Which traffic management initiative spaces arrivals into a time window at the approach?

• A. Mile-in-trail
• B. Traffic reroutes
• C. Ground delay
• D. Metering

Answer: (D)

Metering is the process of regulating the flow of arriving aircraft so they cross a defined point and enter the approach within a specific time window. By assigning target times of arrival and sometimes adjusting speed or issuing brief holds, controllers space arrivals to match runway capacity and prevent congestion or excessive holds. The other methods operate differently—mile-in-trail uses fixed distance gaps, rerouting shifts traffic to alternate paths to relieve load, and ground delay spaces out departures or arrivals on the ground rather than managing the approach flow.