ACARS Project Progress

Hoppie Home

Hoppie's ACARS

Buy Hoppie a coffee

My ACARS Account

Client Software

Network Details

Project Progress

Somewhere in November 2023, Hoppie's ACARS quietly passed the 10 million message milestone! Since its inception in the very early 2000s, tens of thousands of users have together exchanged over ten million messages. Quite something to celebrate.

A more specific gap detector is now operational. Users that poll more than once per 20 seconds simply get "no new messages for you" returned for 20 seconds. This does not impact anybody really but reduces the system load as no further database searches or traffic is required.

If your software still has issues with this server fix, please contact me and we will attempt to find a workaround.

Many clients have set their poll rate at 5 seconds and this is simply never needed, please SET IT TO A MINUTE.
more info

I temporarily switched off the connect gap detection as some clients have been programmed with several connections in rapid succession. This is unfortunate because it means the system will again slow down today. As soon as I can, I will make a more complex gap detector that should only block truly harmful client connect bursts. It may lead to brief service interruptions over the coming days.

For client developers: please be considerate when firing off multiple connect() requests in a burst, for example to retrieve several METARs or ATISes. Please insert a bit of delay between them, like a second. The system was never designed to handle multiple clients all using bursts. It easily leads to the well-known "just over the edge" phenomenon where the performance collapses as suddenly everybody starts to pile up.

It looks like there is a new ACARS client out there that is ultra-agressive, both in polling rate and in retries. The number of messages per 24 hours exploded from about 7000 to over 30000 and many are simple duplicates. Usually I see about 30 duplicates in a few seconds coming from the same callsign. All of these are treated as individual messages so this is tough on the system. If you experience slow response, this is probably the reason.

To sort of stop this, I've implemented a mandatory waiting time between polls of 10 seconds. If your ACARS software polls faster, it will get error returns until it slows down. It's crude but it already seems to help.

Please reduce the polling to about once per minute!

New information request: "peatis" for Pilot Edge ATIS messages. New telex workaround: "HC001" to ask for a Pilot Edge ATIS if your ACARS client does not have the "inforeq peatis" implemented (yet). More info.

It remains remarkable that this hobby system, which I started around the year 2000 as part of the (long defunct) Squawkbox for PS1, now has led to a large number of real wide body aircraft to routinely cross the oceans under ICAO PBCS rules. In 2011 I made a career switch to start developing real avionics for real aircraft and over a hundred wide bodies now fly my software. No it is not the same ACARS software that runs on "my" Iridium SATCOM gear aboard these planes, but it surely is the same concept, the same thinking, and the same design principles. Sometimes, a hobby really teaches you how to do things properly.

It seems that IVAO fixed the bug. Lately I see no more binary garbage messages at all. Good!

I'm tracing a probable bug in an ATC program used by IVAO (only). It seems to attach random binary garbage to CPDLC messages, which often but not always leads to the ACARS server simply discarding the message. It is not just accented letters or so, it really is a couple of dozen binary bytes that look like random memory, previously used to contain various other things such as HTML. As in, a few random stack frames until there was a zero. If anybody can suggest which program this may be and who is its developer then we may be on our way to fix it.

As most airplane or controller software for Hoppie's ACARS is provided by third parties, I started a list of client software. Please help me out by submitting known client programs to my e-mail address.

He's back. Fun.

After 20 years, the funny people of the internet have found that bothering others during their hobby is a wonderful way to pass the time. I had to shut down various parts of the ACARS system to dim their enthusiasm a bit. Hopefully they will grow up and we can restore the system to what it can be as long as everybody behaves like an adult.
I am not considering blue or gray or purple check marks yet.

Thanks to the cooperation of many people, the ACARS system has stabilized nicely. With over 15,000 registered active users and regularly over 700 users online at the same time, the small server doing all the work rarely exceeds 50% load. Not bad for a design that is over 20 years old.

A bug in the ping command prevented network filtering for stations online. Thanks to Jonas Kuster for pointing it out. The dispatch file stores still need to get the same modification and I hope to get this done this week.

As ACARS popularity keeps increasing, a few new guidelines have been written to better keep the server load in check. This is mostly relevant for the developers that write ACARS client software. See the technical documentation for details.

Work has started to include the network affiliation of the ACARS users into the system logic. For a while, multiple virtual airspace organisations have been using this ACARS system at the same time, which of course causes clashes for airport names if they are staffed on more than one network. Adding one network affiliation per user should go a long way in solving this.

If you want to discuss this technically, please join at this Forum: Aerowinx 744 Forum.

A repeat of an older message to get it back on top of the list:

If your ACARS claims "PLEASE UPDATE YOUR ACARS URL SEE WWW.HOPPIE.NL/ACARS", then your old ACARS client software still refers to a network connect URL with 'flightline' in the string. Please replace this by the correct URL:

Since most of the ACARS client software in use today is not written by me, I will usually not be able to help you with the URL update. Please consult your software supplier for the instructions.

Today I looked at the counter of active accounts, which shows the number of accounts that have seen activity in the last 90 days. ACARS currently has over 3000 active users! There are over 800 users registered that have never logged on yet, most of these probably never will and these passive accounts will expire automatically after 90 days of passiveness.

Netcraft has officially withdrawn their complaint and determined that their warning nr. 6025501 was a false positive.

There are suddenly warnings floating around that the ACARS-for-MSFS single installer, available from, is a malware distributor: As far as I can track it, it was last restored from backup in February 2018 when I moved my server and it still is the same as when I originally compiled it in August 2010. Even the Wayback Machine has exactly the same file dated 2016.

The inevitable happened: some funny guy (statistically it must be a guy) has used the ACARS system to spread offensive stuff among unsuspecting pilots. As the system was not designed to weed out jokers with surgical precision and ban them for good from the planet (there was no Facebook or Twitter or Google with omnipotent identity cancelation powers 20 years ago), I am currently contemplating how to stop the comics. So please beware the jokers and give me some time to come up with a workable solution that fits in with our hobby. What do pilots do when there is a joker on the frequency? (hint)

I added TLS (HTTPS) to the web server. However, many client software packages do not work yet with HTTPS, so you may try but the URL below is what is guaranteed to work.

Nothing changed, except the hardware, operating system, database, programming language revision, country of the server location, IP address, and some other details of the system.

IMPORTANT: older (>10 years) ACARS client software still refers to a network connect URL with 'flightline' in the string. Please replace this by the correct URL:

It is that time of the year again. ACARS and a lot of other systems are being set up to support WorldFlight 2013 as usual. Please take a moment to look into this major online event and fly along if you can!

ACARS has been switched into Worldflight Mode. This means that some lists and most maps are now only showing aircraft known to participate in Worldflight. If you participate and do not get listed, just mail me (address at the bottom of the page).

Due to an unexpectedly loud default sound level, the ATC (CPDLC) application turned out to be rather jumpy. I added a volume control slider to the Setup dialog. Version 1.5.1, here.

It is that time of the year again ... while the teams prepare for their epic journey around the globe, the ACARS system undergoes maintenance to make it ready for 24/7 support of the logistics.

V1.9 of the aircraft client fixes up a few snags in the formatting of position report times and the inflight ETA. It also offers a convenient shortcut if you manually update the ETA and want to send the OOOI report ahead of automatic time.

V1.8 of the aircraft client integrates VATSIM ATIS requests. This feature is still being fine-tuned at the server site, it will improve over the next days.

This date marks the moment in time that I officially crossed over from doing hobby ACARS in Europe, to doing professional (Iridium SATCOM) ACARS in the USA. In hindsight from 2023, who would have dared to predict the results?

V1.4.1 of the ATC client offers a poll interval setting in milliseconds.

ACARS just reached the 400 active accounts mile stone. Thanks to this rather large user base for such a niche system, I am still committed to keep it running!

ACARS has been switched back to normal operation after a brilliant World Flight 2010. Hope to see you all next year!

Worldflight 2010 has been made active on ACARS. Some features, such as some maps, are dedicated to just Worldflight aircraft until Sunday November 7. If you want to join Worldflight, just send your aircraft callsign to More info at my Worldflight blog.

In preparation for Worldflight 2010, I've added (guarded) Twitter bridging to certain ACARS message types linked to certain accounts (logon codes). To follow Worldflight, use for example

A new documentation page was added to explain how to enable the ADS-C transmissions from an aircraft, so that it appears on the global aircraft position map.

The ATC client has been updated with various usability features. The most noteworthy ones are: 1. transparent secondary windows, 2. options to make the secondary windows less intrusice, 3. Reply-via-CPDLC button in Telex (ACARS).

I am busy adding interface sugar to the ATC program (the CPDLC client) to facilitate the integration with any radar scope out there. Controllers are invited to participate in the development by downloading the client and giving feedback on the VATSIM forums (Controller Talk, preferably).

By popular demand: the ACARS all-in-one installer for MSFS. Now you just download one package and do next-next-finish to get it all running. Ok, you still need your logon code.

ACARS is getting more popular. After several years of putting myself in between the logon code requests and the ACARS system, I took the plunge to open up the self-service registration. Hopefully the trolls stay away.

World Flight 2009 is coming up fast. As always, ACARS plays an important role in this event. Operationally it is used to coordinate many issues, and the maps it generates are very nice for event dissemination. There is more information online about how to use ACARS during WF2009.

To facilitate nice maps for web sites of Virtual Airlines, I added a feature to the world map. You can now filter for all airplanes that share the prefix of a callsign, such as "BAW".

A research project at George Mason University (DC) required a shorter polling cycle than 60 seconds. The new acars.pollintv configuration setting of the ACARS Airborne Client, which is not available in the Setup dialog for safety, allows you to adjust this cycle time in milliseconds. 60000 is the default. Don't use this on the ACARS network unless you make sure you don't overload the server. V1.7.1 of the Airborne Client (only).

One of the long-standing ToDo items was to enable the ATC position report. It is now an exact copy of the FANS-1 variant, which is shared between FMC PROG, FMC COMM, and ATC modes (and therefore cannot return to anything, just as in reality). V1.7.

In preparation for World Flight, I added a VisualPS1 offset detector to the ACARS Airborne Client V1.6. This is only of use for people who use VisualPS1 with IPC 2.8, probably just two on the Earth. All the others may leave this selection in Setup undefined.

ACARS Mini Server full "ping" implementation, which enables the ATC client to not time out planes that are quiet but remain online. Release 0.4.

The CPDLC system got a significant extension: ATC stations may now relay route files to planes via CPDLC. Of course not all sims know how to handle route files, but this is "not my problem" :-). Both a new ATC station and a new Airborne Station required.
Also significant improvements in terms of ADS-C in the Airborne Client. This stuff now goes only to the network server but may eventually also appear in the ATC client.

V0.3 of the ACARS mini server fixes an irritating bug that blocked all CPDLC message exchanges. A case of trying to be too clean in data sanitising...

Dispatch has a new release, with the option to change the sound file now in Setup, and also the option to change ACARS servers. Typically you want "localhost" if you run the mini ACARS server yourself.
The CPDLC (ATC) client also got released with a few things, mostly the configurable ACARS server setting. Same for Airborne.
And of course the ACARS mini server itself, currently at 0.2.

In preparation of the new ACARS mini server, the Airborne Station got the option to select a different ACARS server URL. Also added a switch to select pure UTC time on the clock, instead of listening to a connected simulator. The program is now called differently and installs in a different location, which will be my new installation pattern.

New Dispatch Client, updated with recent developments around TOPCAT and such, sound, and now packaged with a Windows installer. Also new Airborne Client, with manually editable OOOI fields in case you don't have working data feed.

Airborne 1.2 has integration with TOPCAT and also allows downloading FMC route files for other sims than PS1.

Better internal structure leading to bugs fixed in the airborne client.

Bugs fixed in the CPDLC client (ATC) that mixed up the effects when a CPDLC message came in with those for telex.

Pre-Departure Clearance added, printing logic restored to a sane state, and a few minor cosmetical fixes. V1.0 with Windows installer. Armable reports still absent, which probably nobody will notice anyway.

Emergencies and When-Can-We added, ATC keystroke logic improved (the MCDU cannot detect holding the ATC key down, but it can detect pushing it twice within two seconds -- this will get you to the Emergency page straight away). Many smaller things fixed up. It now gets somewhere. Major thing lacking: armable (automatically sent) reports. 0.7.5.

Reports added and Verify totally rewritten in the airborne client 0.7.4.

Small polishings and a Windows installer instead of a plain .zip file.

Full addition of the telex capability so that controllers have both communication systems in one client program. Sound library still not configurable except by overwriting the meepmeep.wav file.

Quick and dirty addition of a sound when a CPDLC message comes in. Will get configurable. Please report whether it works.

Airborne client up to 0.7.2. Fixed a problem with complete ATC log printing (from the ATC Index Page) and added some white space at the bottom of each print, for typical flight deck printer form feed.

Airborne client up to 0.7.1. Can now print and some leftover items from SB747 have now been removed.

ATC client up to 0.7.1. Now has usability improvements for departure clearances and other long messages that repeat often, window management aimed at ATC scopes, and messages to planes not yet logged on.

New releases 0.7 of airborne and ATC clients. Plane handover between centers included (look into the COMM message cluster) and lots of loose ends tied up.

New release (0.6) of airborne and ATC clients. All required functionality is in there now, just a few bells and whistles missing.

Busy redoing the ACARS web site. It was a mess, getting better now.

The latest beta release of the airborne client gets closer to what it should eventually be. Serious usage of this is possible by now. The web site is getting better, slowly.

As I slowly fix all open issues and add more and more pages to the airborne side of CPDLC, the thing becomes actually usable.

CPDLC beta released, both ATC and aircraft side. Still needs work though.

Start of ACARS revamp, including all web sites.

© 2024 Jeroen Hoppenbrouwers For more information, mail to