Black Cat Systems

Follow our tweets!

Lost Reg Code?
Online KiwiSDRs
macOS Software
Windows Software
Ham Radio iPhone/iPad
Linux Software
Update Policy

USB Icom CI-V Interface

Radio Hobbyist Products

  22m Programmable Beacon Kit
  22m Part 15 Beacon Kit
  CW Keyer For Beacons Kit
  Jellyfish Transformer
  Cyclops Antenna Transformer

General Interest Programs

  Atomic Mac/PC
  Audio Toolbox
  Black Cat Timer
  Diet Sleuth
  Graph Paper Maker
  Health Tracker
  Image Resizer
  Knitting Wizard
  Label Wizard
  Prog Audio Gen
  Sound Byte
  Synth 76477

Amateur Radio Programs
  AirSpyHF+ Server
  Black Cat ACARS
  Black Cat ALE
  Black Cat ALE Vacuum Cleaner
  Black Cat NetFinder
  Black Cat GMDSS
  Black Cat HF Fax
  Black Cat SSTV
  Carrier Sleuth
  Cocoa 1090
  Cocoa RTL Server
  DGPS Decoding
  DX Toolbox
  eQSL Factory
  KiwiSDR Monitor
  KiwiSDR Sound Client
  Morse Mania
  RF Toolbox
  SDRuno Plugin
  SDRuno Equalizer Plugin

iPhone/iPad Apps
  Atoms To Go
  dB Calc
  Clik Trak
  DGPS Decoder
  Drill Calc
  DX Toolbox
  Elmer Extra
  Elmer General
  Elmer Tech
  Feld Hellschreiber
  Field Strength Calc
  Function Generator Pad
  HF Weather Fax
  Morse Mania
  Morse Pad
  Packet Pad
  PSK31 Pad
  SSTV Pad
  Photon Calc
  Rad Map Tracker
  RF Link Calc
  SelCall Tone Gen
  Sound Byte
  Sound Byte Control
  Spectrum Pad
  SWBC Schedules
  Synth 76477
  Synth Motion
  Transmission Line Calc
  Weather Calc
  Wire Calc

iPhone/iPad Bundles
  RF Calculator Apps
  Ham Radio Decoder Apps
  Audio Utility Apps
  Shortwave Weather Apps
  Ham Radio Exam Study Apps
  Shortwave Decoder Apps

Android Apps
  Audio Function Generator
Audio Spectrum Analyzer
DGPS Decoder
  HF Weather Fax
  Rad Map Tracker
  SelCall Tone Gen
  Sound Byte Control
  SWBC Schedules
  Wire Calc

About Black Cat Systems
Site Map
Our software for Mac OSX
Privacy Policy
Apple /// Emulator

Macintosh Links
Shortwave Radio
Pirate Radio
Spy Numbers Stations
Science and Electronics
Ham Radio Software


Receiving / Decoding ACARS Transmissions from Aircraft With Your Macintosh


One of the more interesting digital modes that can be monitored are ACARS transmissions from commercial aircraft. Many of the routine messages that were formerly sent by voice are now sent by an ACARS digital link between the radio and ground. This messages can be received on any scanner type radio that tunes the VHF Aircraft band (118-136 MHz) using our MultiMode software, without the need for extra hardware.

You'll need a radio that tunes the above-mentioned band, in AM mode. Most scanners will do this fine. You'll then need to connect the audio output of that radio into the sound input (microphone) jack of your Mac. If your Mac doesn't have sound input, you can always use an iMic or other USB based sound input device.

Next, fire up a copy of MultiMode and selec ACARS mode.

Now, tune your radio to one of the ACARS frequencies. There are several to choose from:

131.550			Primary Channel worldwide
130.025			Secondary channel for USA and Canada
129.125			Additional channel for USA & Canada
130.450			Additional channel for USA & Canada
131.125			Additional channel for USA
136.700			Additional channel for USA
136.800			Additional channel for USA
131.725			Primary channel in Europe
131.525			European secondary
131.475			Air Canada company channel
131.450			Primary channel for Japan
136.900			European secondary
136.925			ARINC European Channel
136.850			SITA Canadian Frequency

Next you'll want to know what you should be hearing. Click here to listen to a typical ACARS packet You'll find that weekdays are the busiest times to listen, often you can hear a packet sent every few seconds. Due to the height of aircraft (30,000 feet or more), their ACARS transmissions can be heard for great distances, up to a few hundred miles.

Many of the messages are routine, such as:

.N643DL  Q0 0   [26 Jan 2004   16:28:05][DAL Boeing 757 23997]
S77A DL2581  
N643DL is the tail number of the plane. Q0 0 is the message type. The date and time are automatically stamped by MultiMode. The aircraft database file that comes with MultiMode has identified the tail number, and displayed information about the airplane, which type it is. Finally the message itself is displayed on the next line.

Some of the messages are less routine, and more interesting. I won't divulge any here, but they include unruly passengers, and equipment failures onboard the aircraft, usually involving the lavatory.

ACARS is a fun mode to monitor, and quite easy. Just connect your radio to your Mac, run a copy of MultiMode, and sit back and watch the messages. You can even set up MultiMode to automatically write all the information received to a log file, so you can monitor unattended, such as during the daytime, and then come back and view what has been received.

Return to MultiMode

Return to Black Cat Systems
Chris Smolinski