Definition
A two-way communication system that allows air traffic controllers and pilots to exchange routine messages as text rather than by voice over the radio. Messages are sent via a digital data link between ground ATC computers and the aircraft's flight management system or display unit, and typically include items such as clearances, route changes, altitude assignments, frequency changes, and pilot requests.
Plain English
A way for controllers and pilots to send each other short text messages instead of talking on the radio. The pilot reads the message on a screen in the cockpit and replies by selecting a response, similar in feel to a structured text exchange.
Context Anchor
Seen in aircraft and airspace equipped for digital messaging with air traffic control, especially where radio use is busy or long-range communication is needed.
Derivation
The name describes the system literally: communications between the controller and the pilot, carried over a data link rather than voice. 'Data link' simply means a digital channel that carries information between two points — in this case, between an ATC ground system and the aircraft.
Why Pilots Care
It reduces frequency congestion, prevents misheard clearances, and provides a written record of instructions that improves safety and efficiency.
Analogy
It is a little like text messaging with air traffic control, but the messages are standardized aviation messages, not casual conversation.
Grounding Statement
A controller can send a clearance to the cockpit display, and the crew can send back an accepted or rejected response.
Intuition Check
Do not assume this means the controller is flying the airplane by computer. It means the controller and pilot are communicating through written digital messages.
Example Sentence 1
After crossing the oceanic entry point, the crew logged on to CPDLC and received their next altitude clearance as a text message on the cockpit display.
Example Sentence 2
Controller–Pilot Data Link Communications allowed the controller to send a direct clearance that appeared on the flight deck display.