IF Weather

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IF Weather

Postby Andayle » Sun Oct 07, 2018 11:26 am

Hi all,

I have the date set to today and I did a flight from EGSS to LIPQ, however, the temperature at departure was 24C, is this just random or does the temp get generated on time of year and position? as it seems a little warm for this time of year in the UK.

I have my AI set on 50 planes and early AI set to on, all my AI aircraft are ticked in the AI selection but none seem to show up during the flight. Could this be because I load the IF flight manually from the P3D load menu rather than clicking the fly now button when I use the fly button on IF P3D fails to load?

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Joined: Tue Apr 03, 2012 4:12 pm

Re: IF Weather

Postby Steve Waite » Sun Oct 07, 2018 11:41 pm


Thanks for the questions...

There's lots more to read on these questions and much more in the Help - at any time press F1. So I'll try to add to that information here rather than repeat more mundane stuff from the Help...


The weather injected is 'procedurally generated', that means the same time and day and year, and same settings in the weather page, produce the exact same conditions. You can try by generating another flight elsewhere the weather is different, then come back and generate the first, it should be exactly the same again as before. If not - why not? So we would look into that.

There's no additions or any alterations to the simulation, the weather is as standard as can be maintained for a fully operational atmosphere that is repeatable. That's simply how IF is designed - to make no changes to the sim to accomplish special effects or other things. There's no additional cloud setup to mimic the appearance of the cloud in the same location in that sense, and there's no added contrails and mist or other things, it all appears, contrails and all, through the generated weather from the sim after the injection cycle from IF.

The weather therefore injects no randoms and avoids setting up the system to be randomisable of any kind. However the simulation does do alterations to the way that weather interacts with other weather cells (IF produces 330Nm radius weather system cells), the weather between cells is interpolated by the simulation. Depending on the route and speed through cells taken, this can alter the weather slightly as you come upon it.

The way the temperatures are defined in the algorithm are through a simple 'curve pair' running between generalised min and max temp extremes (oat). These adjust depending on time of day, time of year, latitude and some longitude. The curves maintain a realistic drop in temperature during ascent and descent which is more important than temps right near the ground. Use the data recording facility to check out the temperature curves during ascent and descent. There's one demonstrated on the IF page ".csv file", shows a temp gradient along with the ascent gradient from a flight in FSX.

To maintain a perfect temp near the ground for any general location with no data is not just difficult, maybe it is impossible without locational influences. So instead, IF worries less about seeing a few degrees higher or lower at my favourite airport, that's to be expected to achieve this kind of non-random system. Instead, closer adherence to the temperatures and atmosphere above the ground are given priority.

In short you may see 24C on the ground and maybe you would feel more comfortable with 19C at a particular airport, but the other way at another. I tried a few times of day on your route and saw 19C at 08:00, maybe for that region a little high, in France by noon maybe a little low at 22C. So a 'discrepancy' at any location to its real weather data download is to be expected - we might see a temp picked near one or other extreme edge of the 'curve'.

IF generates an internal map from the procedure and from that picks the weather condition from the location in there. If IF actually downloaded real weather data it can fill that map with real locational values so the locations show the exact weather. That's not a part of IF for the time being, IF concentrates on being an off-line app and avoids additional resource allocations from the internet - although vpilot and VATSIM are well served with the export facility on the flight gen page.

When saving a flight the location may be somewhere between two nodes, when the flight is reloaded the weather is from the last node or the next if closer. After that reloads look the same. Generally you'll see the clouds shift, a little from that saved location when you restore.


Although there are many ways to start a flight and use IF, the way to operate most of the features is to start the flight from the Fly! button - the only way to guarantee starting without being prior-influenced by what's gone before. We might see a typical error coming from an addon that stops the sim working properly in all aspects and we see an IF function unable to work - we need to look at the system.

So let us look at what IF does to start a flight:

Put simply IF does not start P3D or FSX - in fact that is done purely by Windows itself!

IF provides the Windows shell with the "Open with..." command and the name of your flight file .fxml - it is the same as clicking on a flight saved .fxml and choose "Open with..." P3D or FSX, whichever we are doing.

So let us say our flight fails to load:

That is saying that the saved flight can't load. I would look at the system configuration so that it can load saved flights from the desktop when the sim is not already running - this is a required function and if an addon aircraft can't accomplish this when all other aircraft do actually work - then we must look at the plane - and possibly also the scenery can cause issues - or many other things. So we can't simply assume the plane has a fault.

If we start with IF (a professional test harness) - and we get problems, we have in fact just found a problem in our system! By using IF we test the sim out from the load .fxml straight off the bat - this is a very good test of the setup. Most problems show up here.

Your problem:

Did you try stock scenery and plane and that worked? - or is that not working?

If you have got the latest version installed (see the download page) that takes care of a few indifferences with naming some items as the P3D versions have altered very slightly with each improvement, then IF has made some changes along the way too.

So first be sure to install the latest build, then test out on your stock plane and system and take it from there.

There's always a possibility that some new aircraft may respond in a different way than expected. Although I have not had any reports of that kind of thing for a couple of years, if any are reported I can usually work out the problem right away and make whatever work-around or fix required - be aware that not all planes include the proper machine readable data in the proper manner and might be reported with a slightly different name in the menu - some iflys and another major aircraft addon naming conventions were adjusted to be the correct way in the cfg a few years ago after being reported by IF, these showed differently in the IF menu system but are correct now.

That was not a change to IF, the IF menu system shows the proper name, and if not it is warning us of possible problems in the cfg and is handy when making new planes and cfg's.

There's also some other test procedures available in the front page popup menu: Terrain startup, Load Default Flight and Simulator reset in "Simulator Startup Behaviour" these are expert functions. With some planes we might use one of those settings to overcome issues of startup.

So can you tell me: I'll need to know more about what you are doing exactly if I am to help you diagnose your system. Have you tried a simple flight first to familiarise yourself with IF and take little steps, or have you set up many settings before checking anything? Don't go in and set up any kind of thing until you are familiar with the function, for example don't use Auto-scenery if you are unsure how that works.

Remember IF does nothing other than press buttons to start your sim and monitor it from data sent occasionally from the sim via simconnect - the data size is less than the size of a network packet header and has no effect on sim performance.

Also IF uses simconnect to restart and save the flights and many other functions. If the simconnect server is hung or manipulated incorrectly by another app - this will stop things working like saved flights - then again we must look at the system. IF is the test software, an ohmmeter, if you will. If our 1k resistor is showing 10k we don't throw out the ohmmeter, we get another resistor - if you see what I mean.

software architect at codelegend.com
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i9-9900X 64GB RTX2080ti 2TB M.2, i7-3960X 32GB GTX680 4TB RAID10,
Steve Waite
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Joined: Wed Jun 29, 2011 12:02 am

Re: IF Weather

Postby Steve Waite » Sun Oct 07, 2018 11:54 pm

...regarding the AI traffic. This is pure ATC traffic. The planes you select might not work - don't just select every plane and as many as possible and hope! Instead add 10, go to an airport with ATC parking locations and try again. Remember that with FSX and P3D they won't allow more planes than can be handled in this way, and only half the parking places can be populated.

I would uncheck all those planes until I know they work. Go to an airport I know has enough spaces, choose a plane I want to try or set it as Ai Buddy and see if it works. If it does I can use that.

IF is intended to add in planes around your schedule rather than replace the P3D traffic - although we can ignore P3D traffic and use only IF traffic.
software architect at codelegend.com
equipment: i9-9980Xe 64GB 2xRTX2080ti NVLink 2TB M.2,
i9-9900X 64GB RTX2080ti 2TB M.2, i7-3960X 32GB GTX680 4TB RAID10,
Steve Waite
Posts: 4513
Joined: Wed Jun 29, 2011 12:02 am

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