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sidfadc

New NGX user, totally confused about wind integration

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I export my flight plan from simbrief

I import the .PLN file into REX Essentials.

 

Problem is the Winds aloft reported through Simbrief are different to the Winds aloft reported in REX Essentials?

 

My question is which data do I use when setting up the FMC in the NGX?

 

Cheers

Sid

 

 


Thomas Derbyshire

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My question is which data do I use when setting up the FMC in the NGX?

 

Whichever one you want to trust. I'd trust SimBrief over REX Essentials for accuracy to the real world...however...keep in mind that REX Essentials is the one driving the weather in the sim. So, in that case, I'd use the REX values.

 

Also, keep in mind:

-It's best to use the ISA DEV field rather than basic temp. If a temp is entered out of the limits, it can cause issues with the time predictions, and cannot be corrected (we are aware of this bug - the real aircraft simply rejects temps out of limits). ISA DEV temps are harder to mess up, since they're adjusted for altitude.

-The ISA DEV / TEMP it's asking for is the Top of Climb temp (weather programs usually calculate this point for you and can insert this into the weather digest).

-The cruise alt is asking for an average of the wind at cruise (which weather programs also usually provide).


Kyle Rodgers

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Sorry for the late reply.  Apologies forgot to say thanks!

 

No worries. You're welcome!


Kyle Rodgers

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Timely topic (or at least now that it's been brought back). For the cruise winds, is there a smart way to calculate this if you're using Active Sky?

 

I seem to run into two issues, the first of which isn't relevant but worth mentioning during the course of explaining the second...

 

Usually what I do while in "dispatch mode" is open up PFPX (which, of course has an NGX module (I use TOPCAT as well)) and then integrate the weather (from ASN). Both PFPX and ASN give me "average wind components" but no average cruise wind. The first issue is that the average wind component is different between ASN and PFPX which doesn't make any sense since PFPX again uses ASN for weather inputs. But anyway...

 

The second is that I'm left on my own to calculate cruise wind which I do pretty sloppily: I look at all of the cruise waypoints in the flightplan in ASN and sorta just average things in my head. PFPX makes the descent forecast much easier. This is what I usually get in the OFP:

 

WIND INFORMATION - OBS ASKY
--------------------------------------------------------------------------------
(CLIMB)                     MQP                          PNH                          KENTO             
FL370  257/082 -54  FL420  257/102 -59  FL420  251/102 -58  FL420  250/104 -57
FL300  257/067 -37  FL400  257/102 -59  FL400  251/102 -58  FL400  250/104 -57
FL220  251/041 -18  FL380  257/101 -57  FL380  251/100 -56  FL380  250/104 -56
15000  242/025  -5  FL360  257/098 -53  FL360  251/098 -53  FL360  250/105 -54
 7000  207/025 +12  FL340  256/095 -49  FL340  251/096 -49  FL340  249/106 -52

PUB                           (DESCENT)         
FL420  251/104 -57  FL370  245/102 -54  
FL400  251/104 -57  FL300  243/107 -44  
FL380  251/105 -56  FL220  243/076 -27  
FL360  251/108 -54  15000  245/040 -14  
FL340  250/110 -52   7000  206/001  +1

 

(This was a flight from KIAH to KEGE that I did recently, set on March 1, 2015's weather). PFPX tells me that the average wind component (presumably of the entire trip) is HD048 KT.

 

So to the OP, if you already have (or are considering buying) PFPX, the descent forecast is made easy. Cruise wind, not so much. The data uplink in the 777 is much more convenient...


Greg Montey

 

"Because with great power, comes great responsitriligence..."

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For the cruise winds, is there a smart way to calculate this if you're using Active Sky?

 

If I remember correctly, there's a section in the ASN digest of the flight plan that shows the overall average. Just scroll to the bottom of the flight plan window.


Kyle Rodgers

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At the very top of the briefing page there is indeed a line for "Average winds (temps): 253/60 (-30.53)" (also from the same flight plan). Again, I take this to mean that this is from the whole flight, including climb and descent whereas the NGX wants cruise winds. Certainly understanding how averages work, I don't think we can confidently use that figure unless the flight was over a certain length so that the winds during climb and descent are averaged out (unless the winds during either/or are really high or really low compared to those at cruise).

 

Is it safe to assume this is another "only-in-the-sim" problem? E.g., RW dispatch handily derives the correct cruise wind data for the flight crew?

 

Thanks again and sorry for being, er, long-winded...


Greg Montey

 

"Because with great power, comes great responsitriligence..."

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The first issue is that the average wind component is different between ASN and PFPX which doesn't make any sense since PFPX again uses ASN for weather inputs. But anyway...

I think ASN uses a simple average that does not take into consideration the distance between waypoints and the distance that plane might be exposed to a certain wind direction/speed and PFPX is a weighted average that accounts for distance between waypoints. At least that what I was told by the developers of both ASN and PFPX.


Michael Cubine
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At the very top of the briefing page there is indeed a line for "Average winds (temps): 253/60 (-30.53)" (also from the same flight plan). Again, I take this to mean that this is from the whole flight, including climb and descent whereas the NGX wants cruise winds. Certainly understanding how averages work, I don't think we can confidently use that figure unless the flight was over a certain length so that the winds during climb and descent are averaged out (unless the winds during either/or are really high or really low compared to those at cruise).

 

Is it safe to assume this is another "only-in-the-sim" problem? E.g., RW dispatch handily derives the correct cruise wind data for the flight crew?

 

Thanks again and sorry for being, er, long-winded...

 

That's a question for HiFi, honestly, but the climb and descent segments are so short, compared to the rest of the flight (and if they aren't, the cruise average doesn't matter much anyway, then, does it?) that any skew is likely negligible.

 

So, here, the "only in the sim" problem is twofold:

  1. Real world dispatch programs pull from real world sources in a way that is likely more accurate.

    (Though do keep in mind that the wind data on the ADDS site is listed on the forecasts page, and not any observed/actual data - accuracy concerns.)

  2. Simmers tend to hyperfocus on relatively inconsequential things. Sure, bad data can get you bad predictions, but no data is ever going to be perfect, particularly when it comes to wind. This is the entire reason for the tons of extra pages in the dispatch paperwork - Planned versus Actual. Wouldn't be a need for all of that if we were able to get perfect forecast data. That being said, get close and remember you have CONT fuel for a reason.

Kyle Rodgers

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Just to clarify, you are loading your flight plan in to ASN arnt you? Since from memory that gives average cruise wind


Chris Smith

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Just to clarify, you are loading your flight plan in to ASN arnt you? Since from memory that gives average cruise wind

 

Yes of course. But again, ASN just gives you average headwind component for the whole trip.

 

And thanks Kyle. I guess the short version of all of this is just "fly the damn aircraft" and not worry about a couple of forecasted wind knots...

 

And flying around with cont fuel takes the fun out of everything.


Greg Montey

 

"Because with great power, comes great responsitriligence..."

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And thanks Kyle. I guess the short version of all of this is just "fly the damn aircraft" and not worry about a couple of forecasted wind knots...

 

 

 

And flying around with cont fuel takes the fun out of everything.

Heading toward the west and southwest out of KJFK during the winter is more than a couple of forecasted wind knots. You are going to need your reserves then.

Michael Cubine
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I've recently ditched Rex essentials and bought Active Sky next because of various issues I had which I couldn't resolve.  One of the best purchases I have ever made!  I think I'm pretty happy with how I interpret the winds aloft through ASN and implement them into the FMC so I'm a happy bunny.  I find the reported winds through simbrief are pretty much accurate to ASN.  I still use the ASN winds though because its what's driving the sim.


Thomas Derbyshire

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