Definition
Used by ATC to indicate that an aircraft is established directly on the centerline of the assigned course or route. Also used by ATC to advise a pilot making a radar approach that the aircraft's position relative to the final approach course (lateral position only) is satisfactory.
Plain English
An ATC term meaning the aircraft is lined up correctly side-to-side on the route or approach path it is supposed to be flying.
Context Anchor
Used in navigation and ATC communication when confirming that an aircraft is following the correct path.
Derivation
Course comes from a Latin word meaning “a running” or “a path followed.” That helps here because an aircraft’s course is the path it is meant to follow over the ground.
Why Pilots Care
Staying on course ensures obstacle clearance, accurate arrival timing, and a stabilized approach, especially in low visibility.
Analogy
Like driving exactly between the lane lines on a straight highway instead of just heading generally toward your exit.
Intuition Check
Do not read “on course” as just “things are going well.” In aviation, it specifically means the aircraft is aligned with and following the correct path.
Example Sentence 1
After turning to the assigned heading, the controller advised, 'Cessna Three Four Lima, on course, resume own navigation.'
Example Sentence 2
ATC instructed the pilot to turn five degrees right to return to course after a wind drift.