AVSIM Freeware Preview

Advanced Simulated Radar Client

Product Guide
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ASRC, centered over Amsterdam
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Mike Evans, David Hendleman
An outstanding new ATC Client for the VATSIM network
D/L Size:
Self-Extracting Installer
Win 98, ME, 2000, XP
Previewed by:
Chuck Boudreaux, AVSIM Managing Editor
Matt Johnson, AVSIM Technology Specialist
Dalibor Jovanovic, Contributing Reviewer
Miro Majcen, AVSIM Managing Editor
Mark Roberts, AVSIM Library Manager
Rick Rossner, AVSIM Senior Library Manager


The growing popularity of the various online ATC networks has surprised many over the past few years. It all started out with SquawkBox — a simple pilot client that has integrated with Microsoft's Flight Simulators since version 6, and ProController, a standalone controller client providing a radarscope and a method to talk to other controllers and pilots.

While SquawkBox has been continually developed for MSFS, and also ported to many other flight simulators — Aerowinx PS1 and Fly! to name but two — ProController has remained the only Windows controller client. MacRadarScope, a new controller client for the Mac, was released recently, but controllers using Windows have been increasingly becoming desperate for an updated client with increased stability, realism and features.

Now, at last, the wait is over. The Advanced Simulated Radar Client (ASRC) is the Second Generation Controller Client for the Windows platform, and is due to be released imminently.

ProController's source code has never been made available — not even to other developers involved with the network protocol -- meaning that any new client would have to be developed from scratch. Around a year ago, Mike Evans and David Hendleman took up this challenge, and began coding a replacement for the aging client.

Since ProController was written, we have moved into a world where available hardware and software technologies allow a functional representation of the true controller environment on a home PC. ASRC makes full use of that new power to deliver a product that provides a truly immersive environment:

The seamless integration of voice and text;
The coast mode predictive technology which keeps the aircraft moving on the screen during a lag drop or quick reconnect,
Expansion of the radar, in essence, across the entire screen...
These are just a couple of the innovations that pull you into the reality of the experience.

Installation and Configuration

Installation of ASRC is simple. The software is supplied as a self-extracting installer, which will update your Windows Installer version if required, and then install ASRC using that. The installation process is identical to most installations, with no particular issues to report.

During the beta phase, ASRC has been shipped using a key system. This key is read by ASRC during the startup procedure, and sets the controller's real name and informs ASRC to which networks it may connect. It has not yet been decided whether ASRC will continue to use keys after release, but the developers have retained it as a possibility. The key installation requires downloading a file from a website, and placing it manually into the ASRC directory.

Configuration takes place in two main areas: in the Settings dialog accessed from the top menu bar, and also on the scope itself using the simulated ARTS-III/DSR interface.

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The Settings dialog is much simpler than that of ProController, and controls the "simulation-based" elements of ASRC.
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The configuration of the radarscope takes place on the scope itself. Note that all the overlaid elements are transparent, providing maximal "real estate" for viewing the radar.

Most of the "simulation only" features (that is, features necessary for ASRC to function) are handled by the Settings dialog, pictured. Here, you can set your ATIS, change the keystrokes used for selecting aircraft and controllers, the sensitivity of the "snitch patch" or conflict alert system, and various other ASRC core functionality. You will notice that voice configuration also takes place here – more on which later.

Scope display configuration now takes place on the scope itself. The DC (Display Configuration) element is displayed by default in the top left of the radar, but can be "rolled up" and dragged about to wherever you might prefer. Most of the scope configuration is similar to that of ProController, allowing you to change colors, lengths of some guides, and the speed at which multi-value data blocks will rotate.

The Radarscope

As in all ATC-based software, the radarscope is probably the most important element of all! As already alluded to, the developers have done their utmost to ensure that the greatest amount of radar space is made available at any time, making everything that appears over the radar translucent.

A new feature with ASRC is that the radar scope deliberately emulates real-world scopes. ASRC's first release will ship with emulations for DSR and ARTS-III — the American Center and Approach/TRACON styles of scope respectively; v2.00 is expected to include full EuroControl emulation in addition to those listed above.

This "emulation" also falls pretty close to the mark, but inherently adds to the learning curve required. No longer are there only four or five different aircraft states as there were in ProController — now there are around fifteen states on each radar type! This is certainly rather unnerving, but the new states rapidly start to make sense, and indeed make controlling easier, once you have figured out exactly what each of the states mean!

ASRC will also look at aircraft comments for certain special strings (/V/, /T/ and /R/) and flag the appropriate as voice-capable, text-only, or voice-receive-only on the scope by changing the aircraft number to "N6034T/v". If the pilot neglects to add one of the "magic" strings, the controller can also manually tag an aircraft into one of these states.

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A scope centered on Memphis International, while online. Notice the translucent chat box near the bottom.
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A scope centered on Cleveland Hopkins, while offline. This shows some brighter colors and also some STARs for KCLE being superimposed on the scope.

Several features are overlaid onto the scope—all of which can be rolled up so that simply their title is displayed, making more room for other information. The first, the Display Configuration (DC), has already been mentioned in the Configuration section above.

In the top right (by default; all of these elements can be relocated to wherever you like on the scope), is the Controller List (CL). No longer will you need to go to the "Who's Online" entry in the File menu, or call up the old right-click Handoff menu to find out which other controllers are nearby! The CL is tristate: "B" (for Both) mode displays everyone connected that is within your visibility range; "A" (for Active) displays only active controllers in a valid position, and "O" (for Observers) shows only observers. This list of controllers also provides a useful "one-glance" monitor for several states, such as whether they are currently calling you on voice, waiting for a text message to be answered, or whether you are text-messaging them.

In the bottom right is the Computer Readout Display (CRD), which contains the Response Area and Message Composition. This contains details of weather at airports the controller has decided to track, responses to scope commands (i.e. abbreviated flight plans, squawk code assignations) and error messages.

At the bottom of the screen is the radio interface, which is now completely transparent. This is both useful since it allows you to see the radar through the radio chatter, but can also be a pain, given that with no background, occasionally the radio messages become unreadable due to the radar indications underneath. The developers could consider a translucent background similar to that used by the text-chat box, which might help in alleviating the problem.

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A scope centered on London Heathrow, showing the full flight strip for KLM1007, and BAW463's abbreviated flight strip in the RA.
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A scope centered near Vienna showing airways, a very well-staffed airspace (look at the CL), and some flight details.

The ASRC command set is much richer than that in ProController. Major additions include being able to create and modify flight plans directly, use a "scratchpad" per aircraft to send codes between controllers, "point out" an aircraft (i.e. make its tag appear in full) on another controller's scope, and much more. Transponder codes also take on a new importance: ASRC manages aircraft tagging via transponder codes now, unlike ProController which didn't much care what squawk you gave to an aircraft. This adds a new layer of realism to controlling, and in fact helps procedure—and points out the few pilots that don't listen carefully enough to their squawk allocations!

Other useful features are the addition of five "lists" – departure, arrival, coast, request and hold. The first two are self-explanatory: they can be used to list aircraft arriving and departing from your controlled airports. ASRC can either add aircraft to these automatically based on their flightplan (see the right hand side of the Settings dialog), or they can be added manually via a command. The request and hold lists are manually maintained, and allow you to list those aircraft who have made a request you have not actioned yet (i.e. a call for clearance responded to with "standby"), or those aircraft in a hold. No more embarrassing "oops, forgot about you" moments for controllers, at last!

The Coast list shows all aircraft in coast mode: a new feature to ASRC. In ProController, if an aircraft lagged off the network, it would remain as a stationary radar blip, which was not particularly useful. In ASRC, the course and speed of the aircraft is maintained, and the aircraft "coasts" along its current flight path until a new position update is received over the network; or, if the aircraft has been gone a while, the controller "drops the track".

Furthermore, the alias system has been given an overhaul. At last, aliases can be strung together, and they have also gained intelligence. For example, you can create an alias called '.destalt' with the string '$1, altimeter at your destination is $altim($arr)'. Then, if you invoke it via '.destalt KLM1010' (who happens to be flying into Amsterdam), ASRC will generate the radio message 'KLM1010, altimeter at your destination is 29.95'. The manual details a significant list of new "alias macros" —and I can indeed expect that these will be well-used by controllers.


One of the most impressive—and what AVSIM believes will probably be one of the least foreseen—improvements is the near-complete integration of Roger Wilco (RW), the voice program of choice for VATSIM use, with the new client. Having started ASRC, all interface with RW takes place from within the ASRC client via the Voice Switching and Control System (VSCS).

Once the appropriate option is set in the Settings dialog, ASRC will start RW of its own accord, and enable it to monitor and transmit on several channels at the same time—a major improvement from the normal RW client. The new interface allows controllers to monitor other controllers in addition to their aircraft control channels, and to easily switch channels on the fly: up to 24 Air to Ground channels can be set up as "push-buttons" on the VSCS. Furthermore, a controller can transmit, receive, or do both on as many channels as he wishes simultaneously; however, this will obviously be limited by available bandwidth.

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A VSCS Air-to-Ground page, set up for use in Memphis Center.
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A VSCS Ground-to-Ground page, set up for use in Cleveland Center, also showing how the VSCS overlays the radar during use.

The screenshot shows one of our previewers' setups, for use in Memphis. Importantly, you won't need to memorize all the frequencies and type them in every time you want to switch channel any more. In the screenshot, 125.80 is selected as the primary channel and 133.65 is being monitored, with the green blocks showing what features are active.

Also, ASRC's integration with RW allows intercom, monitor and override facilities between controllers. A long-awaited wish from controllers has been answered: handoffs and controller coordination can finally take place using voice! A similar pushbutton system exists for "Ground to Ground" channels, based on a Position File that maps controller callsigns to radio callsigns and frequencies.

The RW integration appears strange at first sight due to the way ASRC performs its multi-channel trickery. The reason for this is that ASRC actually implements a local "proxy" for Roger Wilco, which affects the location to which Roger Wilco connects. You'll find that your Roger Wilco is connected to the "localhost" address ( as opposed to the actual voice server, and that you will only see yourself and "ASRC" in your voice room. ASRC takes care of the onward connection between yourself and the actual voice server, and the servers of other controllers. Firewall users take note: you will need to open up an extra port on your system as detailed in the documentation for the ASRC/RW integration features to work properly.

As well as the voice features, the VSCS manages "text" frequencies too—it truly is an integrated communications center for the entire client. Clicking an "Air to Ground" push-button will not only set voice channels, but will also configure text radio channels too.

Overall, ASRC provides a single, unified method of handling communication in the form of the VSCS. Obviously, the problem of the two media (text and voice) is one that has been foisted upon the program by the necessities of the simulation environment—real ATCO's don't type at each other, and nor do they type at aircraft—but ASRC contains an elegant and transparent solution to this thorny problem while maintaining a high degree of realism.

The Transition from ProController to ASRC

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The old ProController client, centered on Cleveland.
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ASRC centered on Cleveland at the same zoom level with the same traffic. Notice how much more visible radar there is!

ASRC truly is a revolutionary development as far as the controller client is concerned, as opposed to merely an "enhanced ProController". Comparing the two user interfaces, almost the sole commonality between them is the radarscope! While this change will undoubtedly prove confusing to ProController veterans, ASRC allows all the other functions to be overlaid on the scope, allowing for a much cleaner look and far fewer focus-changes between windows. The authors explain, "ASRC is a reality-based controller client. In designing ASRC, we have gone to great lengths to create an interface that enables the simulated controller to manage traffic in as realistic a way as possible."

It really is impossible to itemize the operational differences between ProController and ASRC, because ASRC really is a fundamentally different product. ProController was the best simulation of real-time, real-life controlling the designers could create when it was developed, but hardware and software limitations precluded a true representation of what actual controllers used then or today.

Our previewers, some of whom are experienced VATSIM controllers well-versed in ProController usage, found that the learning curve for ASRC is rather steep, and all agreed that ASRC is certainly rather intimidating at first glance! ASRC works very differently to ProController in many respects—many command names have changed; processes which were unimportant in ProController now become extremely important in ASRC; and, of course, the entire interface has changed, meaning a new set of mouse movements, clicks and key bindings to learn. Reading the manual provided will prove extremely important (not to mention useful) – and we will go into some depth about the documentation later in this preview.

The big concern among current ProController users will no doubt be: "If this is a new product, built from the ground up, how hard is it to learn?" Indeed, our previewers had those same thoughts; however, our concerns were allayed when we found that this is one of the most intuitive products we have used in some time. While it is a new product, it was also built by users—Mike and David are both experienced VATSIM controllers. As a result, ASRC is an intricate blend between a brand new product, and the legacy interfacing needed to allow a smooth transition from ProController.

However, this certainly does not mean you will be able to boot it up the first day and be working SoCal Approach during a massive fly-in! You will need to start out with limited traffic while you pick up the flow and increased functionality ASRC has to offer. Chuck Boudreaux, one of our preview team, shares his observations:

"I found I could handle traffic comfortably within about three hours of online work with ASRC. By the time I had spent 10 hours between controlling, observing and playing around off-line, I was comfortable with the basics. But even now, after another week of working with the product, I continue to learn, mostly because this product offers so much more than we have become used to in ProController."

From the general experience of the preview team, we feel that the majority of experienced controllers will be at more-or-less the same level of controlling they were capable of in ProController by the time they have around 12 hours of ASRC experience—however, learning all the new features, which often prove to save time reduce workload, will probably be a continuous exercise for quite some time.

Backwards Compatibility

ASRC uses the same network infrastructure as the ProController client, and as such ASRC can be considered to be "backward compatible" with ProController. The methods that may be used to perform a given action may have changed, but all the actions that users of ProController need for controlling are fully implemented in ASRC, and are protocol-compatible. In essence, a controller does not need to worry whether other controllers in his area are using the same client as him or her; the clients and network will "do the right thing".

For example, this means that a handoff in ProController will be rendered as a handoff in ASRC, and vice versa. Some functions aren't implemented on ProController (for example, the "pointout" assistant, and arrival and departure lists)—however ASRC shows clearly which other local controllers are using ASRC, and which are using ProController, so the controller can be aware of the capabilities of the other client involved in the transaction.

ASRC's flight plan amendment facilities, and assignation of new cruise altitudes, are implemented on the server-side, and these changes will be reflected to ProController users. While ProController users will not be able to make these changes themselves, they will be able to see changes made by ASRC users.

Sector files—the data which specifies how the radar scope should be displayed—have remained in the same format as those used with ProController. However ASRC interprets them much more strictly according to the published specification, while ProController was rather lax in its insistence for sector files to follow the rules. Some vACCs and ARTCCs may have early teething troubles when they find that their long-established sector files do not function as expected in ASRC; the vast majority of these problems will be easily fixed and as such will not prove an impediment for transition to the new client.

Documentation and General Comments

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A section of the Configuration documentation, discussing the DC.
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A section of the Usage documentation, discussing DSR tags.

ASRC's documentation is a weighty tome – over 700KB of documentation is shipped with the software in HTML format, which is roughly equivalent to 45 A4 pages. The manual is split into four sections: Introduction, Configuration, Usage and Reference; and a Quick Reference section is also provided.

The Introduction is less an introduction to what ASRC is, but, rather, why and how ASRC is like it is. Admittedly, while the information currently in the Introduction is useful for reviewers and developers, it may only be of limited use and interest to the general "controlling public".

The Configuration section covers all of the available configuration elements in ASRC. While it certainly explains the function of each setting, some of the general descriptions on the periphery of the software-user interface were lacking. For example, there is an explanation of how to set up a Position File, but nothing to say what a Position File means to the user and how it is used. For what it's worth, a Position File declares which controllers operate near you and how those controllers' actions are rendered on your scope, and how those controllers should be contacted. That said, the section is more than adequate in its aim of explaining to users how to configure ASRC to their liking.

"Usage" was fairly easy to understand and follow. The learning curve for understanding all the many different symbols used in the DSR and ARTS modes was rather steep and took a while to get used to, but after using the program for a while, figuring out what the different codes mean and in what mode they are found becomes second nature.

At the time of preview, the Reference section is rather thin, and only details commands useful for supervisors on the VATSIM network. We feel perhaps this section is rather a misnomer.

The Quick Reference Card certainly serves its desired purpose, but there is a lack of distinction between elements of the command to be typed literally, and those that are "placeholders" for codes that should be substituted from the controller's current environment.

The manual could certainly benefit from short explanations of the more unfamiliar terms relating to the scope and command set, and possibly some "common situation" tutorials in order to assist in the application of the reference material. However, bearing in mind that the manual, along with the software, is a "work in progress", we hope that these issues will be ironed out by the time the full release occurs.

Occasionally, our preview team felt that the developers' attempts to remain realistic sacrificed product usability. Quite a few of the team found difficulties in setting the radar scope up to have readable content due to there not only being a color choice, but also a set of "master brightness" controls which override the intensity of those colors.

An ATCO's View

As part of this preview, we asked occasional AVSIM contributor Dalibor Jovanovic, a real life ATCO in Slovenia, to examine ASRC and to compare it with the systems he uses on a day-to-day basis. Here are his views.

"Air Traffic Simulators are often very costly - almost always over $100,000. They are fairly complicated programs, which must provide not only realistic output on the controller's side, but also must contain easy-to-use editors for exercises, maps and aircraft. Since their main goal is to enable realistic training, live pilots are needed to guide the aircraft, who are called "simpilots", or sometimes simply "drivers". Usually there are two such pilots per one ATC trainee, whereby each pilot commands half of all the aircraft in the exercise. What they see on the screen is similar to what the ATCO sees on his - a bunch of radar targets with labels. The main difference is that drivers can control the airplanes directly, by obeying the orders from the ATCO trainee.

"ASRC is not a training tool, but rather a meeting point for virtual ATCOs and pilots, who want a more-or-less realistic service to give a new dimension to their online flying. The use of the VATSIM network and ASRC / SquawkBox software easily meets this demand!

"At first glance, ASRC looks like some of the professional training software I've seen in my career. The menus are nicely integrated into the HMI (Human-Machine Interface). The main buttons open sub-buttons in the radar window, but since they are transparent, they don't obscure the view to the radar screen. The chat window and command line are at the bottom, and they are also perfectly integrated into the background. All the colors can be changed, but virtual ATCOs might want to bear in mind that the FAA and EuroControl recommends a maximum of 5 colors be in use on a scope at one time, to avoid information overload. The most recommended color for background is dark grey, since it provides the best contrast, and the usage of red is strictly reserved for danger or failure of equipment. Radar symbols (aircraft) are usually black, white or green.

"The radar symbols and labels are very realistic - I have just two observations. Compared to usual European scopes, the position of the current level figure is wrong - it is on the far right when it should be on the far left. I had big problems when I controlled online, because I was instructing them all the time to descend or climb, but they claimed that they already complied with my command. The reason was that I was looking at the figure, which shows assigned flight level, as I'm used to in real life. In addition, the assigned level should be in a different color if it is different from current level, warning the controller that he or she has to do something with that flight.

"The other remark goes to the label manipulation - most scopes implement this using the right mouse button, which is assigned to scrolling the map. One can move the label only by typing a command, which is very time consuming during heavy workload periods (for instance, in fly-ins). Instead, side-sliders could be used to scroll of the map. However, these are certainly all nitpicks!

"Otherwise, I found no serious flaws. Given my experience with the real-life scope, the transition to ASRC is simple (I learned it in 15 minutes) and offers a lot of enjoyment to both pilots and controllers. When there are 50+ planes per hour of course, the sweat certainly starts to pour! It may seem easy to some, but keeping fast moving planes at least 5nm or 1000ft apart is not an easy job, especially if weather deteriorates and everybody is avoiding cloud build-ups!"

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A tower-style view of London Heathrow.
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A center view of London ARTCC, also showing the British coastline.


In closing, we asked each of our preview team for a short summary of their feelings about ASRC.

Chuck Boudreaux, AVSIM Managing Editor, from Berwick, Louisiana: "When I downloaded ASRC, I had some preconceptions or ideas about what I hoped it would be. What I found shocked me. This was not the evolution of ProController, but a new, powerful controller client. After a solid week of working with the continually evolving program, I can say it has everything I wished for, and many things I could not even have imagined!"

Matt Johnson, AVSIM Technology Specialist, from London, England: "ASRC is an impressive piece of software, without a shadow of a doubt. The technical accomplishments made thus far—the integration of Roger Wilco, the realistic simulation of the DSR and ARTS-III interfaces, are great achievements. Furthermore, even though the program is not yet in a finished state, it is remarkably stable and relatively well-polished—a testament to Mike and David's fine skills. I look forward to seeing the public reaction towards ASRC!"

Dalibor Jovanovic, AVSIM Contributing Reviewer, Real-life Controller, from Ljubljana, Slovenia: "The guys behind the Advanced Simulated Radar Client have done a great job creating a very usable tool for controlling on-line flights. I have nothing but respect for them!"

Miro Majcen, AVSIM Managing Editor, Real-life Paraglider Pilot, from Ljubljana, Slovenia: "ASRC brings fresh content into the virtual ATC world. From the features you can see, like the brand new menu system for selecting various options of the visual display, to those you can't see but will help you guide the airplanes safely and with ease – the ability to monitor multiple frequencies at the same time – Roger Wilco integration – interaction possibilities for communication with other ATC – the ability to modify flight plans – macro integration and more. ASRC will surely bring more interest from ordinary pilots who would like to start controlling. Bearing in mind that the product was still in heavy development at the time of writing this preview, it clearly shows a leap in the way virtual ATC controllers will work from now on and hopefully that means even more traffic, especially in areas where traffic is also dense in real life but are still waiting for the boost up in this virtual world."

Mark Roberts, AVSIM Library Manager, from Fort Irwin, California: "In summary, I think ASRC is truly a remarkable accomplishment that will change the way you control. It will attract many new controllers and this VATSIM desperately needs. It still amazes me the amount of time and energy that people spend making our hobby better—not to mention the fact that this is done for free! In how many other hobbies can you find the talent and add-ons we have available to us? Thanks again Mike and David."

Rick Rossner, AVSIM Senior Library Manager, Real-life Pilot, from Three Rivers, California: "I feel that the overall functionality of the software is very impressive, and while the overall learning curve is very steep to start with, it does get much easier to understand after playing and experimenting with the features and benefits. It's also very clear that a great deal of planning and thought has gone into the development of this program, and I am sure it will be very well received."


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The preview above is a subjective assessment of the work of the authors. We disclose that Matt Johnson is a member of the SimClients / ProtoDev group of developers for VATSIM network software, the same group of which Mike Evans and David Hendleman are members. All other members of this preview team have no connection with the product authors, and this preview has been edited by a member of the AVSIM Editorial Board before publication. We feel this review is unbiased and truly reflects the performance of the product in the simming environment. This disclosure is posted here in order to provide you with background information on the previewers and connections that may exist between them and the contributing party.

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