Controller-Pilot Data-Link Communications at Maastricht UAC

Voice communication – exchanging information verbally – has until now been the most widely used means of communication between air traffic controllers and pilots. Over time, and with traffic growth, this technology has shown its limitations.

To address these, EUROCONTROL has developed Controller-Pilot Data-Link Communications (CPDLC) - an air/ground data-link application currently used at the Maastricht Upper Area Control Centre (MUAC), which enables the exchange of text messages between air traffic controllers and pilots.


CPDLC offers the benefit of an additional, independent and secure channel, which reduces the strain on busy sector frequencies, transmitting clear messages with no risk of misunderstandings. Use of the system increases capacity and improves the day-to-day efficiency of communications between controllers and pilots.

Our data-link services

Access: To operate controller-pilot data-link communications with MUAC you need to have certified future air navigation system (FANS) or aeronautical telecommunications network (ATN) data-link avionics on-board your aircraft, and adhere to our operational procedures (read the Acceptable means of compliance) . If you fulfil the criteria, contact us for further information.

Issues: The Data-Link Services Central Reporting Office (DLS-CRO) monitors data-link operations and resolves issues affecting safety, capacity, performance and interoperability at European level. Problems can be reported on the system dashboard or by contacting us.

Statistics: CPDLC has been in operation at MUAC for 20 years. Approximately 5% of the traffic exchanges CPDLC messages with MUAC. If you wish to receive more statistics, contact us.


The MUAC CPDLC log-on address (EDYY) offers data-link services 24/7 to all aircraft equipped with the appropriate CPDLC avionics in the upper airspace (above FL 245) of:

  • the Brussels Upper Flight Information Region (EBUR UIR),
  • the Hannover Upper Flight Information Region (EDVV UIR), and
  • the Amsterdam Flight Information Region (EHAA FIR).

Message types

Our CPDLC operations support the following message types:

Data link integration capability (DLIC) Log-on is a prerequisite for operational data link services via the exchange of address information in order to establish flight plan/address associations in the ATC system, ensuring correct message delivery.
Air traffic control clearance (ACL) enables the air traffic controller to issue climb/descent clearances, direct clearances, turns and headings and SSR instructions, or to reply to aircrew requests. The ACL service also enables the aircrew to make operational requests and to respond to ATC clearances and instructions.
Air traffic control communication management (ACM) supports automated controller/aircrew communications hand-off, via both R/T and data link, from one sector/centre to another.
Air traffic control microphone check (AMC) provides air traffic controllers with the capability to uplink an instruction to check that pilots are not inadvertently blocking a voice frequency/channel with a “stuck microphone switch”.


The CPDLC programme at MUAC supports data link via FANS (Future Air Navigation Systems) and the ATN (Aeronautical Telecommunications Network).

The MUAC CPDLC log-on address is EDYY. It covers the whole area of responsibility of the Brussels, and Hannover UIRs and the Amsterdam FIR. The ICAO call sign must be used exactly as it appears in the flight plan.

Flight-plan information The aircraft registration REG/... [FANS] or CODE/... [ATN] must be provided in Field 18 of the flight plan, to ensure the correlation of data link messages.
CPDLC initiation Logging on to the system is a prerequisite in order to establish the aircraft’s flight plan and ensure correct message delivery. After becoming airborne, the aircraft logs on 10 to 15 minutes before entering the airspace of MUAC. The ground system then initiates a CPDLC connection and the aircraft responds to the ground system with a message which is automatically generated by the airborne avionics.
CPDLC initiation time After completion of the CPDLC initiation, the ground system attempts CPDLC connection some 10 minutes before the aircraft enters the airspace. For aircraft departing from an airport located close to the airspace managed by MUAC, the CPDLC connection will only occur above FL 150, to minimise crew distraction.
CPDLC current data authority (CDA) Following confirmation of the CPDLC connection, the ground system automatically receives a current data authority (CDA) notification, informing ATC that the aircraft is ready to conduct CPDLC. During the log-on phase, the CPDLC connection and CDA sequence are normally conducted outside the MUAC airspace. Aircraft must be under the control of a controller in Maastricht before any actual CPDLC exchanges can occur. Besides the voice trigger of the instruction to “Contact Maastricht on ...”, aircrew can also tell from the CDA change that they have come under the control of MUAC.


CPDLC Support team

Horsterweg 11
6199 AC Maastricht
+31 43 366 1510