B744 FMC forcast wind input?
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B744 FMC forcast wind input?
Hellow ,I am working on my transition to 744 and find on this longhaul airplane as weight decreases, we may cover many flight level ,but The FMC only allows you to input forcast wind for four flight level,so what is the best way to set this? thanks! 
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If ACARS is available, upload the levels to be used first before T/O. After climbing from a lower level, delete that level, add a higher one, and update.
When at the highest/final cruising level, update again with lower-altitude winds for the descent. If cruising at FL350 or above, upload 090, 180, and 240.
When at the highest/final cruising level, update again with lower-altitude winds for the descent. If cruising at FL350 or above, upload 090, 180, and 240.
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Just enter the winds/temps at one level.
In my company on the 744 we can't upload forecast winds into the FMC. We enter them manually from the flight plan. The last few pages of which has forecast winds and temps at 4 different levels including the planned level for each stage.
Manually entering four different winds for every waypoint would take hours. So we enter one level, the initial cruise level, and then enter the forecast winds along the route all entered at this intial level. You will enter the winds/temp of the level you plan on being at.
You then enter step climbs ( eg. /FL360S ) into the LEGS page where you plan/expect to climb and the FMC then sees what levels you will be at all the way to destination. (This is done so the Mach No./TAS & fuel flow are accurately predicted).
So when it looks hours ahead at some higher level you've told it you'll be at the FMC is forced to "look down" at the only available wind you've entered (which was the forecast for that higher level).
This works very well and saves you manually entering multiple levels of winds.
Forecast descent winds are entered on VNAV Page 3 FORECAST at FL350, 310, 200 and 10,000' (again from the flightplan)
Sorry for the long answer, I hope it makes some sence...
In my company on the 744 we can't upload forecast winds into the FMC. We enter them manually from the flight plan. The last few pages of which has forecast winds and temps at 4 different levels including the planned level for each stage.
Manually entering four different winds for every waypoint would take hours. So we enter one level, the initial cruise level, and then enter the forecast winds along the route all entered at this intial level. You will enter the winds/temp of the level you plan on being at.
You then enter step climbs ( eg. /FL360S ) into the LEGS page where you plan/expect to climb and the FMC then sees what levels you will be at all the way to destination. (This is done so the Mach No./TAS & fuel flow are accurately predicted).
So when it looks hours ahead at some higher level you've told it you'll be at the FMC is forced to "look down" at the only available wind you've entered (which was the forecast for that higher level).
This works very well and saves you manually entering multiple levels of winds.
Forecast descent winds are entered on VNAV Page 3 FORECAST at FL350, 310, 200 and 10,000' (again from the flightplan)
Sorry for the long answer, I hope it makes some sence...
Last edited by Harry G; 12th Jan 2005 at 18:07.
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Manually entering four different winds for every waypoint would take hours. So we enter one level, the initial cruise level, and then enter the forecast winds along the route all entered at this intial level. You will enter the winds/temp of the level you plan on being at.
Our Navtech flight plans have that info on the route pages as well as the overall planning table at the end. If you don't have winds at the correct altitude at each waypoint, interpolate from available data.
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There is no requirement to be inputting winds for every waypoint! Rather prior to departure input a TOC wind to give the FMC something to work with. Otherwise, too much time would be spend inputting data that is not required immediately. On climb out, and initial cruise, you can anticipate an "INSUFFICENT FUEL" message if strong tail winds are catered for in the flight plan. Once level, you can input relavent winds. Different companies will have varied SOP's on this, but every hour is not unreasonable, and whenever there is a signifant change in the magnitude, or direction of the wind. On a 14 hour flight, this is only 14-16 data entries. As for only 4 levels. The FMC, although not the world's best processor, will interpolate between the levels, so again something reasonable. Same with the descent winds.
Word to the wise. Always check the FMC TOD point with what you think is reasonable. Not the oldest trick in the book, but close. You get up for a pee a few minutes prior to TOD. While up, the descent winds are all changes to 200 kt headwinds. If you don't check, you'll only do it once...
Word to the wise. Always check the FMC TOD point with what you think is reasonable. Not the oldest trick in the book, but close. You get up for a pee a few minutes prior to TOD. While up, the descent winds are all changes to 200 kt headwinds. If you don't check, you'll only do it once...
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There is no requirement to be inputting winds for every waypoint!
If we are pressed for time before T/O, we input the average trip wind in the first waypoint after TOC. Then we input the forecast winds when we're settled in cruise.
