Definition
An RNAV path leg that defines a specific course (a magnetic track) terminating at a designated fix. The aircraft flies the published course until it reaches the fix, at which point the leg ends and the next leg begins.
Plain English
A flight path that says: fly this exact heading until you reach this specific point, then the next instruction takes over.
Context Anchor
Seen in instrument procedures, RNAV routes, and flight-management system leg descriptions.
Derivation
The name describes the leg literally: a 'course' (the track to fly) leading 'to a fix' (the point where the leg ends). The naming follows the ARINC 424 path-terminator system, which labels each leg by what defines it and what ends it. This particular leg is coded 'CF.'
Why Pilots Care
Defines precise segments of instrument approaches so the aircraft follows the published path without deviation until the fix is reached.
Intuition Check
Do not read course as a class of instruction here. In this term, course means the direction or path the airplane is meant to follow over the ground. Do not read fix as repairing something; a fix is a known navigation point.
Example Sentence 1
The approach plate showed a Course-To-A-Fix leg of 270 degrees terminating at the initial approach fix.
Example Sentence 2
After the missed approach the aircraft flew a course to a fix to enter the published holding pattern.