Controller Pilot Data-Link Communications (CPDLC)

Today’s fast-paced world of avionics often requires pilots to correspond with ATC in a variety of formats, including data-link communications. SERA’s CPDLC add-on package simulates and automates CPDLC communications; as a result, instructors no longer need to role-play ATC messages. This article defines CPDLC and discusses training benefits and simulator integration options for SERA’s CPDLC package.

What is CPDLC?

The International Civil Aviation (ICAO) Document 4444, “Procedures for Air Traffic Management,” defines CPDLC as “a means of communication between the controller and pilot, using data link for ATC communications.” Controllers use this method as an alternative to voice communications, transmitting nonurgent, strategic messages to the aircraft’s Multi-Function Control and Display Unit (MCDU):


B747-400 FANS Display (photo credit)

Pilots can respond to messages, request/receive clearances and information, and report information. A “free text” capability sends messages that don’t conform to defined formats.

This air/ground data-link application functions as an additional, independent, and secure channel. CPDLC reduces traffic on busy VHF sector radio frequencies, transmitting clear messages with little risk of misunderstanding. Not only does it increase capacity and safety, but it also improves day-to-day communication among controllers and pilots.

Which training benefits does SERA’s CPDLC package provide?

The burden of role-playing both ATC voice and data-link communications usually falls to instructors. Unfortunately, managing the open dialogue of both formats in a single exercise can be tedious and frustrating. Many exercises only address one format at a time, and the resulting experience falls far short of reality.

SERA offloads this responsibility, enabling instructors to focus solely on training objectives. Student pilots learn to multitask in the cockpit, responding to both message formats in real time. AI entities behave just like actual controllers: if a pilot doesn’t respond to a data-link message, ATC follows up with a radio call.

SERA provides a hardware or software interface with fully simulated CPDLC capabilities. A built-in API sends and receives standard message sets defined in ICAO 4444 16th Ed., Appendix 5, including the FANS 1/A+ and ATN B1 standards. SERA’s database includes a comprehensive directory of controllers, reducing time-consuming configuration and setup.

ASTi’s SERA CPDLC package supports a variety of capabilities:

  • Data-Link Initiation Capability (DLIC): included as a prerequisite for all other CPDLC functionality
  • ATC Communications Management Service (ACM): provides automated handovers between controllers
  • Departure Clearance (DCL): provides automated assistance for requesting and delivering departure clearances to aircraft
  • ATC Clearances Service (ACL): enables operational exchanges over data link (i.e., flight crews send requests and reports; ATC issues clearances, instructions, and notifications)

How will SERA’s CPDLC package integrate with my simulator?

ASTi is the only company to support both stimulated (i.e., hardware) and simulated (i.e., software) avionics solutions. Add CPDLC to almost any simulator on the market with SERA’s flexible integration options.

SERA Cloud Server Diagram

Stimulated Avionics: Integrate with Actual Aircraft Equipment

In a stimulated configuration, a SERA server connects to an ASTi 429 Audio Bridge. This customizable device integrates CPDLC directly into simulator equipment, sending ARINC 741 SATCOM and ARINC 750 VHF protocols over an ARINC 429 bus. Stimulated configurations don't require any reverse engineering or modifications to existing hardware, offering quick and seamless integration.

Simulated Avionics: Integrate with a Software-Simulated Cockpit

In a simulated configuration, the SERA server sends network messages to the host computer, which controls software emulating the MCDU. These messages supply the host with everything it needs to properly recreate CPDLC behavior. The result is a high-fidelity training experience that provides accurate information at just the right moment.