Which of the following is a traffic management initiative used by the FAA to manage capacity and delay?

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

Answer: (A)

Mile-in-trail is a traffic management initiative that preserves a steady flow of aircraft by enforcing a fixed spacing—about one mile—between planes along certain routes. By controlling how closely aircraft follow each other, the FAA can smooth throughput, prevent bottlenecks from building up, and manage overall capacity and delays in en route airspace. Controllers can adjust speed or sequencing to maintain the required spacing, which helps absorb fluctuations in demand without letting delays pile up. This is different from ground-based measures like ground delays or ground stops, which affect airport departures or arrivals on the surface, and from rerouting, which changes the path rather than the spacing along a corridor. Mile-in-trail directly targets the flow of traffic in the air to optimize capacity.