Visibility trouble

[dave jones]

I know Pete is off on holiday for awhile, but perhaps someone who is much more familiar with this topic than I can help out.

To start with, I'm talking about FS9, using it's own (global) weather, and FSUIPC version 3.71.

Like many others, I want to get past the problem of suddenly bursting into clear blue sky above and below as you climb out of FS's own visibility layer which I have set at 8500 feet. I've read the documentation on the subject a dozen times at least, and experimented with all the values with no success. When I climb out of FS's visibility layer, I now get a drastic and rapid -- but not instantaneous -- lightening due to haze of all the ground below both near and far. Then, climbing another 1000 feet, the horizon snaps into view. I know this can work because it does for so many others. There has be something very fundamental that I'm not getting. Here's the relevant section of my .ini file:

GraduatedVisibility=Yes

LowerVisAltitude=0

UpperVisAltitude=22000

UpperVisibility=6000

GenerateCirrus=Yes

WindShearSharp=No

UpperWindGusts=Yes

ExtendMetarMaxVis=Yes

PatchSimApAlt=Yes

DisconnTrimForAP=No

ZeroElevForAPAlt=No

AutoClearWeather=Yes

ExtendTopWind=No

WindSmoothness=5

SmoothPressure=No

PressureSmoothness=5

SmoothVisibility=Yes

VisibilitySmoothness=4

MaxSurfaceWind=0

WindLimitLevel=200

WindDiscardLevel=400

WindAjustAltitude=No

WindAjustAltitudeBy=2000

MinimumVisibility=0

MaximumVisibilityFewClouds=6000

MaximumVisibility=2000

MaximumVisibilityOvercast=2000

MaximumVisibilityRainy=1000

OneCloudLayer=No

ThinClouds=No

ThinThunderClouds=No

CloudThinness=1000

ThunderCloudThinness=10000

CloudTurbulence=Yes

CloudIcing=No

WindTurbulence=No

SuppressAllGusts=No

ExternalOptionControl=Yes

AutoTuneADF=No

KeepFS98CloudCover=No

ShowPMcontrols=No

MagicBattery=No

RudderSpikeRemoval=No

ElevatorSpikeRemoval=No

AileronSpikeRemoval=No

ReversedElevatorTrim=No

StopAutoFuel=No

TrapUserInterrupt=Yes

NavFreq50KHz=No

ClockSync=No

SmoothIAS=Yes

SetVisUpperAlt=No

VisUpperAltLimit=4000

MaxIce=-4

MinIce=-4

WindSmoothingDelay=0

WindSmoothAirborneOnly=No

LimitWindVariance=No

VisSmoothingDelay=10

VisSmoothAirborneOnly=Yes

Also, it would be helpful if someone could tell me:

What is the difference between the "upper visibility" on the lower right of the visibilty setting page and the "upper altitude of restricted visibility" to the left? I just don't understand the documentation about this.

What does the "smooth only when airborne" box do?

What is the box for that says "but after weather cleared, delay...?

FSUIPC is a wonderful set of tools and this visibility bit is fascinating, so I'd really like to get to understand it fully and make it work.

Thanks for any replies! ...Dave

Dave Jones

Fort McCoy, Florida USA

[Frank.O]

Good morning Dave,

Like many others, I want to get past the problem of suddenly bursting into clear blue sky above and below as you climb out of FS's own visibility layer which I have set at 8500 feet. I've read the documentation on the subject a dozen times at least, and experimented with all the values with no success. When I climb out of FS's visibility layer, I now get a drastic and rapid -- but not instantaneous -- lightening due to haze of all the ground below both near and far. Then, climbing another 1000 feet, the horizon snaps into view. I know this can work because it does for so many others. There has be something very fundamental that I'm not getting.

it's been a long time since I tinkereed with these things, and I have it not quite to my satisfaction yet either. The best you can achieve is when setting reasonable vis limits on the ground for the four different weather conditions (the four top left values on the vis tab) and use visibility smoothing and graduated visibility. To avoid seeing a sharp horizon set the upper vis limit (downmost value on the right side of the vis tab) to no more than 30 miles. This is fine for GA flying but I learned from Pete that it can be unrealistic at times when flying at high altitudes because sometimes a sharp horizon is seen there.

A vis layer setting up to 8500 feet seems a bit high for me. Try a lower setting and set the starting of graduated vis to Zero (top of the three lower values on the right) so it starts graduating at the top of FS's own vis layer. The upper value (where the graduating stops) can be left at 25000 and the upper limit should read 3000 if you don't want the sharp horizon. Check smooth visibility and leave it at 10% every 2 seconds.

What is the difference between the "upper visibility" on the lower right of the visibilty setting page and the "upper altitude of restricted visibility" to the left?

The one on the right is the maximum vilibility at high altitude and it is set by FSUIPC. The left one is the altitude where FS's own layer of restricted visibility ends.

What does the "smooth only when airborne" box do?

Exactly what it says I think. It deactivates the smoothing as long as you are on the ground.

What is the box for that says "but after weather cleared, delay...?

It delays the smoothing for so many seconds after all weather was cleared which can also be done by an external weather program. This is useful if you (or the weather program) deliberately changed the weather and want your changes to be applied fast so that you are ready to start flying.

Hope this is of some use to you.

Regards,

Frank

[dave jones]

Yes, Frank, that is of a lot of use to me. Sounds like what I'm doing is about right but I will try lowering the upper visbility. Actually, I don't mind seeing the horizon at high altitude -- what I don't like is the way it suddenly pops into view. Yes, I did understand that the lower visibility altitude needs to be zero and I had fooled with the upper limit of FS's own haze layer but the effect did not change. I'll mess with it some more.

The main thing is that I'm apparently not doing much wrong; it's just that there is no utopia. Perhaps a better answer would be to make sure there's always a scattered (at least) cloud layer at the altitude where you transition from FS's visibility layer into FSUIPC's graduated layer above?

Thanks very much for your help, Frank. Of course any other tips would be most welcome also. Back to the experiments...

...Dave

Dave Jones

Fort McCoy, Florida USA