Definition
A two-digit number painted on each end of a runway that indicates the runway's magnetic heading rounded to the nearest ten degrees, with the final zero dropped. A runway aligned to a magnetic heading of 270 degrees is marked '27'; one aligned to 090 degrees is marked '09'. Where parallel runways exist, a letter is added after the number (L for left, C for center, R for right) to distinguish them.
Plain English
The big number painted at the start of a runway. It tells you which compass direction the runway points, using the first two digits of its magnetic heading.
Context Anchor
Seen painted in large numbers on the runway surface, printed on airport diagrams, and used in taxi, takeoff, landing, and radio instructions.
Why Pilots Care
It prevents alignment with the wrong runway and ensures the aircraft departs or arrives in the intended direction.
Intuition Check
Do not read the runway number as an arbitrary label or street address. It is a shortened compass direction based on magnetic direction, rounded to the nearest 10 degrees.
Example Sentence 1
Cleared to land Runway 27, the pilot confirmed the heading indicator read approximately 270 before turning final.
Example Sentence 2
Winds had shifted, so the tower changed the active runway to number 27.