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ACSim and TWRTrainer Instabilities


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This has been brought up in the forums a year or two ago, but I'm going to start it up for the purpose of finding some much needed solutions.

 

As computer technology continues to develop, I am having an increasing number of problems running both TWRTrainer and ACSim for training sessions with students. These problems range from minor "oh, that doesn't work right now" to major "umm, we can't do the session tonight, sorry" malfunctions. I'm continually experiencing random breakdowns of ACSim, issues opening TWRTrainer, and an increasing number of training staff members that say one or the other programs is not working for them.

 

Below this thread is one that mentions an error I keep receiving in ACSim after opening a sector file. It's an "unknown error." This computer (a fairly new Dell) refuses to run the program, and one of my instructors e-mailed me today to let me know that his computer (a brand new Dell) does not run ACSim.

 

TWRTrainer, with all due respects to developers and the amount of time it took to build and code, is filled with instabilities. For example, not one computer in my house (there are 4) allows me to close an airport file and reopen another without restarting the program. Like ACSim, the program will freeze up on occasion. In my own opinion, though, TWRTrainer is much better than ACSim in terms of stability and usability.

 

I really have no idea what's going on. I have a feeling, though, that both are going to need some upgrades or a total revamp as our platform technology continues to change. The two entities, the system and the software, do not seem to want to work together very much anymore.

 

With in-the-future concerns aside, does anyone have suggestions as to how I could go about correcting the problem with ACSim (it's my primary issue)? Running the program is the primary concern. I don't really care if I can't add aircraft manually without the session freezing up; it's something I can work around. Please visit this thread if you know of (or can guess at for that matter) any solutions.

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TWRTrainer, with all due respects to developers and the amount of time it took to build and code, is filled with instabilities. For example, not one computer in my house (there are 4) allows me to close an airport file and reopen another without restarting the program.

 

That is by design ... it is not an instability.

 

Like ACSim, the program will freeze up on occasion.

 

I had a problem with ACSim where after a while it would lock up, if I was running a fairly large session with a decent number of targets. I found that the number of packets being sent out and back on the network interface was causing the network driver to lock up, presumably due to I/O buffer limitations. Changing to a different network card fixed the problem right away. (I was using a NIC integrated with the motherboard, and I switched to a separate PCI NIC.)

 

This was before I developed TWRTrainer, so I'm not sure if TWRTrainer would cause the same issue, but it should have, since they both produce the same level of packet flow per target.

 

I've heard of a few other people having the same issue with both ACSim and TWRTrainer, and it has been fixed in some cases by upgrading the network driver or changing network cards. I'm not saying this is the only possible cause of lockups with the programs, but it's something to look at. If the problem is affecting multiple machines on your LAN, then it could point to a similar buffer issue with other network hardware such as routers or modems.

 

If this is the problem, unfortunately there's little that can be done about it in the software. It's a limitation of the VATSIM network protocol that requires so many TCP/IP packets to be sent back and forth for each aircraft.

 

By the way, how many targets are you running in the session when the lockups occur? And how long into the session does the lockup usually happen? Does your ATC program start to drop targets off the scope when the TWRTrainer lockup happens?

Developer: vPilot, VRC, vSTARS, vERAM, VAT-Spy

Senior Controller, Boston Virtual ARTCC

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I always get a lockup in ACSim when I manually add aircraft in situations where a .acs is also running. I don't do that anymore for that particular reason. In the simulations that I typically run (they are at our smaller LCTP facility, KCOS) I have no more than 15 aircraft in the situation. When I run situations in Denver in our D01 TRACON, there are probably 45 aircraft at a time. I have the situations set up with 8-10 aircraft in 10 mile in-trail spacings entering the TRACON from the arrival gates.

 

In TWRTrainer, I don't recall targets disappearing, but a freeze up hasn't occurred in a long time for me in TWRTrainer.

 

Thanks for the tip about the network card. Do you have any advice for getting the sector file to load in ACSim?

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I've always dreamed about making a new version of ACSIM (One that could trully do holds, or fly specific instrument procedures) and all that good jazz

 

Unfourtauntly, my code skills is severely limited to PHP/MYSQL and some C++ from many years ago. I woulden't even know where to begin lol.

 

 

-Mike

Michael D. Hodge Jr

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  • 3 years later...
By the way, how many targets are you running in the session when the lockups occur? And how long into the session does the lockup usually happen? Does your ATC program start to drop targets off the scope when the TWRTrainer lockup happens?

 

I know this is a very old post, but this still happens to our division training. Both an instructor who uses TWRTrainer and ACSim to do Sweatbox training, as well as me with the ES, experience constant severe traffic dropouts.

 

This is rather distracting, if Ross, or anyone have already found a solution to this, we'd love to hear about it. Sorry if this has been solved elsewhere, we hadn't had luck in finding it.

 

Cheers

Brendan Chen

VATPRC Tech Support

You make the difference!

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Brendan, do you only experience these dropouts when you have lots of traffic loaded up, or does it also happen when you only have a few targets?

 

I had a similar problem with ACSim way back in the day, before I wrote TWRTrainer. If I would load up about 30 targets, about 5 minutes into the session, targets would stop moving and start dropping off the screen. I eventually determined that it was likely caused by my network card getting saturated due to so many incoming and outgoing packets. (The number of packets that ACSim/TWRTrainer/ES generate grows exponentially with the number of targets, because each target sends its position to the server, and the server sends it back to each target.) At the time, I was using a cheap network card built into the motherboard. I changed to a dedicated network card from a reputable manufacturer, and the problem immediately disappeared.

 

Obviously I can't say for sure if this is the issue you're experiencing, but maybe it's something you can look into.

Developer: vPilot, VRC, vSTARS, vERAM, VAT-Spy

Senior Controller, Boston Virtual ARTCC

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Ross, surely this is not something I'd expect or ever thought of, so thank you for pointing me to this direction!

 

I'm not sure whether that was the issue, but this problem I experienced lastnight when I was testing a plugin I was building for ES. I had approximately 7 aircraft loaded.

 

The first run, all was well, and beyond that, no good. Traffic immediately dropped out, and finally I was playing around with 3 aircraft.

 

In the past, it was three aircraft coming into an airport (TMA), approximately 2 min after, another 3 enters and so on. There are like 5 waves or 4 waves. But even that was no good, the first wave may be OK, or may not be, it happens quite randomly.

 

This happens to my desktop and laptop computers, one thing however, they are using built-in network cards.

Brendan Chen

VATPRC Tech Support

You make the difference!

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  • Board of Governors

Maybe a crazy thought, but one that was a past "gotcha" for me where I thought I had "missing" aircraft and then saw waves of aircraft entering the session.... Are these "waves" entering at the limits of your visibility range?

Don Desfosse
Vice President, Operations

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Maybe a crazy thought, but one that was a past "gotcha" for me where I thought I had "missing" aircraft and then saw waves of aircraft entering the session.... Are these "waves" entering at the limits of your visibility range?

 

I am not quite sure, I had seen it once, but the scenario was not developed by me, I was just following what the guy who setup the scenario did... But if that was the case, why would it cause the problems I'd mentioned?

Brendan Chen

VATPRC Tech Support

You make the difference!

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  • Board of Governors

Not sure why the dropouts or why you'd be having issues with so few aircraft; I've just seen waves of aircraft seemingly enter the session because the profile I've used had aircraft outside my visibility range. Sorry I can't be more/any help.

Don Desfosse
Vice President, Operations

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Hi,

 

I used ACSim a few years ago but then moved on to Euroscope's builtin simulator which eases things up a lot. Nowadays I have not problem whatsoever and traffic never dies.

 

I had an onboard network card but it failed a couple of months ago and I had to buy a PCI card to use instead. With one *or* the other, it worked fine, so I wouldn't bet on the saturation issue mentioned.

 

In fact, I was looking at that saturation explanation to eventually solve another issue which we all have and that is when controlling Eurocontrol for instance and having a quite big amount of traffic. The server then disconnects us periodically because it (or our clients) cannot handle the amount of traffic. The new PCI card did not solve this either.

 

Back to the topic, I'd try using Euroscope's built-in simulator. I believe it now accepts both formats (ES or TWRTrainer). otherwise, the simulator file will need "translation" to the ES-format.

 

Miguel

Miguel Frias

Senior Instructor (I3) & Certified Pilot (P4), ZLA I-11 graduate

Portugal vACC Training Director (ACCPT2), VATEUD Operations Director (VATEUD8)

Portugal vACC, VATEUD, VATSIM

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In fact, I was looking at that saturation explanation to eventually solve another issue which we all have and that is when controlling Eurocontrol for instance and having a quite big amount of traffic. The server then disconnects us periodically because it (or our clients) cannot handle the amount of traffic. The new PCI card did not solve this either.

 

The new card did solve the issue for me. It could be that different drivers have a different buffer size (or something along those lines) so not all PCI cards or drivers would solve the issue. Just a theory.

Developer: vPilot, VRC, vSTARS, vERAM, VAT-Spy

Senior Controller, Boston Virtual ARTCC

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Ross, still remember the parameter I could try to modify in order to solve this? I could give it a try.

 

Miguel

Miguel Frias

Senior Instructor (I3) & Certified Pilot (P4), ZLA I-11 graduate

Portugal vACC Training Director (ACCPT2), VATEUD Operations Director (VATEUD8)

Portugal vACC, VATEUD, VATSIM

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