Definition
The painted line of white dashes running down the middle of a runway, marking its lengthwise center and serving as the primary visual reference for aligning the airplane during takeoff, landing, and rollout.
Plain English
The dashed white line painted down the middle of the runway. Pilots use it to keep the airplane straight and centered while taking off, landing, and rolling out.
Context Anchor
Seen during approach, landing, takeoff, and especially after landing while the airplane is slowing down on the runway.
Why Pilots Care
Tracking the centerline keeps the airplane equidistant from both runway edges, giving maximum margin if a tire blows, a gust hits, or directional control momentarily slips. Drifting off the centerline reduces that safety buffer and can lead to a runway excursion.
Intuition Check
Do not think of the runway centerline as just a painted decoration. In flying, it is an alignment reference the pilot actively uses to keep the airplane tracking straight down the runway.
Example Sentence 1
After touchdown, he kept the nosewheel tracking straight down the runway centerline as the airplane decelerated.
Example Sentence 2
During the takeoff roll the airplane tracked straight along the runway centerline until rotation.