VHF Digital Link Mode 2 (VDLM2)

Data link technology is now the standard in routine communications between flight crews and air traffic service providers. In addition, flight-operations applications—such as graphical weather descriptions, electronic charts, and engine/aircraft health monitoring programs—are commonly used to enhance flight efficiency and safety. Both of these factors have precipitated a strong need for far greater digital bandwidth than is provided by ARINC's existing GLOBALink/VHF service, which uses the character-oriented Aircraft Communications Addressing and Reporting System (ACARS^®) technology.

In response to the additional bandwidth that these technologies require, ARINC developed VHF Digital Link Mode 2, or VDLM2, a bit-oriented, air/ground and ground/ground data link technology that delivers information at 31.5 kbps—over 10 times the rate used by ACARS, the existing character-oriented technology.

Aside from its much greater bandwidth, VDLM2 offers significant advantages over ACARS. Its internationally approved standards-based architecture provides tremendous user flexibility, including complete freedom of choice in aircraft and ground display systems, avionics, and applications. Because it offers a common infrastructure that can be shared by the entire aviation industry, its cost can be distributed over a large pool of users.

VDLM2's expanded bandwidth has allowed ARINC to offer a whole new range of flight information, aeronautical operational control, and air traffic control applications and services.

VDLM2 technology is fully developed. The Aeronautical Telecommunications Network (ATN) VDLM2 service became operational for the U.S. Federal Aviation Administration’s domestic Controller-Pilot Data Link Communications (CPDLC) Build 1 program at the Miami Air Route Traffic Control Center in September 2002. In addition, EUROCONTROL has selected ARINC as the ATN VDLM2 data link service provider over the Maastricht UAC for their LINK 2000+ CPDLC Programme. Also, many airlines are making the transition from legacy ACARS to ACARS utilizing the VDLM2 air/ground data link.

ARINC's VDLM2 service is supported by over 200 ground stations currently deployed throughout the contiguous 48 U.S. states and is expanding worldwide into Europe and Asia. ACARS ground stations are being replaced with integrated ground stations that support both ACARS and VDLM2. ARINC has also deployed an operational VDLM2 network in Japan for AVICOM.

ARINC is making the migration to VDLM2 easy. New data link users or newly equipped aircraft can immediately use VDLM2. For existing aircraft, ARINC is providing ACARS over AVLC (Aviation VHF Link Control)—or "AOA"—service, as well as ATN VDLM2 service. Because operators can continue to use ACARS applications over the VDLM2 infrastructure when using the AOA service, they're only required to make avionics changes; the host systems and existing data link applications require no modification. Operators can transparently support their mixed avionics fleet and preserve much of their investment.

For more information, e-mail globalink@arinc.com.