Visibility reporting from Canadian stations

[mike2060 4]

Hi,

 

Most AUTO reporting stations in Canada only report visibility up to 9SM. So when they report 9SM it could be 30SM. Also, Canadian reporting stations that are not AUTO usually report up to 15SM. It seems in OpusFSX, 9SM reported is taken to mean 9SM exactly and the same with 15SM.

 

I believe any stations that begin with CY and have AUTO in the METAR report up to 9SM, and any stations that begin with CY and don't have AUTO in them report up to 15SM.

 

I am not sure how hard that would be to change this but just an idea.

 

Thanks,

 

Mike

[Opus Software 84]

Hi Mike,

 

I though they used 10SM to imply no visibility restriction, just like the USA and a few other places.

 

It was my belief that the USA and Canada use 10SM to imply 10SM or better, and the rest of the world mostly use 9999 to imply 10km or better.

 

In each case OpusFSX substitutes your specified Default Surface Visibility specified in the Weather Preferences dialog.

 

I will have to confirm the 9SM usage as this is news to me and would make Canada different from all other standards.

 

Stephen :smile:

[mike2060 4]

Thanks for the reply Stephen,

 

Yep, just head over to skyvector.com and take a look. AUTO stations use up to 9SM and normal airports use up to 15SM (which makes pretty much all Canadian airports have a surface visibility of 15SM max).

[Opus Software 84]

Thanks Mike,

 

I will change the interpretation for Canadian Met stations and METARs and post them in the next OpusFSX Release and OpusFSI Beta, I will post them very soon (next week as its a public bank holiday weekend here in the UK).

 

Stephen :smile:

[mike2060 4]

Thanks a lot!

 

To make things a bit more complicated there are some stations that report visibility up to 40SM. I have made a list of them and what their max reported visibility is:

 

CYMA 20
CYDA 20
CYQQ 20
CYZT 20
CYYD 25
CYGH 25
CYXC 25
CYQU 25
CYBG 25
CYMX 25
CYQB 30
CYYE 30
CZFA 30
CYDB 30
CYVR 30
CYVQ 30
CYZV 30
CYGH 30
CZFM 35
CYYC 40
CYXY 40

 

I don't know what it takes to filter these out of the rules you have set up but that would be the easiest in order to prevent a greater visibility to be set when the reported visibility is actually 15SM.

 

Hope this helps.  Thanks again!

[Opus Software 84]

It does help, thanks Mike.

 

I will look into incorporating a list of known deviations so that the correct max reported visibilities can be factored in. I will see about incorporating it in as soon as I can. If there is a more extensive list though I may have to allow it to be specified separately, or held in a text file or something.

 

Regards

Stephen

[Opus Software 84]

I have implemented the above and changed the decoding software in both OpusFSX and OpusFSI to both recognise and accept any Met station that reports visibilities greater than the usual 10,000m or 10SM standard. I will post these changes in the next OpusFSX and OpusFSI Betas.

 

Stephen

[Opus Software 84]

Beta Version 3.47.3 has been posted.

 

Stephen

[mike2060 4]

Wow, that was quick! Thanks a lot Stephen!

[mike2060 4]

Since I have this thread open I just had another question. I was wondering why OpusFSX chooses to display stratus for clouds above 25000 and not cirrus? I only ask this because in Canadian METAR we have the cloud types so I can see that most times clouds at 25,000+ are cirrus.

[Opus Software 84]

Simply because we have not implemented the Canadian cloud type statements.

 

Also the sim is very limited when it comes to cloud types, there is only one bitmap texture for cirrus so if you are not careful you will end up seeing double. Also there is no way to specify the number of octas for that bitmap, its either on or off.

 

Hence, At the moment the LWE will only depict cirrostratus or cirrocumulus clouds which have greater bitmap choice.

 

Stephen

[mike2060 4]

OK, thanks for explaining. Makes sense. I knew there must be an explanation for it.

[Opus Software 84]

We have implemented the Canadian cloud statements in the RMKs section but only interpret the non-cirrus cloud definitions.

 

In the sim, FSX and P3D, there is only provision for a single sky and cirrus cloud texture.

 

So if you want to match the upper atmosphere sky colour and cirrus texture you must load an appropriate sky and cirrus cloud texture before running the simulator. After that you can configure your preferences in the Opus Weather Preferences dialog, turning cirrus on or off as desired and even specifying the altitude.

 

Alternatively you can leave cirrus on Auto and let the LWE decide. The LWE will sort of mimic real life and enable cirrus when it sees that the weather across the weather map is quite changeable or indicating an approaching storm front. In the RW, cirrus is usually an indicator of changeable conditions and can precede weather fronts by up to 24 hours. We cannot do that in Auto, but we do mimic the real world in the best way we can.

 

So in Auto, if you see cirrus then the conditions are quite changeable but only within the bounds of the Opus 800 x 800 mile weather map.

 

Stephen :-)

[mike2060 4]

Thanks for the tips Stephen.

[mike2060 4]

I just noticed CYUL reports up to 30SM which wasn't on that list I gave you. It is a popular airport (FlyTampa's CYUL) so I thought you should know that.