Classic Aero AES Subsystem (CAAS)

The Classic Aero AES Subsystem (CAAS) software implements the core of an Inmarsat Aircraft Earth Station (AES) as defined in the Inmarsat Aeronautical System Definition Manual (SDM). The Inmarsat Aero system provides communications for passengers, airline administration, aircraft operational control and air traffic control services (safety services). Over 8,000 aircraft, including almost all of the world’s long haul aircraft, are fitted with Classic Aero terminals. For more information on Inmarsat’s aeronautical services, click here.


The CAAS supports the following functionality:

  • 600, 1200 and 10500 bps P/R/T-channel physical layer
  • 8400 bps C-channel physical layer
  • AES management protocols, including log-on/off handling and handling of the System Table and Spot Beam map
  • Data link layer protocols for P/R/T-channels
  • Data-2 / Data-3 services
  • C-channel protocols
  • Delayed Echo Application (DEA) for link layer protocol testing
  • Test modes for physical layer testing (e.g., transmission of CW)

As it is used to provide ICAO safety services, the CAAS software has been developed to DO-178B level D.  It is flying on commercial air transport, business and military aircraft


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