PFPX winds vs ASN winds

[Richy 1]

Hello,

 

First of all, sorry for my English, it isn't my native language ;-)

 

When I plan a flight with pfpx (with ASN weather selected at the options) the winds aloft are quite different. It's still in the planning phase so there can't be a difference between planning vs. actual winds.

So after pfpx computed my flight I save it and load it inside ASN --> flight plan. At some waypoints (FL240) the difference is about 20kts (290/20 and 290/38). The wind direction always matches, it's just the wind speeds which are always 'off'.

 

I hope someone sees what I'm doing wrong here.

 

Regards 

[g_precentralis 191]

Well, they should use the same source. The difference may be in time of forecast or in interpolation technique. 

[Richy 1]

Thanks for your quick answer. I personally think it's the interpolation technique then. Guess I just have to live with it..  :lol:

[Richy 1]

If I open ASN and check the winds aloft at LGMK (Mikonos Airport, Greece) then the wind at FL300 is 281/81, and when I check it inside pfpx (with ASN as wheather source) it shows 279/50...

That's a way too large gap  :unsure: .

Again, the direction is constantly spot on, but the speeds are way too variable!

 

Any help would be much appreciated.

 

 

EDIT: The STD (Scheduled Time of Departure) is set to the current UTC time. So it's not a forecasted wind!

[g_precentralis 191]

Wind chart shows about 275/60 to 65

[Richy 1]

With ASN as weather source pfpx shows 280/48 FL300 overhead Mykonos (LGMK)

With pfpx itself as weather source it shows 255/81 FL300..

 

ASN itself says 280/81 FL300.

 

Doens't make any sense to me :wacko:

[g_precentralis 191]

:lol:

 

Simbrief gives 268/072 for LGMK at FL300

[kterz 49]

Hi,

 

well, there may be an explanation: They may read the wrong layer from current_wx_snapshot. Does it match to a neighbour layer? 

[Richy 1]

HI!

 

PFPX wind chart (ASN as weather source)

FL200  291/32

FL250  285/38

FL300  280/48

FL350  271/55

FL400  266/60

 

ASN LGMK

FL180  290/24

FL240  282/30

                           <------- note this 50kts gap

FL300  280/80

FL340  270/93

FL390  260/92

 

 

So it does not match a neighbour layer ;-)

[kterz 49]

Hi,

 

as I understand this PFPX uses current_wx_snapshot.txt  file exported by ASN when using it as a source. Now, in this file, the aloft data are sorted as seen in ASN's conditions page (3k, 6k,9k,12k,18k,24k,30k etc), but there is no indication of the flight level they refer to (this is something you can check for yourself).

 

From this point on, I don't know how PFPX parses these data. My initial thought is that there is a mismatch in layers, but I can't test/confirm further because I don't use PFPX (yet).

[Richy 1]

Maybe I can try to delete the current wx_snapshot file to let ASN build a new one?

[kterz 49]

ASN builds a new one whenever it downloads new data anyway, so this shouldn't be needed

[Richy 1]

Ah, my bad!

I checked the wind aloft at and around Schiphol Amsterdam (EHAM) and those winds are right on spot compared to the ASN condition tab!

Maybe Mykonos is just an 'inaccurate' region? I'll check other regions in about a few hours and I'll give an update here ;-)