Definition
A reference line, real or imaginary, running lengthwise through the exact middle of an object or surface. In aviation it commonly refers to the painted stripe down the middle of a runway or taxiway, or to the longitudinal axis of an aircraft running nose to tail through its center of symmetry.
Plain English
The line running straight down the middle of something — the middle of the runway, the middle of the taxiway, or the imaginary line straight down the middle of the aircraft from nose to tail.
Context Anchor
Seen on runway and taxiway markings, and heard in instructions such as lining up on the runway center line before takeoff.
Why Pilots Care
Staying on the center line keeps the aircraft safely within the paved surface and properly aligned with the intended path.
Analogy
It works like the middle stripe of a road lane: it gives you a clear reference for where the vehicle should be pointed and positioned.
Intuition Check
Do not assume Center Line means any line near the middle. In aviation, it means the specific middle reference line used for aircraft alignment on a runway, taxiway, or similar surface.
Example Sentence 1
After lining up on the runway, the pilot held the nosewheel on the center line as he advanced the throttle for takeoff.
Example Sentence 2
During the landing rollout, the center line lights helped maintain alignment in low visibility.