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This post is going to be a bit of a brain dump: I will explain where the various new types of data go for the new airports and ATC system.

First: everything lives in scenery packs.  Since X-Plane 9, every bit of scenery X-Plane has (including the default airports, global scenery, and art assets for taxiways) all live in scenery packs.  Those scenery packs live in Custom Scenery (if installed by  user) or Resources/default scenery (if installed with the sim).  The global scenery packs have their own folder in the main X-Plane folder so you can find them easily – at 78 GB it’s likely you might need to delete some, then reinstall later.

A scenery pack in version 9 can contain the following “stuff”:

  • DSFs – that is, scenery tiles for 1×1 degree areas of the world.  Those DSFs can contain a base mesh or just overlay 3-d on top of another base mesh.
  • Art assets (.obj, .fac, .png, etc.) in any sub folders desired.
  • apt.dat – an apt.dat file can provide replacement airport layouts on a per-airport basis.  You can replace one or all of the airports.
  • library.txt – a scenery pack can publish its art assets to the library for use by other scenery packs.

In X-Plane 9 we ship a scenery pack with most of our airport art assets (published to the library) and we ship another scenery pack containing Robin’s latest data – we try to update this scenery pack in each patch to match Robin’s latest.

In X-Plane 10, scenery packs are still the way you get your data into the sim.  In fact, all ATC data sits inside a scenery pack too.  We figure that you might want to make a custom airport with custom ATC, custom airport layout, and custom buildings.  So rather than reinvent the wheel, ATC data is part of scenery data.  The ATC data shows up in a few places:

  • Airport ground operations data actually live in the apt.dat file.  This includes “flow” information (e.g. which runways are in use, what’s the pattern runway) for various operations as well as the ground taxiway layout.  The ground taxiway layout specifies a connected line graph of where airplanes can taxi.  (Note that there is only one taxi layout even if there are multiple flows.  This is because even if the runway in use changes, the concrete doesn’t move.)
  • Airport controller and airspace specifications (including tower controllers) live in a new atc.dat file – you can put one in each scenery pack, not unlike the apt.dat file.
  • Voice packs are created using a .voc file and a pile of sound files.  Like OBJs, they can be put into the library – voice packs are the “art assets” of ATC.

Why is it that the ground layout is in the apt.dat file but the controllers are not?  Robin collects the apt.dat file, and we wanted to make sure that if someone moves the pavement, that person moves the taxi layout too.  Having them in separate files would be a recipe for a loss of synchronization.

Note that there is no mention of airport buildings in any of this.  Airport building locations will ship as DSF overlays – they’re a scenery pack just like we have in version 9. The default art assets made by Tom will also live in a scenery pack and be exported to the library for anyone to use.

Since everything is implemented via scenery packs, you can create anything we can create, and you can publish your work directly  via a custom scenery pack.  You don’t have to share your data with any of the central collection-and-databasing efforts to use this new technology.

There will be two types of scenery packs that ship with X-Plane (and are updated via free patches during the lifetime of the sim).

First, we have default art assets that we provide to make the sim work and to help you create scenery.

  • Default airport elements, including the airport building lego brick library.
  • Default ATC voice packs.

Then we have scenery packs that come from collected data.  We ship the latest updates.

  • Default airport file from Robin, containing airport pavement layouts, gate positions, and (in v10) taxiway diagrams and runway flow information.
  • Default airport building placements (in DSF form).  We will start this file off but then it will become something that everyone can contribute to and use.
  • Default ATC controller file, containing airspace information and controllers/frequencies.  We will seed this file with center controllers to cover a big chunk of the world, but I am hoping that we can accept user-submitted corrections and contributions.

(If you squint at this list, you’ll see the divide: we are trying to involve the entire community in data-gathering activities, but we are having our internal art team make the default art assets.)

Finally, there is one more piece to the puzzle: autogen.  Autogen is a horribly ambiguous world in flight simulation because it means 85 different things.  So let’s be more specific: automatic in-sim generation of data.  When the sim is missing data, what data will X-Plane “make up” on the fly?  There are two cases of automatic data generation in the sim while you fly in version 10:

  1. If there is no controller specified in any scenery pack for a given airport, but there is a tower/ground/delivery frequency for the airport, Chris’s ATC engine will automatically create a controller based on the frequency.  This means you get tower/ground/delivery ATC on the right frequencies for all of the towered airports, even if we don’t put those controllers in the default controller file.
  2. If there is no airport layout for a towered airport, we will generate a taxi layout and default flows by picking runways and analyzing the taxiway structure.  This allows you to have AI ATC at any towered airport.  (The layouts that X-Plane generates are not going to be as good as what you can build in WED.)

We almost always prefer pre-generation of data to in-sim generation – it lets us use a higher quality algorithm without hurting fps.  (One of the limits of the ATC layout generation algoirthm is that it can’t use too much memory since it is running inside X-Plane.)  But in the case of airport controllers and layouts, a custom scenery pack can contain an airport that we’ve never seen before – so we have to be able to generate the matched ATC data on the fly.

About Ben Supnik

Ben is a software engineer who works on X-Plane; he spends most of his days drinking coffee and swearing at the computer -- sometimes at the same time.

26 comments on “ATC And Airports – Where Does All of the Data Go?”

  1. The ATC secret unveiled! 🙂
    Seems reasonable, scalable and functional and I love the community data-gathering idea. Good job!

  2. Ben, all very interesting stuff. Looks like XP10 is going to seem a lot more “alive,” as opposed to post-apocalyptic.

    How are the ATC voice files generated? Will that be a user-contributable feature too?

      1. I don’t think that’s accurate. Voices come in packs. You can add your own voices using the library system, and a group of people can start a repository of voices like OpenScenery X.

        But we are not planning on having a _formal_ system to contribute voices, just like we don’t formally accept airplanes or building OBJs.

        Basically the only thing we “collect” right now is airport data, and in the future the only thing we will continue to “collect” is _data_.

        LR has in the past used a variety of contributed art assets – always on an ad hoc individual basis. I have no doubt that at some not in LR’s full-time employment point someone will make a voice pack that we end up using. But that will happen when it happens on a one-off basis.

        Does that distinction make any sense?

      2. And hey, have you yet determined standard dimensions for different airspaces in case no ATC pack is installed?

        1. hmmm, if no ATC pack installed, this worries be/ makes me confused. So excited over new features and ATC, load up a US city for example and airport- bam you have atc. Chicago center, Boston center, etc.. Once again, like scenery at an airport not installed or made by user, will ATC be non existent unless made or downloaded for a given area.

          basically to sum up all my inquiries on these new features and has me kind of going ehh on v-10 in a way is that- How user friendly, realistic and functional full sim will be shipped on DVD default/ given in patches and on the .org soon? Like I’m picturing getting it, new planes look nice, weather, some atc etc. I go load ORD or LAX and get empty plain tarmac boring airport and no ATC with directions clearly stating where we are, unless I either learn how to make that happen or someone else does to download it. Not cool

          1. As a loyal xp fan, whos engaged and interested in the sim, use it daily on my own and friends. former private lesson taker etc, & will buy v-10 asap upon sell date, I am bothered that my inquiries are not addressed. Simply looking for info and answers. Not too happy with seeing replies to things made after mine yet I have good questions too. Please answer.

          2. Your questions have been answered…numerous times. You just keep asking the same thing reworded in different ways and the destination is always the same…that is, asking for more screenshots and venting about how the system isn’t going to work how you imagined.

          3. Ehh, yes they have been answered but not in detail or clear cut and dry this is what well get on dvd exactlty. how many airports will or wont have realistic atc, sure new lego bricks and art but only adding them default to a few places, leaving it up to users do add more.
            what i imagined the sim ( v-10 to be) is what the forums, screen shots and xplane.com news pages have said for a darn long wait that isn’t over. I pictured really nice new scenery, no more crappy photo terrain of walmarts all over, finally airports with terminals and such ( at least for major ones) ATC centers etc.. but now, unless i’m wrong, its looking like while still those are true, limitations on what we will get on dvd were not addressed originally. aka v-10 feels like a new sweet sim with many new features, yet shipping with all the tools for us do to on our own + add on vs buying a ready to go sim where you can load a major airport, see new art assets, realisitic atc citing where you are and such by default.

          4. Not trying to burn ya guys or be mad, it’s a sim, a game. However really want to see clear cut info on what exactly we will get/ not be getting on dvd. how many features are ready to use out of the box for users like me who dont make scenery, atc, etc or care. Put dvd in, load and fly.. end of story minus some downloads.

            screenshot wise, yeah I’m persistent, so are many fans anxious. weeks and months on end with little to no news or shots is annoying. and no a screen shot of a messed up road curve or light counts. Vids like the 747 and neighbor hood from JANUARY count. world scenery, weather, more planes. v-10 tuesdays easy to do. just want the darn sim now

          5. Hi Chris, this is not the forum for these types of questions/requests. Yes we tend to discuss some of the features that you’ll see on the horizon but the main purpose of this Developer’s Blog is for Ben and I to disseminate information to our developer community about the inner workings of systems and sub-systems that they may need to be aware of to continue developing for X-Plane. For the marketing-type questions that you have, you’ll have to wait until product release when things are more concrete.

          6. Right – part of the point of the developer blog is to share development information with third party authors – to give them situational awareness. It’s a lot better for everyone if third party devs have some idea of where they’re going – otherwise the only thing they can do is “stop everything and wait”. If we have preferences for certain routes in the future scenery system (e.g. moving toward GPU effects for lighting or continuing to use the library) this helps give authors a road map. We want third party developers to know that their investment in 3-d modeling and texturing is still useful in a v10 world.

            But this is all development information. It doesn’t answer the question “will you be happy when you get your DVDs.” That’s not something for this blog.

          7. Alright , Chris thanks. Hopefully I will get some answer before Christmas, let alone 2012 by the time it actually ships to my door..

  3. Great stuff Ben.

    I guess the next question is, what’s the plan for AI aircraft when it comes to ATC operations? 20 max? Built-in planes only?

  4. Hi Ben! Sorry for not keeping to the subject, but one thing that interests me is the current state of DEM data for the planet. When XP8 came it was like a revolution for us. At last we had highly detailed mountains with very good detail when it comes to hight data. This in turn I remember was thanks to NASA (?) that had published very recent, global earth altitude data. I think it was collected in 2006-7? What would make XP even more realistic would of course be to implement even more exact data. This would, with even more high-res ground textures, make surroundings look more life-like.

    Would you like to give some words to us about the current state of global DEM-data? What sources are there, and are there any new data that NASA (for example) is to publish not too far from now in time? A discussion about DEM-detail and storage would of course also be very interesting to hear from you but I respect your time – so if you feel you need to focus more on XP10 right now, thats perfectly fine with me.

  5. All very interesting as always. Really looking forward to seeing all this in action and getting the iCrayons out to complete airport traffic flows.

    I note that it appears that custom .atc files will be allowed in custom scenery packs. I am a bit surprised by this. After all, one of the reasons we don’t have custom nav.dat files is that the navaids form a global network that shouldn’t be tampered with for localised indulgences. Is airspace layout not similar?
    And (without knowing the exact level of detail that is possible in describing the controlspace around an airport), whether held in a central repository or across multiple packs, is there not also potential here for conflicting data to be presented to the sim for two close airports in two seperate packs. How is that resolved?

    1. Hi Cormac,
      ATC data can include custom voice packs, and potentially custom controller profiles that are tied to that custom voice pack. In other words, you can go replace the KBOS final controller with a custom definition that always uses your own audio recordings of…the real KBOS final controller. So the lines between custom scenery and data are blurry.

      Also, note that one of the main reasons why the navaid file isn’t user-replaceable is that there isn’t a good “identity” to replace. A VOR isn’t uniquely identified by any one thing, so when you say, “replace this VOR” we don’t REALLY know which one you mean. ATC sectors use a system-wide ID, at least I think. (It’s been a while since I looked at the controller DB code.)

      Air space can be defined subtractively, so if center’s airspace is defined to include “everything BUT the underlying faciliites in this area”, replacement of an approach controller with a new definition with an edited sector size will simply edit the cutout of the overlying controller. Or something like that. Again, it’s been a long time…

  6. speaking of ATC & Airports, will the scenery at select given airports be really realistic in terms of how it “looks” including terrain textures and images. Unlike the current v-9 textures with baseball fields, walmart and ikea ALL OVER THE PLACE, which is really annoying, how will v-10 be looking. when can we see screen shots of global textures?

    second- since one of you said most airports will still be empty 🙁 aka not realistic, if theres no scenery package to download, and obviously theres too many for you guys to do on your own. how easy will it be for users like me who don’t use WED, make scenery code, etc to simply load a airport, select a “lego bring obj” and place it?

    1. You really should look into the posts related to the use of OSM data to get an idea on how this will change……

  7. I recently finished a major “VRC” re-write of Singapore Changi airport using Google Earth as the coordinate source for ATC use. This would not really be completely helpful in the Scenery sense but has all the runways, holding points, taxiways, gates, Tower etc recorded to as close as humanly possible lifting coordinates off Google and inserting them into a VRC sector file.

    I can send a picture if you like and you can asses whether this would be helpful.

    1. Hi Ken,
      I’m afraid we don’t have time to look at any specific new data before we ship. But this does bring up an interesting idea: conversion between VATSIM-client sector files and X-Plane ATC data. Is there a UI tool for editing sector files, or did you build the file by hand?

  9. I’d like to ask you one thing about ATC: if you include any type of autotune, please add an option to disable it as well, please!
    I know a lot of people (me included) who find this feature very very annoying and unrealistic.

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