Introduction

This article gives an overview of Controller Pilot Data Link Communications (CPDLC). It describes the main principles, the different data link services and the basics of CPDLC operations, including related phraseology. The goal is to provide background information for understanding the safety issues related to this technology.

Definition

Controller Pilot Data Link Communications (CPDLC) is a means of communication between controller and pilot, using data link for ATC communications. (ICAO Doc 4444: PANS-ATM)

Description

CPDLC is a two-way data-link system by which controllers can transmit non urgent 'strategic messages to an aircraft as an alternative to voice communications. The message is displayed on a flight deck visual display.

The CPDLC application provides air-ground data communication for the ATC service. It enables a number of data link services (DLS) that provide for the exchange of communication management and clearance/information/request messages which correspond to voice phraseology employed by air traffic control procedures.