Definition
In ATC data communications, the established logical link between an aircraft's avionics and an air traffic control facility that enables digital messages (such as CPDLC clearances and instructions) to be exchanged. A connection must be active before controller-pilot data link communications can take place, and it can be initiated, transferred between facilities, or terminated.
Plain English
A live digital link between your aircraft and ATC that lets you send and receive text-based messages instead of (or alongside) talking on the radio. If the link isn't established, the data messages can't go through.
Context Anchor
Seen in data-link communication procedures, especially when an aircraft logs on to communicate digitally with air traffic control.
Derivation
Connection comes from the Latin idea of “joining together.” That helps here because the word does not mean a physical cable or a passenger transfer; it means two communication systems have been joined electronically.
Why Pilots Care
Recognizing a connection lets you accept a clearance change, stay on an approved route, and avoid deviating into uncontrolled or restricted airspace.
Intuition Check
Do not read connection here as a passenger changing flights or as a physical plug. In this FAA context, it means an active digital communication link between the aircraft and the ground system.
Example Sentence 1
After logging on, the crew confirmed the CPDLC connection with Oakland Center was active before requesting a route change via Data Comm.
Example Sentence 2
On the enroute chart the pilot located the connection between the two airways and confirmed it matched the filed route.