ACARSd was written by one person.
It was built by a community.
The code has an author's name. The project has many more. Testers, server operators, aviation-data maintainers, radio enthusiasts and fellow developers supplied difficult signals, compared results, corrected databases and kept the network alive.
Help us preserve the ACARSd years.
Did you use ACARSd, operate a public server, test a beta, contribute aircraft data, exchange e-mails with KjM or simply spend nights watching messages scroll across the screen? Please send a few lines about what you remember. Include your name or old nickname/callsign, approximate location and years if you want them published.
Send your memory to acarsd@acarsd.org
Nothing will be published automatically. Contributions can be edited or withheld from publication on request.
A very personal thank-you.
Some people communicated with KjM almost daily during the intense development years. They supplied the feedback loop that made ACARSd better: real-world reception results, missed messages, database corrections, technical explanations and the occasional challenge that became a new feature.
Thank you to Ralf and the people around Airframes.org for the aircraft-data work and the exchange of knowledge that helped turn raw messages into useful aircraft context.
Thank you to the developer(s) of ANAD. What began as a benchmark and competitor relationship grew into professional respect; later, even pre-release ADS-B test software was made available for ACARSd-related testing.
An accidental e-mail from Gábor in December 2002 contained the ANAD report that first made KjM ask how aircraft movements could be received at home. It was not meant to start a software project. It did.
Thank you to everyone who compared decoders, captured difficult audio, reported false or missed messages and ran experimental builds. The multi-pass decoder was shaped by those real signals.
Ingo co-authored the aircraft position calculation and plotting routines in ACARSClient. The surviving source says it directly: “Position calculation and plotting source — Written by Ingo Richardt and Kai-jens Meyer.” His work helped turn occasional ACARS latitude/longitude reports into aircraft symbols and tracks on a live map years before web mapping APIs became commonplace. Thank you, Ingo.
For many years, René worked on the flight and aircraft databases that gave decoded messages their context. He was also a dependable helping hand whenever ACARSd needed something done — from small jobs to much larger tasks. Thank you, René, for years of data work, practical help and support.
Thank you to everyone who opened port 2202 and made a receiver available to strangers on the Internet. Without those stations, ACARSd would have remained a decoder instead of becoming a network.
Names still to recover.
Twenty years later, some names are easier to recover than others. The museum deliberately avoids inventing them. Airframes.org's operator is identified in surviving community discussions as Ralf; the full historical attribution and the ANAD developer's name will be added when a primary or sufficiently reliable source is recovered.
If you recognise yourself — or know one of the missing names — please get in touch.
In memoriam.
Ingo worked with KjM on ACARSClient's aircraft-position calculation and map plotting. The source preserves both names together. He died in 2011. The museum remembers a collaborator whose code helped put aircraft onto the map.
Karl was KjM's boss and friend at SWF3 Online. A fierce argument over a Perl web counter pushed KjM to teach himself C — a chain of events that ultimately led to ACARSd. Karl died unexpectedly years later. The argument faded; the friendship and its consequences remained.
Future exhibit: Voices from the ACARSd years
This page will grow into an oral-history wall: short recollections from former users and contributors, preserved alongside the code. Technical projects are usually archived as binaries and source trees. What disappears first is the human context: the late-night e-mails, the receiver on a windowsill, the first successful decode, the public server that somebody kept running for years.
Those memories are part of the project too.
Dr. Armin Zundel, Prof. Kay Berkling and INLINE — the support behind the hobby.
ACARSd was never a commercial INLINE project. It did not earn the company money; if anything, INLINE invested in it. KjM's boss, Dr. Armin Zundel, supported the project, provided the web presence without charge and often helped when the decoder or the surrounding system needed improvement.
Armin is a mathematician, and that produced one of the more entertaining technical disagreements in the project's history. He was convinced that the proper way to attack the ACARS audio signal was with a Fast Fourier Transform. KjM, who had taught himself C from the Apache source code, was considerably less enthusiastic about the mathematics.
Armin was not alone in that experiment. His wife, Prof. Kay Berkling — a computer scientist whose work includes speech recognition — also helped with the FFT approach. The earliest surviving ACARSd README already thanks “My Boss” for explaining the sound signals and “My Boss Whife” for help with FFT, followed by the wonderfully dry note: acarsd is still running without it. They tried FFT anyway. The surviving source archive still contains the remains of those experiments. But the approach never delivered the practical results they wanted, and the production decoder ultimately evolved around a different idea: multiple empirically derived code tables, multiple decoding passes and adaptive prioritisation of the combinations that produced successful messages.
And there was Tcl/Tk.
Armin also introduced KjM to Tcl/Tk in a completely different context. His idea was to build a community system in Tcl/Tk instead of Perl or PHP because it would be exceptionally fast. KjM remembers complaining loudly about the idea — until Tcl/Tk eventually became fun. Years later that experience returned in ACARSClient, where Tcl/Tk powered the portable GUI, map, databases and the secret game launcher.
Source note: this origin story is KjM's 2026 recollection; the resulting Tcl/Tk client code is preserved in the ACARSd source tree.
Some projects survive because somebody lets them grow.
Armin never dismissed ACARSd simply because it was a hobby and had no business case for INLINE. Infrastructure, technical discussion and the freedom to experiment all mattered. Thank you, Armin — and thank you, Kay.