Definition
An indication on a navigation instrument that the aircraft is located on the selected course or radial, with no left or right deviation displayed.
Plain English
A signal from your navigation instrument telling you that you are flying directly along the path you chose, not off to one side or the other.
Context Anchor
Seen when using a navigation instrument to track a course, such as when the course needle or display shows the aircraft is centered on the selected path.
Derivation
“Course” comes from older words meaning a path or line of movement. “Indication” means something that points out or shows information. Together, the phrase means a display that shows the aircraft is on the intended path.
Why Pilots Care
Confirms accurate tracking of a published route or approach centerline, reducing the risk of course deviation in instrument conditions.
Intuition Check
On-course does not necessarily mean the airplane’s nose is pointed exactly along the course. With wind, the pilot may need to point slightly into the wind while still getting an on-course indication.
Example Sentence 1
Once the needle centered, the pilot confirmed an on-course indication and continued tracking the airway.
Example Sentence 2
During the ILS approach, the crew waited for a steady on-course indication before beginning descent.