is in the next chart down, North American and Pacific, c. XII: weather.noaa.gov/pub/fax/PWYE50.TIFThese are not perfect, though. It shows that a flight today from PHNL to LAX will have tailwinds the entire distance, but I show a crosswind or slight headwind. Perhaps someone has done some experiments with other freeware weather generators than the default Real World Weather and has better results?
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Post by Wolfgang on Jan 26, 2014 13:41:21 GMT -5
Hi,
maybe these temperatures are in °C and they didn't show the minus. That means, negative numbers are written without minus and only positive temperatures are indicated and have an plus.
Cheers Wolfgang
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Post by Tom/CalClassic on Jan 26, 2014 15:44:19 GMT -5
Hi,
Yes, it does say that they are written without minus marks. San Diego is listed as 17 which is 62F if positive, which is OK, but if negative it's 2F - not true. But Yucatan is listed as 7 (45F if positive or 19F if negative) which are both colder than the lowest temperatures there. And there is no transition to 0 before reaching the pole, which is 36. They just steadily increase from a low number in the tropics as you get closer to the north pole. Very puzzling.
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Post by dave mcqueen on Jan 26, 2014 17:57:41 GMT -5
San Diego is listed as 17 which is 62F if positive, which is OK, but if negative it's 2F - not true. But Yucatan is listed as 7 (45F if positive or 19F if negative) which are both colder than the lowest temperatures there. I was walking in the woods last month and walked into a wasp nest and got stung several times -- this will likely be no different except I won't feel the physical pain !! Looking at the 18,000 foot chart I downloaded -- PWAE50.tif at San Diego 17 degrees is minus 17 Celsius or 1.4 F .......... This makes perfect sense because the chart is for 18,000 feet, not sea level. Same for Yucatan. Intuitively it makes sense that as you go further north the numbers, although they appear to be increasing due to the absence of the minus sign on the map, represent even colder temperatures as you head toward the North Pole. They will vary somewhat with the effect of weather fronts, etc What am I missing?
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Post by Wolfgang on Jan 26, 2014 19:06:01 GMT -5
Hi,
that's what I thought Dave.
Cheers Wolfgang
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Post by Tom/CalClassic on Jan 26, 2014 21:58:00 GMT -5
Oops, forgot about the altitude! You are right, of course, stupid me.
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Post by mrcapitalism on Jan 27, 2014 0:48:22 GMT -5
The chart legend says "Wind speed in knots. Temps unsigned unless positive." Which I interpret as being assumed negative. Which would make sense, lower negative numbers in higher latitudes. Standard temperature lapse rate is -2C/1000'
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Post by dave mcqueen on Jan 27, 2014 1:24:20 GMT -5
Oops, forgot about the altitude! You are right, of course, stupid me. Egad, I just embarrassed the Administrator. Please forgive me .... At Oakland ARTCC they used to shut down the 9020 computer on the Mid Watch and in so doing all upper wind info was lost. When the computer came back up the assistants had to retype all the upper wind data back into the computer from TTY printouts manually before activating active flight plans else the computer would tun estimated positions for any given flight at its filed true airspeed without taking into account the effect of wind. The times could be way off such that if they were relied upon loss of separation or even a mid air collision could result if a clearance was issued that took the estimates to be accurate. Controllers would usually use their own estimates instead of what the computer printed out since they had been monitoring their sectors for hours and knew how long it took to traverse 10 degrees irrespective of what the flight progress strip said. Today the winds are automatically re-calculated and entered and besides they don't shut the computer off anymore, I think
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Post by Tom/CalClassic on Jan 27, 2014 10:45:42 GMT -5
No problem, I do stupid things too, just like everyone else. Yes, if you look at the 5,000 ft charts you can see they place a + next to positive temperatures. Why did they need to turn off the computers? I can understand rebooting once a week or so, but every night?
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Post by dave mcqueen on Jan 27, 2014 14:34:03 GMT -5
They were still turning off the main computer at night in the last year I worked. In the 70s and 80s the reason they gave was that a lot of trash was stored on the hard drives -- which were low capacity compared to what we have today ---that ultimately would slow down or crash the computer if it wasn't cleared out and they had to take the computer off line to do that. Typically from midnight to 6 AM every night. In the 90s and 2000s we had a system called DARC that came on when the computer was offline. It was a simplified version of the regular machine but it lacked flight plan processing capability and other functions. Flight data had to be handwritten and passed physically or via interphone. The reason given for turning it off was that "testing" needed to be done. Also patches and program updates were installed during the computer shut downs. It was a real pain considering the time of day, but the traffic volume was low and that is why they picked that time of day to do it.
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Post by Stratocruiser on Jan 28, 2014 7:26:34 GMT -5
Tom, You say you used Real Weather that you downloaded from FS. You do know that that Real Weather from FS9 and FSX no longer works? The wx you get using that option could be anything from the past, but not what is actually happening at that time. When MS decided to pull the plug on all FS products, they canceled the contract with the provider of the wx downloads for that option.i have been using Active Sky products for several years now and have been very happy with the product. I recently upgraded to the latest version, Active Sky Next, and it is the best wx program ever. If you want a free program try RealWxLite which you can find at Avsim and Flightsim. At Dc3airways.com we use Rea wxLite for our multyplayer flights so that everyone sees the same thing and it works pretty well. We have coated it with Active Sky in real time and it seems to be very close to AS. Anyhow, I don't think you can rely on the Real Weather option in FS for any accurate wx. Howard
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Post by Tom/CalClassic on Jan 28, 2014 10:51:47 GMT -5
Hi Howard,
I have seen some information to that effect, but nothing official. The weather still seems to change, and generally to be what is present in real life (raining, overcast, sunny, etc.). I will try RealWxLite and see if winds aloft are any more accurate.
Thanks,
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Post by Stratocruiser on Jan 28, 2014 16:51:37 GMT -5
Tom, The file name i: fsrealwx_lite_setup.zip The author is Silvio Lafere I got it from AVSIM, but their site has been down all day. You might see if it is also on FLIGHTSIM. Howard
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Post by Tom/CalClassic on Jan 28, 2014 17:35:02 GMT -5
Hi,
I checked and it's not at flightsim, but I got it this morning from AVSIM (they're back up). I'll check it out when I get a chance.
Thanks,
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