Plain English Meaning

The big number painted at the start of a runway. It tells you roughly which compass direction you'll be pointing when you take off or land on it. A runway pointing east (090 degrees) is called Runway 9. The same strip of pavement, used in the other direction, would be Runway 27.

Full Definition

The number painted on the runway threshold (and shown on charts) that identifies a runway by its magnetic heading rounded to the nearest 10 degrees, with the trailing zero dropped. For parallel runways, a letter is added: L (left), C (center), or R (right). The opposite end of the same runway carries a designation 180 degrees different.

Context Anchor

You see runway designations painted on runway ends, printed on airport diagrams, and referenced in taxi, takeoff, and landing instructions. In closed-runway marking discussions, the designation may be removed or covered so pilots do not the for an open runway.