Controller Pilot Data Link Communication (CPDLC) manufactured by TESBL Aerospace 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.

The controllers are provided with the capability to issue ATC clearances which includes level assignments, lateral deviations/vectoring, speed assignments, radio frequency assignments, and various requests for information.

The pilots are provided with the capability to respond to messages, to request/receive clearances and information, and to report information. A “free text” capability is also provided to exchange information not conforming to defined formats.

The CPDLC system indicates the location of an aircraft in flight based on an ADS report from the pilot and CPDLC messages on a screen.