ASN and PFPX Winds Aloft

[hopskip 253]

 

Try this. Before loading a route into ASN, go to PMDG/WX and see if there is a WX file pertaining to the route. There is not. Load the route into ASN and immediately go back to the PMDG/WX folder. The WX file for that route is in the folder. I just tried this with the MD-11. It's useless but it's there.

 

Try this:

Create a flightplan in PFPX (example OMDB to YMML)

Click "Release flight plan"

Click "Export"

Check all of the checkmarks, then click ok to export in all formats. (yes, even MadDog MD80 etc, leave none blank). Take note of the saved file name (probably OMDBYMML01)

 

Now open the PMDG 777

Go to RTE page in the FMC CDU

enter (by typing) OMDBYMML01 onto the scratch pad, and then lineselect "co-route"

(the entire flightplan is now inserted except SID/STAR and departure/arrival runways)

 

Now go to LEGS page and click RTE DATA

Line select (bottom right) wind data REQUEST.

 

All the waypoints in the Legs/RTE data page now have a little "W" next to them, and the predicted arrival fuel has just changed (possibly significantly).

 

I haven't even started ActiveSky Next yet. Active Sky Next is not running, has not been running at any point between PC bootup and now, etc.

 

PFPX has imported the weather data.

 

 

... so I'm guessing that if I now bootup Activesky next and import the flight plan (path of waypoints) into ActiveSky next, and tell it I am going to be at FL370 for the whole flight (I'm not, but it only lets you enter 1 entry) that it will then 'overwrite' the file that was put there by PFPX? (which doesn't matter because I'v already run the wind data Request in the FMC?)

[pcubine 143]

... so I'm guessing that if I now bootup Activesky next and import the flight plan (path of waypoints) into ActiveSky next, and tell it I am going to be at FL370 for the whole flight (I'm not, but it only lets you enter 1 entry) that it will then 'overwrite' the file that was put there by PFPX? (which doesn't matter because I'v already run the wind data Request in the FMC?)

 

That sound good. ASN will overwrite PFPX but it makes no difference since the wind data from PFPX is already in the FMC.

[sosuflyer 30]

Try this:

Create a flightplan in PFPX (example OMDB to YMML)

Click "Release flight plan"

Click "Export"

Check all of the checkmarks, then click ok to export in all formats. (yes, even MadDog MD80 etc, leave none blank). Take note of the saved file name (probably OMDBYMML01)

 

Now open the PMDG 777

Go to RTE page in the FMC CDU

enter (by typing) OMDBYMML01 onto the scratch pad, and then lineselect "co-route"

(the entire flightplan is now inserted except SID/STAR and departure/arrival runways)

 

Now go to LEGS page and click RTE DATA

Line select (bottom right) wind data REQUEST.

 

All the waypoints in the Legs/RTE data page now have a little "W" next to them, and the predicted arrival fuel has just changed (possibly significantly).

 

I haven't even started ActiveSky Next yet. Active Sky Next is not running, has not been running at any point between PC bootup and now, etc.

 

PFPX has imported the weather data.

 

 

... so I'm guessing that if I now bootup Activesky next and import the flight plan (path of waypoints) into ActiveSky next, and tell it I am going to be at FL370 for the whole flight (I'm not, but it only lets you enter 1 entry) that it will then 'overwrite' the file that was put there by PFPX? (which doesn't matter because I'v already run the wind data Request in the FMC?)

Bingo. That's what I have noticed as well.

Only difference is I do have ASN running while using pfpx so it can use it's weather generation, but I don't load the flight plan into ASN until I've imported winds generated by pfpx.

[scandinavian13 5,192]

 

 

Are you talking about a bug in the FMC or the folder PMDG/WX?

 

Currently, when the PMDG 777 uploads the wind from the file, it does not release it so that it can be updated.

 

This has been changed in the SP1 version so that the file can be updated over the course of the flight.  Because forecast variability increases with time ahead of current time, wind updates are necessary for more accurate predictions on longer flights.

[FIGJAM 2]

Hey Kyle,

 

Sorry if this is a dumb question, but i am new to both PFPX and ASN.  

 

I have PFPX using ASN as the weather engine.  Or at least i think I do.  The wind data that i upload in the FMC in the Sim differs drastically from what is showing on the nav displays.

 

At first i thought it was the sim time vs the PFPX/ASN.  I ran some tests and it wasn't.

 

If i have read the above and understood it correctly,  am i correct in saying that this is a bug and will be fixed in SP1.

 

Cheers Marc. 

[scandinavian13 5,192]

 

 

am i correct in saying that this is a bug and will be fixed in SP1.

 

Yes and no...

 

If I recall correctly, there was an issue with the weather import where it was grabbing wind out of sequence.  That has been corrected, but it might not fully explain your issue.

 

By "you ran some tests," what do you mean?  ASN and PFPX handle the weather differently.  ASN, from what I understand, uses interpolation and other methods to infer what the wind would be at intermediate altitudes and positions (NOAA only reports wind at certain FLs, and over certain points, so there are gaps between them).  PFPX uses a different method (at least as described by one of the HiFi guys in one of the other threads around here).  Also, I'm not sure how ASN handles this, but I believe PFPX uses forecast wind instead of current wind for waypoints that are farther off in the distance.  Forecast wind might be more accurate as compared to using current wind for a point that's 4 hours away, but forecasts are still just predictions.  If you pulled the wind prior to departure, and are seeing discrepancies 4 hours into the flight, this is to be expected (not as much anymore, though, because you can have the 777 pull the wind again).

[FIGJAM 2]

Hi Kyle,

 

I don't think I was having an interpolation issue.  I am at work now so not on my PC with the sim active to put up some screenshots but I will try explain what was going on.  PS: I watched your 1hr video on PFPX planning hoping to see what i may be doing wrong but i was doing the planning as you were.

 

1. I did my flight plan in PFPX using ASN as the weather then uploaded to the PMDG 777 FMC(this is only referring to the WX)
2. Just after takeoff at the first way-point at cruise so not long into the flight i had drastically different readings.  for example the FMC was showing 360/25 and the actual was 180/76.  So i don't believe it was an interpolation issue or forecast vs actual issue.
3. As i said in my post above i thought it was a sim time vs PFPX planning time but i checked that and there wasn't a difference.

 Could it be the way i am running ASN, unlikely because i set the exact same historical time as when the PFPX flight plan was created it was almost live give or take a few minutes. 

 

The only thing I haven't tried is doing a flight from an airport on zulu time to see if that helps.

[pcubine 143]

Also, I'm not sure how ASN handles this, but I believe PFPX uses forecast wind instead of current wind for waypoints that are farther off in the distance.

Kyle

 

According to post #8 above by kterz ASN does use forecasted winds and not a snapshot of the current winds at waypoints along the route.

[Richard McDonald Woods 168]

As they say - "Read The Fine Manual!"

[pcubine 143]

I now question if the winds in ASN are forecasted or not. I started ASN, loaded a flight plan for KMIA-KSEA which is a long enough flight that you would think wind direction and speed would be different towards the end of the flight at different at a different cruising speed. I used the default speed of 300 kts.  The average direction and speed was 284/19 and average headwind was 11.77. I then changed the speed of the aircraft from 300 to 480 kts and the results were exactly  the same. You would think there would be a difference since you are arriving quite a bit earlier at the latter waypoints.

[pete_auau 1,159]

This is  a sim were are taking about, not real life  situation

[Richard McDonald Woods 168]

I cannot understand why so many are having these wx problems. To me it is simple.

 

When planning a flight, I need to know what are the forecast winds for my chosen route. PFPX does this by estimating when I shall be over each waypoint (given my estimated time of departure), and using forecast data to produce the .wx file, on export, which can be loaded into the FMC. Having done this, the FMC now knows what is the FORECASTED weather en route. No involvement yet by ASN!

 

When flying the route, I need to know what are the actual winds encountered during the flight. ASN injects just this data into FSX. As Trent has said, once started, there is no reason to view the ASN windows because the data is being injected into the sim, and no action is possible/necessary.

 

In PMDG777 SP1, the ability to re-load the weather into the FMC may become possible. But doing this will do nothing other than alter your flight forecasted weather, not the actual weather encountered. This is not logically realistic.

 

Personally, I like to see just how much earlier/later I arrive at my destination caused by differences between the weather forecasts during flight planning, and the actual weather encountered. But then I am trying to get as near as pssible to the real-world experiences.

 

PFPX = forecast.    ASN = actual.

 

HTH

[pcubine 143]

 

 

ASN = actual.

 

But that is not what kterz says in post 8 of this thread. He should know since Damian Clark and he developed ASN. I use PFPX winds for entry in winds pages of the FMC.  I know the conditions the plane encounter are actual not forecasted. However, I get the impression from his post that winds which appear in the flight plan are forecasted. I don't think they are.

[scandinavian13 5,192]

I think we're discussing two issues here:

1. Yes, there is absolutely going to be a difference between planned and actual.  Like it or not, the data that we glean from weather stations leaves large gaps, which is why the guys at HiFi and other weather developers have to create such neat algorithms to assume the weather in between.  Wind is one of those data points that the FAA has been looking into trying to get airlines onboard with the idea of using aircraft as weather sensors to send data back down for better modeling of actual conditions, which helps to enable better forecasts (this, through the concept I worked on a little while back, called SWIM).  As such, no matter how good ASN gets at interpolating values and approximating reality, they're subject to the data available.  Everyone is.  From there, it's a matter of forecasts being forecasts.  They're a best guess, base on the facts available.  We don't have all the facts, so we're limited (see beginning of paragraph).
2. I recall there being some kind of issue with how the wind information was read by the systems, which has been addressed in SP1.  I think the issue tracking thread alludes to it briefly, and indirectly.

...so, part bug, part misunderstanding of forecast versus actual.

[kterz 49]

Hi Michael.

 

After changing the speed did you click refresh so that the etas (and the briefing) are recalculated?