Link2000 CPDLC in Europe

By Björn Syrén, Göran Carlsson & Kjell Sandberg, SAS

Presentation "CPDLC and Flightdeck work"(1,6 Mb)

SAS aircraft with Link2000 CPDLC

ATC centers with Link2000 CPDLC

Controller-Pilot Data Link Communications (CPDLC) is a system for direct datalink communication between the aircraft and an Air Traffic Control (ATC) center. CPDLC means that routine air traffic instructions and requests are transmitted as datalink text messages, replacing traditional voice communications.

CPDLC allows ATC controllers to manage a larger number of aircraft with less voice radio communication. Communication errors such as simultaneous transmissions, misheard voice instructions and requests are reduced. By sending a text message directly to the aircraft, the ATC controller can communicate traffic instructions clearly without having to repeat the instructions. Workload is also decreased for the aircrew; There is no need to monitor all ATC transmissions on a single frequency and screen out instructions directed to other aircraft, and the crew can read and acknowledge instructions directly sent to them in text.

SAS has joined a Eurocontrol Programme called LINK 2000+ which coordinates implementation of operational CPDLC in the core area of Europe. The Link2000 CPDLC is related to the FANS CPDLC system currently used in North Atlantic airspace. However, Link2000 uses VDL Mode 2 datalink and ATN (aeronautical telecommunications network) instead of ACARS, and is designed to support CPDLC in high-density airspace such as Central Europe.

SAS is initially equipping 20 B737s with VDL-2 and ATN/CPDLC-functionality. The first installation in B737-683 LN-RRZ was test flown and certified 18 Dec 2003.  SAS started operational use of CPDLC in May 2004. Other airlines are expected to have their first aircraft equipped for Link2000 participation during 2004-2005. A total of some 140 aircraft had been commited to the program by mid 2004.

Typical SAS destinations where CPDLC can be used at this initial stage (mid-2004) are: AMS, BRU and CDG. The requirement is that the ATS route takes the aircraft through Maastricht UAC (MUAC).

Examples of uplinked messages from ATC to a/c:

• CONTACT [unitname] [frequency]

• PROCEED DIRECT TO [position]

• CLIM/DESCEND/MAINTAIN FL [flight level]

• SQUAWK [code]

Examples of downlink messages from a/c to ATC:

• WILCO, UNABLE and STANDBY in response to uplinked message

• REQUEST DIRECT TO [pos]

At a later stage it will be possible to request level changes.

The Link2000 operational scenario (2004) in brief:

• The pilot logs-on to ATN 15-30 minutes before entry into the CPDLC airspace.

• The CPDLC connection is automatically established when entering the CPDLC airspace.

• CPDLC messages are then exchanged between the controller and pilot (as required).

• The CPDLC connection is automatically terminated when leaving the CPDLC airspace.

For further information regarding Link2000 go to www.eurocontrol.int/link2000/

During CPDLC test flight, SAS B737-600 LN-RRZ 18 Dec 2003.
Photo by K. Sandberg, SAS.

B737NG cockpit showing pilot interfaces for CPDLC. Upper display unit with "*ATC"
advisory message. The left and right MCDUs are the primary plot interfaces for CPDLC
(also used for ACARS and FMS interface).
Photo via Göran Carlsson, SAS.

Closeup of B737NG upper display unit with "*ATC" advisory message.
Photo via Göran Carlsson, SAS.

Example CPDLC page on MCDU. Aircraft is logged on to Maastricht (EDYY).
Photo via Göran Carlsson, SAS.
(CPDLC HMI design patented by Rockwell-Collins.)

Example of CPDLC page on MCDU. Voice frequency change confirmed by pilot.
Photo via Göran Carlsson, SAS.
(CPDLC HMI design patented by Rockwell-Collins.)

CPDLC test message on SAS B737-600 LN-RRZ MCDU 18DEC2003.
Picture by G. Carlsson, SAS.
(CPDLC HMI design patented by Rockwell-Collins.)

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