• Aircraft data link communications compliment voice communications between the aircraft and ground facilities by providing a faster, more accurate means oftransmitting and receiving information
• 31.5 Kbps data rate (VDL Mode 2) is the fastest VHF data rate available today
• Two way text messaging and storage; allows messages to be retrieved and viewed at later time when detailed information is needed
• Uplinked textual and graphical weather information to support strategic and tactical flight planning
• Improves flight following via automated off/on ground and position reporting and SELCAL capability
• Reduces flight crew time spent on passenger service requests
• Stores and downlinks fuel status and engine trend data
• Provides fast, efficient Air Traffic Service communications, including ATIS and TWIP reports, departure and oceanic clearances and ATC advisories
• Provides an on-board printer output
• Growth to support CPDLC, Link 2000+ and FANS 1/A
• Compatible with multiple communications service and content providers (ARINC, SITA, Universal Weather, Global Data Center, etc.)

The CMU-4000 is a state-of-the-art data communication management unit designed to provide a transition with minimum cost of ownership as the world-wide data link system evolves from ACARS to ATN. The CMU-4000 is capable of managing data link communications over all three RF subnetworks (VHF, HF and SATCOM). The airborne system consists of the CMU-4000 and associated equipment including radios, control/display units and other computer systems as required for specific applications. Three ground information sources communicate to and from the aircraft: air traffic services, airline operations centers and commercial service providers.

The CMU-4000 provides hardware and software provisions to run multiple applications simultaneously. Multiple links (VHF, HF, and SATCOM) are automatically established, continuously maintained, and can be used concurrently. The CMU-4000 is capable of using either "Plain Old ACARS" or high speed ACARS (AOA) over VDL Mode 2. Software upgrades will allow for concurrent ACARS (AOA) and ATN (CPDLC and other applications) over VDL Mode 2.

The CMU-4000 supports the following:

• ACARS per ARINC 618, VDL Mode 2 per ARINC 631
• VHF per ARINC 750, SATCOM per ARINC 741/761, HF per ARINC 753
• CDU and MCDU per ARINC 739
• Cockpit Printer per ARINC 740/744A (full format with graphics capability)
• ATS services per ARINC 623
• Existing and emerging data centers for weather and flight planning related services