Definition

RUNWAY IN USE/ACTIVE RUNWAY/DUTY RUNWAY - Any runway or runways currently being used for takeoff or landing. When multiple runways are used, they are all considered active runways. In the metering sense, a selectable adapted item which specifies the landing runway configuration or direction of traffic flow. The adapted optimum flight plan from each transition fix to the vertex is determined by the runway configuration for arrival metering processing purposes.

Source: US FAA JO 7110.65 ATC

Description

The term "runway-in-use" is used to indicate the runway or runways that, at a particular time, are considered by the aerodrome control tower to be the most suitable for use by the types of aircraft expected to land or take off at the aerodrome.

More than one runway may be designated as runway-in-use. This is usually called "runway configuration". Examples include: