Temperature layer distortion when writing visibility

[metamarty]

Hello,

 

In my current instructor station, there is an option to change the visibility. This works by writing offset 0f8c directly. We want to use the old weather interface because we are not interested in providing a full set of weather, but only want to change a single aspect.

 

When writing to this offset, the temperature layers become distorted and seem to have an OAT of 15 degrees at all altitudes, leading to TAT values over 40 degrees at higher altitudes. Strangely enough, this is fixed by clicking on the World menu in FSX, then clicking Weather and then clicking OK. After this fix, the OAT follows correct ISA changes at higher altitudes. The temperature layers themselves, when examined in the weather menu do not appear different before and after the fix.

 

I have observed this in FSX, FSUIPC version 4.921f. 

I'm using global weather set to "Fair weather".

With FSInterrogate, I read offset 0f8c, which shows 6214.

With FSInterrogate, I write 3000 in the field, after which the weather mode jumps to User-defined, which is expected and at this point the temperature layers are incorrect and the OAT is 15 degrees at all altitudes.

When then clicking on World, Weather, OK, the temperature is correct again.

 

I'm basically happy with how the weather operates, as long as I can force FSX to correct the temperature layer. Preferably without writing my own temperature layers (as they may have been set by external weather tools).

 

Is this a known issue, and is there any way to force the re-initialization of the weather system that happens when clicking Word, Weather, OK?

 

Many thanks,

 

Marty

 

 

 

[Pete Dowson]

In my current instructor station, there is an option to change the visibility. This works by writing offset 0f8c directly. We want to use the old weather interface because we are not interested in providing a full set of weather, but only want to change a single aspect.

 

When writing to this offset, the temperature layers become distorted and seem to have an OAT of 15 degrees at all altitudes, leading to TAT values over 40 degrees at higher altitudes. Strangely enough, this is fixed by clicking on the World menu in FSX, then clicking Weather and then clicking OK. After this fix, the OAT follows correct ISA changes at higher altitudes. The temperature layers themselves, when examined in the weather menu do not appear different before and after the fix.

 

I have observed this in FSX, FSUIPC version 4.921f. 

I'm using global weather set to "Fair weather".

With FSInterrogate, I read offset 0f8c, which shows 6214.

With FSInterrogate, I write 3000 in the field, after which the weather mode jumps to User-defined, which is expected and at this point the temperature layers are incorrect and the OAT is 15 degrees at all altitudes.

When then clicking on World, Weather, OK, the temperature is correct again.

 

I'm basically happy with how the weather operates, as long as I can force FSX to correct the temperature layer. Preferably without writing my own temperature layers (as they may have been set by external weather tools).

 

Is this a known issue, and is there any way to force the re-initialization of the weather system that happens when clicking Word, Weather, OK?

 

Sorry, I've no idea. Can you enable weather logging, in the FSUIPC logging tab, and see what METAR string is being sent as a result of you changing the visibility? (Remember, FSUIPC has to set the ENTIRE weather each time you change one little thing, because SimConnect only accepts the full extended (FSX format) METARs)

 

I would suggest comparing the last METAR read with the one then sent, but they are not directly comparable because the format for reading is different to that for writing!!! Grr.

 

Pete

[metamarty]

Here's a piece from the log file when I write to 0x0f*C with FSInterrogate:

   803452 Weather Received (type 4 request, Interpolated): "????&A0 221523Z 30125KT&D900LG 295V307 100KM&B-457&D30936 1CU032&CU001FLLN000N 6CI327&CI001FNMN000L -27/-30 Q1010 "
   803452 WX Received in (0 mSecs), WX request type 4, Lat=52.0789, Lon=4.7524, Alt=7597.6m
   803827 >NewSet:  **** New Weather being set: ICAO=GLOB (Dyn=0)
   803827 >NewSet:  Pressure=999.5, Drift=3.0
   803827 >NewSet:  Visibility[0]: range=62.1sm (100005m), from=-1490ft, to=6000ft
   803827 >NewSet:  Temperature[0]: alt=215010ft, Day=18 C, NightVar=3 C, DewPt=12 C
   803827 >NewSet:  Temperature[1]: alt=3270ft, Day=5 C, NightVar=3 C, DewPt=4 C
   803827 >NewSet:  Surface wind: to alt=2950ft AMSL, dir=301T, vel=10.00, gust=0.0, turb=0, shear=0, var=2.0
   803827 >NewSet:  Wind layer 1: to alt=3270ft AMSL, dir=301T, vel=25.0, gust=0.0, turb=1, shear=0, var=0.0
   803827 >NewSet:  Cloud[0]: type=9, from 3270ft to 6550ft (+/- 100ft), cover=1, turb=1, topshape=0
   803827 >NewSet:                      Precip=0, base=-1480ft, rate=0, icing=0
   803827 >NewSet:  Cloud[1]: type=1, from 32800ft to 34570ft (+/- 100ft), cover=8, turb=0, topshape=0
   803827 >NewSet:                      Precip=0, base=-1480ft, rate=0, icing=2
   803827 >NewSet:  **** End of New Weather details for ICAO=GLOB
   803827 Setting Weather: "GLOB 221523Z 30110KT&D900NG 300V302 30125KT&A900LG 100KM&B-456&D2284 1CU033&CU033FLVN-14N 8CI328&CI018FNVN-14L 18/12&A65534 05/04&A997 Q1000 "
   803842 Weather Mode now = Global
   804607 Weather Read request (Global set) to area 1: ICAO="GLOB", Req=0
   804607 Weather Received (type 1 request, (null)): "GLOB&A0 221523Z 30110KT&D900NG 300V302 30125KT&A900LG 100KM&B-456&D2284 1CU033&CU003FLVN000N 8CI328&CI001FNVN000L 18/12 05/04&A997 Q1000 @@@ 30 6 301 25 | "
   804607 WX Received in (0 mSecs), WX request type 1, ICAO=GLOB
   804607 >Change:  FS98 Pressure=1000.0 mb
   804607 >Change:  FS98 Wind1: 2936ft to 6270ft AMSL, dir=300T, vel 25, gust 0, turb 64
   804607 >Change:  FS98 Vis: range =62sm, (raw value=6214)
   804607 >Change:  FS98 Cloud1: type=9, from 3200ft to 7200ft (+/- 0ft), cover 1, turb 72, ice 0
   804607 >Change:  FS98 Cloud2: type=1, from 32700ft to 32900ft (+/- 0ft), cover 6, turb 0, ice 2
   804607 >Change:  FS98 Temp0: to 0ft, Day -27.0C, NightVar 0.0C
   804607 >Change:  FS98 Temp1: to 3270ft, Day 15.0C
   804607 >Change:  Pressure=1000.0 mb
   804607 >Change:  Wind layer 1: to alt=5950ft, dir=301T, vel=25.0, gust=0.0, turb=1, shear=0, var=0.0
   804607 >Change:  Visibility[0]: range=62.1sm (100005m), from=-1490ft, to=6000ft
   804607 >Change:  Cloud[0]: type=9, from 3300ft to 7300ft (+/- 0ft), cover=1, turb=1, topshape=0
   804607 >Change:                      Precip=0, base=0ft, rate=0, icing=0
   804607 >Change:  Cloud[1]: type=1, from 32800ft to 33000ft (+/- 0ft), cover=8, turb=0, topshape=0
   804607 >Change:                      Precip=0, base=0ft, rate=0, icing=2
   804607 >Change:  Temperature[0]: alt=0ft, Day=18.0 C, NightVar=0.0 C, DewPt=12.0 C
   804607 >Change:  Temperature[1]: alt=3270ft, Day=5.0 C, NightVar=0.0 C, DewPt=4.0 C
   804607  Results: FS98 Pressure=1000.0 mb
   804607  Results: FS98 Wind1: 2950ft to 5950ft AMSL, dir=300T, vel 25, gust 0, turb 64
   804607  Results: FS98 AmbientWind at PlaneAlt=24925: dir 301T, vel 18
   804607  Results: FS98 Cloud1: type=9, from 3300ft to 7300ft (+/- 0ft), cover 1, turb 72, ice 0
   804607  Results: FS98 Cloud2: type=1, from 32800ft to 33000ft (+/- 0ft), cover 8, turb 0, ice 2
   804607  Results: FS98 Temp0: to 0ft, Day 18.0C, NightVar 0.0C
   804607  Results: FS98 Temp1: to 3270ft, Day 5.0C
   804607  Results: FS98 CurrTemp at PlaneAlt=24925: 18C
   805761 Weather Read request (Global set) to area 1: ICAO="GLOB", Req=0
   805761 Weather Read request (Nr Station) to area 5: Lat=52.08, Lon=4.76, Alt=0.0, Req=1
   805777 Weather Received (type 1 request, (null)): "GLOB&A0 221523Z 30110KT&D900NG 300V302 30125KT&A900LG 100KM&B-456&D2284 1CU033&CU003FLVN000N 8CI328&CI001FNVN000L 18/12 05/04&A997 

I don't think there's anything special regarding the temperature, yet after this write, the temperature at all altitudes is 15 degrees. The strange thing is, that you cannot get FS to do this using the normal weather menu's. Even if you remove all of the temperature layers in FS, it will result in a temperature that is 15 degrees at ground altitude and going down when you increase altitude. This behavior is in both FSX and Prepar3d.

 

Edit: This might be the problem:

 

803827 >NewSet: Temperature[0]: alt=215010ft, Day=18 C, NightVar=3 C, DewPt=12 C

[Pete Dowson]

Here's a piece from the log file when I write to 0x0f*C with FSInterrogate:

 

Ah, you aren't setting GLOBal mode BEFORE setting weather? So when it autimatically switches to GLOB weather it has to use some weather which you've not set before but which just happens to be the default GLOB weather at the time.

 

The received / sent / received strings from your extract are just these:

 

Weather Received (type 4 request, Interpolated): "????&A0 221523Z 30125KT&D900LG 295V307 100KM&B-457&D30936 1CU032&CU001FLLN000N 6CI327&CI001FNMN000L -27/-30 Q1010 "

 

That's just the interpolated weather at your current altitude -- only one temperature (-27/-30 ??), one wind layer. But it isn't the default GLOB weather which would be used to populate as yet unset weather stations.

 

Setting Weather: "GLOB 221523Z 30110KT&D900NG 300V302 30125KT&A900LG 100KM&B-456&D2284 1CU033&CU033FLVN-14N 8CI328&CI018FNVN-14L 18/12&A65534 05/04&A997 Q1000 "

Weather Mode now = Global

Weather Received (type 1 request, (null)): "GLOB&A0 221523Z 30110KT&D900NG 300V302 30125KT&A900LG 100KM&B-456&D2284 1CU033&CU003FLVN000N 8CI328&CI001FNVN000L 18/12 05/04&A997 Q1000 @@@ 30 6 301 25 | "

 

So the setting is being set. But notice that most of the values are different -- eg QNH is now 1000 not 1010. Your temperatures at your location were -27/-30 (??), but the default global at ground were 18/12. These entries "18/12&A65534 05/04&A997" are odd. There are two layers being set, but altitude 65534 can't be right -- that's probably -2. Are you over a place below sea level? It does seem to have been accepted okay though as the 18/12 was returned ok as was the next layer, 05/04.

 

The default GLOBal weather does not usually fearure layering, so i'm surprised really that there are two temperature layers included here.  But I'm perplexed as to why the correct temperature gradient was not applied until you went into menus. that's another FSX weather bug to add to all the rest!

 

There are some possible ways out of this:

 

1. Set GLOBal mode before trying to change anything.  I suspect this won't give you what you expect though. But worth a try.

2. Either use the AWI interface, which does allow you to make individual changes, or the NWI, which is more comprehensive.

 

To be honest, I'm really surprised anyone is still using the FS98 offsets. I have tried to make them work compatibly, and mostly achieved this in FS9, but FSX is a completely different kettle of fish. Sorry.

 

Regards

Pete

[metamarty]

Thank you for the clarification. I was flying over Rotterdam, so the negative altitudes are correct. 

 

Basically, the intructor station that issues the visibility changes does not yet have a complete weather interface and that's why I didn't bother to fill in a complete weather update, but simply tried to change only the visibility. This is done by accessing only the f8c offset regardless of the current mode of the weather system.

 

I now believe this approach is not feasible. A complete weather system is planned anyway in the instructor station, so I guess the best approach is a cycle to read current metar, apply changes and submit an entire metar again. This will be part of a much more sophisticated weather system that tracks the current weather mode and applies changes either locally or globally. 

 

I know what to do.

 

Thanks,

 

Marty