20 minutes ago, coastaldriver said:

I guess when realism was not that important you could get away with approximation

Its not so much that, I've spoken about it on the dev slack, but I dont think they got it.

There is a lack of understanding generally that metar is the weather as measured by a station in the airport, probably a laser pointed up at the sky to measure the altitude of the cloud directly above the airport, temp and humidity sensors etc there.

It doesnt include any weather radar stuff, any element of forecast (e.g. a huge storm due to roll over the airport in 10 minutes wont be in the metar) or any info at all of the prevailing conditions. For that you have to go to the current time in the current TAF.

Initially that sounds like you can just get away with reading the METAR. But you just cant, if the runway has been cleared and the sun is shining over the airport it probably wont even report that a thick heavy snow storm was currently taking a 2 minute timeout when the measurements were taken. And airport locations - especially the big ones generally take account of getting the best of the local weather. and small airports dont even report metars.

I discovered this when all the surrounding metars from the local airport were currently reporting CAVOK, but I didnt see the TAFs were accurately reporting SN,TS,CB and 400 foot ceilings.

Started the engines for a VFR flight before asking ATC permission to start the engines, very expensive mistake I will never make again.

Edited February 8, 20233 yr by mSparks

19 hours ago, coastaldriver said:

Franz this has been the case with all the sims for varous reason. I guess part of the reason is the way Met people report visibility for real - they report the average for the whole sky dome but it could be in one or two sectors only and the rest is fine, the only Metars that fine tune this are the ones that report runway visual range (basically only major international airports). Same with cloud they could be reporting CAVOK but you could have overcast above at 6000 ft. 

It actually worked with XP11 or P3D using Active Sky. Or with xEnviro.

I was talking for example about metars like these:

MMUN 081744Z 12011G21KT 7SM BKN015TCU 28/22 A3006 RMK SLP183 54000 954 8/200 TZAS CI
 

Visibility is supposed to be 7SM. And XP shows it as 22,3 Km or something like that. The difference can be extreme if 1/2SM is reported and XP sets it to over 11km.

10 hours ago, mSparks said:

Its not so much that, I've spoken about it on the dev slack, but I dont think they got it.

There is a lack of understanding generally that metar is the weather as measured by a station in the airport, probably a laser pointed up at the sky to measure the altitude of the cloud directly above the airport, temp and humidity sensors etc there.

It doesnt include any weather radar stuff, any element of forecast (e.g. a huge storm due to roll over the airport in 10 minutes wont be in the metar) or any info at all of the prevailing conditions. For that you have to go to the current time in the current TAF.

Initially that sounds like you can just get away with reading the METAR. But you just cant, if the runway has been cleared and the sun is shining over the airport it probably wont even report that a thick heavy snow storm was currently taking a 2 minute timeout when the measurements were taken. And airport locations - especially the big ones generally take account of getting the best of the local weather. and small airports dont even report metars.

I discovered this when all the surrounding metars from the local airport were currently reporting CAVOK, but I didnt see the TAFs were accurately reporting SN,TS,CB and 400 foot ceilings.

Started the engines for a VFR flight before asking ATC permission to start the engines, very expensive mistake I will never make again.

True. Here in OZ they have replaced human beings doing the observations with a lot of automated systems (This is especially the case for the once magnificent country wide coverage they had from the Post Offices who all reported the weather with proper trained observers -basically every 30 km or so they had a good report. As the Post Offices closed so disappeared the observations and automated systems. All the little airports long ago gave reports away to have automated systems) Problem is that 95% of these systems simply report wind, temp, press and if there has been precipitation (not what type) they cannot do cloud because the equipment cannot do it so you get the dreaded words on such metars as AUTO and NCD (No Cloud Discernible). Or if the weather was done by the Tower, tower closes they switch to auto and in a lot of cases even with the tower they are still only reporting the auto generated metar and if they get around to it might add in to the metar some remarks about the humungous CB to the west or similar. 

Area Forecasts are still good as are the TAFs but the Metars basically at best a guide and really only useful for wind and the QNH.  

So it is a bit of a curates egg to work with to create sim weather!

Well, although all of my test flights have taken place around Lisbon, truth is the weather was spot on all of the time, including clouds being depicted to the North of LPPT because they were being reported between FEW and SCT while at LPMT it was CAVOK.

Wind direction, intensity as well as pressure was spot on according to METARs.

Turbulence was ok - better than the silly turbulence we have in MFS, specially after a few weeks 😕