(1) Metar winds are given in TRUE (From) Directions, in speed units of Knots (Worldwide)
(2) Atis is spoken, and given in MAGNEIC, and is in Knots
(3) GPS indications of WInd Directions are given in Magnetic (this is what the pilot is interested in)
Atis wind direction (spoken) should be Magnetic, but seems to be TRUE ?
Atis WInd speed is being incorrectly given in ft/sec !!
SiMconnect variable AMBIENT WIND DIRECTION (degrees) does not specify True or magnetic, but seems to be TRUE ?
BUT, In Asobo Js, sometimes it is calculated with a Magnetic Plane heading, so one assumes it is considered to be magnetic, so it should be the same as the ATIS (magnetic) direction … but is not.
Does not help that the UI, has an ARROW that indicated the DIRECTION of the wind, not where it is coming from, (coming from being s the normal Aviation way of referring to Wind Direction in Aviation)
And all this before considering what REX Weather Force 2020 “might” be adding to the confusion.
I AM SO CONFUSED with this now, the more I look into it !!
However if the code base is from FSX, this is not handled this way internally. Instead, it is using a table of function pointers and/or a table of scalars, and you have to explicitly call a unit conversion function like this (which means you can mess up with ‘from’ and ‘to’):
double convert_units(double value, Unit from, Unit to);
Sadly, wind is a wonky thing. It’s ‘unsimulated’. I sat in an aircraft last week with the wind sock showing an opposite wind to what ATIS was reporting and the wind indicator on the G1000 showing a perpendicular wind. None matched real world. So who knows what runway was appropriate.
ATIS: Wind speeds are DEFIANTLY being announced on radio in units of Feet/sec !!
Is there a SimConnect VAR for “Dewpoint” ???
Visibility reported in Atis does not correspond to SimConnect AMBIENT VISIBILITY ??
And users are wondering why the SIM is not appearing to depict “REAL WEATHER” !!
On a more Positive Note: REX Weather Force does seem to be getting CURRENT Metars (at least in the USA), that correspond to those obtained from other real time online services.
Is it able to correctly Inject that weather into the Sim – Who Knows, as the sim cannot even Inject its own SIMULATED weather for the weather UI correctly.
FUBAR - to put it mildly … and a seemingly total lack of interest or concern from the MFSF community - Obviously other thing like “minor scenery Eye Candy errors” are far more important than Aviation weather.
UI has winds set to 10 knots
Simconnect has it at 5 (units ? ) I am requesting knots
ATIS has it as 17 ( which is 2x the ft/sec speed of the simconnect 5 if that 5 is knots)
My take is
UI is calibrated to a scale of x2 the wind actually being injected into the sim. This is further confirmed by parking the plane into a high (steady) wind, and looking at the airspeed, that indicates about 50% of what the UI is set for.
ATIS is announcing the injected wind speed in ft/in , not knots
So 2 errors contributing to this mess.
Thats it !!! back to CLEAR SKIES, until Asobo gets this mess cleared up.
There is little point in flying in windy weather, if Atis is reporting winds so incorrectly.
( unless you just want to fly about wildly without a clue as to what conditions you are flying into)
Some of this may well have got messed up when Asobo made the Gust settable to go down to zero, as before they may well have been DOUBLING the Wind speed and then adding +/- the gusting to that, that had a min of 50% of the wind speed … !!
There’s some kind of friction layer being simulated, and the friction reduces the windspeed you set in the Weather UI by a half at the surface, and it ramps it up to 100% of the set value at exactly 1000 feet. It’s asinine because you’re specifically trying to set the surface winds, and the simulator overrides it. Sure, you could just set the winds 2x higher to get the surface wind you want. But then you’ve got twice that wind speed at pattern altitude. Trying to practice some really strong crosswind take-offs and landings? Well you get to add some crazy wind shear on top of it. So have fun with that! lol
No, and as far as I know, the simulator has no implementation at all for dewpoint. The value reported by the ATIS is just a placeholder default value. Ideally, you’d be able to set this in the Weather UI and it would affect things like visibility, engine performance, icing, etc, but it’s just not there. One of the biggest gaping holes in the weather system.
Yeah, which I was I loathed even suggesting it and why I cringe every time somebody on here is like, “Make sure you report it to Zendesk! :D”
The actual way to report something is to just keep banging on the drum as loud as you can until they stop what they’re doing and tend to that issue.
With the exception of maybe the ft/sec units conversion bug, all of the above identified issues were reported during the Alpha testing of the simulator. It’s probably just on their infinitely long TODO/backlog. For reference, here’s a detailed discussion about the 50% surface winds issue:
The wind is “measured” at the surface ( up on a Tower) with a Wind sensor, and that is the Ground Wind, that is given to the pilot in the ATIS, and is what is used in the Metar.
What the wind is doing up at 1000ft or above is another matter and is, by definition, the wind at 1000ft.
Unfortunately, this is just another example the development of simulation software, that is not simulating Real World, but instead what some Game Developer “THINKS” will be appropriate, or is within their limited understanding.
The logic should be the other way around. You should be Punching in the GROUND wind, and then the geostrophic wind (wind above the friction layer) should be (attempted to be) calculated from “Measured” GROUND level wind speed.(and direction)
The “Geostrophic” wind is NOT the wind that :
The windsock is subjected to
The Plane on the ground, during talkeoff and Landing is subjected to
The Wind that is measured by the Ground based Winds sensors , used by ASOS & AWOS.
The Wind that is used to form the ATIS and the METARS
This is really a case of “A little knowledge being a bad thing”.
Having gained a little knowledge about the existence of “Geostrophic winds”, the simulator developer seems to have used that in a totally inappropriate way, by making assumptions that are not in fact how things work in the “Real World”.
In the GAMES world, doing this may be to some “acceptable” , but in a simulator, its just WRONG.
It needs to be corrected . (Please)
It might also behoove some to research exactly what GEOSTROPHIC WINDS are.
GEOSTROPHIC WINDS blow above the friction layer of the Earth, balanced between pressure gradient forces and the Coriolis force. Geo, meaning “Earth,” and strophic, or “turning,” refer to the Coriolis force of the Earth’s rotation.
And, of course, the ATIS reporting wind speeds in ft/sec is just 100% wrong, and one would hope that that is “quietly” corrected in the next update, probably with the least said the better. !
I took off from CYVR this morning. ATIS said wind out of 090 at 20kts, so ATC clears me to taxi to runway 27L? The wind sock shows strong wind out of 090-ish. My wind indicator on the instrument panel shows something else entirely.
It seems like 95% of the time, the active runway is always the reciprocal of what it should be. ATC always is clearing me to land with a tailwind.
To clarify (July 2021) a couple of the issues in this thread:
SimVar (A:AMBIENT WIND DIRECTION, degrees) is in degrees TRUE, and represents the direction the wind is coming FROM.
Windspeed (A:AMBIENT WIND SPEED, knots) is reduced near the ground relative to the value shown in the Weather UI. Approx: Zero feet AGL = 50%, 200’ = 70%, 500’ = 90% of ground (wind + gust) given in settings.
When manually setting wind I personally use at least 2 layers that cover the flight altitudes rather than guessing what MSFS will do above the highest wind layer - in particular I never have only a single wind layer set at ground level.
These comments are just re. setting the wind and using those vars i.e. not related to in-game ATIS/METAR/Live Weather.
This wind gradient is significantly dependent on surface features & types, which also might be far easier to cater for, by starting off at the Ground level (measured speeds by surface Instruments) and then adjusting as one increases altitude.