WACARS and/or AirNav with your soundcard


(Windows Aircraft Communications Addressing And Reporting System)

The sound your are hearing now is a (W)ACARS signal ...

(Partial screendump) Click on the picture to see all and more details (61 kB)



ACARS is a digital 2400 bps data link system transmitted via VHF and HF radio which allows airline flight operations departments to communicate with the various aircraft in their fleet. This VHF / HF digital transmission system, used by many commercial/civilian aircraft and business jets, can be compared to "email for airplanes," as the registration of each aircraft is it's unique address in the system just like the call signs of a amateur radio operator. Traffic is routed by ARINC computers to the proper company, eliminating some of the routine voice communication with the company. With ACARS, such routine items as departure reports, passenger loads, arrival reports, fuel data, engine performance data, and much more, can be requested by the company and retrieved from the aircraft at automatic intervals. Before ACARS, flight crews had to use voice communications to relay this data to their companies on the ground.

APRS was invented and developed by Bob Bruninga, WB4APR. Any hamstation that runs transmits a beacon APRSwith its position data. Even when a station is portable or mobile, it can combine a GPS with their hamradio, making it possible to track it. Although APRS was originally designed for positioning, it was extended for sending messages (sends automatically your callsign and receives an acknowledgement), weather data, etc... All data transfer is via packets at 1200 baud in UNPROTO mode (UNPROTO means non-addressed). These packets are received by digipeaters and re-transmitted making it possible to 'see' stations at large distances. You can even go online to watch APRS traffic all over the world ...

If you have AGWPE installed and if you own a simple airband receiver or scanner, capable of reeiving 131.725 MHz (frequency mostly used in Europe), it requires only a little effort to see air traffic.

How to get ACARS in your shack ?

I assume you already downloaded and installed AGWPE. If not, use the back button of your browser and go to the 'Windows settings and AGWPE' section.

Next, you need an ACARS program, for which i use WACARS (screendump : see above), which is freeware, but you will get your registration code by sending a simple request by e-mail to the authors. More details on this can be found in the 'Help' section or the readme.txt file. Now, follow the next steps to make WACARS work properly with AGWPE.

So, download WACARS by clicking on the picture below, unzip all files in a directory and run the program. In what comes, i will assume you want to work with your soundcard, so in the direct mode, not via the online modus of the program.

WACARS v0.7 (358 kB)


WACARS is written for use with a soundcard, so you do not have to run AGWPE first !! If you do, the WACARS software will tell you it didn't find a soundcard (since it is in use by AGWPE at that moment).

The first time you use WACARS you might need to find the best audio levels for the computer and receiver. Using the mixer control for your soundcard adjust the appropriate input gain and the master gain to about 1/2. Also make sure that the "Line–in" is selected as an active input for recording. Next adjust the volume of the receiver such that when a strong ACARS signal is present the SIG meter moves to the middle. With no ACARS signal present the SIG meter should show no signal. This is a good starting point, but by adjusting the different volumes you may get slightly better reception. You can save your soundcard settings with QuickMixIn, described and downloadable at the 'Windows settings and AGWPE' section of this webpage. It will make it easier to switch between different programs without having to tune your soundcard every time ...

That is all ! The WACARS screen consists of five different windows. The SIG and CPU meters display the signal strength and the CPU loadings. The Raw Data Log shows any data detected from a received ACARS signal. If the received data forms a correctly formed ACARS packet it is then decoded and displayed in the ????MESS.LOG window. Data in this window is also automatically saved to disk in a file ABDCMESS.LOG, where AB is the date of the month and DC is the month. The registration of the aircraft is extracted from the ACARS packet and stored in the sorted list of aircraft detected, the Aircraft Contacted window. The flight number of the aircraft is also extracted from the ACARS packet and stored in the sorted list of flights detected, the Flights Contacted window.

In the 'Links' page of this website, you will find more interesting links on WACARS software, general info and maps.


AIRNAV (Air Navigation)

(Partial screendump) Click on the picture to see all and more screendumps (137 kB)



AirNav is the most sophisticated program to be used by the ACARS enthusiast.
It has extensive menus in which you can choose your data input source (internet or real-time using your airband receiver), make new digital maps, make list of flights heard, very detailed step-by-step tutorials, aircraft and flight databases, ... In what follows, only the method to get the data input from your airband receiver will be discussed briefly. The programitself, AivNav is NOT freeware, and after a trial period you will have to register. It can be downloaded from the internet at the following URL : http://www.airnavsystems.com. This site also contains lots of info on AirNav and links for maps etc.

How to get AirNav in your shack ?

1. Real-time input for AirNav works via FWD (File Write Detection). This means that AirNav continuously reads the log file that is generated by another program and uses that for its own purposes. So you will first have to start e.g. WACARS as described above.

2. Be sure that in WACARS you have 'Airmaster Mode' turned on (under 'Options' in the menubar).

When Wacars receives data, they are stored in a log file using the following format (a so-called Airmaster compatible log file) :

ACARS mode: 2 Aircraft reg: .N374AA
Message label: 10 Block id: 9 Msg. no: 3644
Flight id: AA0998
Message content:-
IS MIA /FQY31550

This file is named XXXXmess.log where XXXX stands for 4 numbers, indicating the month (two first) and the date (two last). For example, when you start WACARS on 14th of March, a file 0314mess.log will be created and maintained during operation.

3. Start AirNav and click F2, so that the RealTime Interface window is opened. An example of this window can be seen when clicked on the AirNav partial dump picture above. Now, open the menu 'Source Data' and click on 'Live Data from WACARS'. (You can also import a previous file to be displayed in AirNav in the same menu). After a warning to remind you that in WACARS the Airmaster mode has to be turned on, the program asks you whether the file given is the one that is being written by WACARS. Usually, you only have to choose for 'Yes'. If this is not the right one, just choose 'No' and browse to the log file you want to be used. Close the window by pressing F2 again.

4. In the main program, go to 'Maps' and choose for 'Open Map'. Load the map you want to be displayed in the main window. You can open several maps at the same time, which can be usefull e.g. to open a general view and a detailed map view simultaniously.

When using the program, you can always click F2 to follow the incoming messages. Note that not all messages give enough data to be displayed on the map. Only when a little earthglobe appears next to it, the plane will be given graphically. Once a flight is spotted, you can, amongst many others, ask for details on the aircraft and the flight, track it, ...Moving the cursor over the plane in a map gives only brief information. The program AirNav has almost unlimited possibilities for aircraft spotters and/or trackers. In the manual you can find all details on these extensive pull-down menus.

Last updated on December 23th, 2006 by Ronny Stobbaerts