Plain English Meaning

The big numbers painted on each end of a runway. They tell you which compass direction the runway points, using the first two digits of that heading.

Full Definition

Large numerals painted near the threshold of each runway end that identify the runway by its magnetic heading rounded to the nearest ten degrees, with the trailing zero dropped. A runway aligned to a magnetic heading of 273 degrees is marked as 27; the opposite end, aligned 180 degrees the other way, is marked 09.

Context Anchor

Seen on runway pavement, airport diagrams, takeoff briefings, taxi instructions, and radio calls.

Derivation

Runway refers to the surface an aircraft runs along for takeoff and landing. Numbers refers to the directional markers taken from and simplified for easy reading.