In radar operations, arrivals can be separated from departures by a minimum of 2 miles when the separation will increase to 3 mils within 1 minute after takeoff. The 2-mile minimum is determined when which event occurs?

• A. Arriving passes initial approach fix
• B. Weather conditions are stabilized
• C. Departing begins takeoff roll
• D. Controller's instruction

Answer: (C)

The concept being tested is how mixed arrivals and departures are separated using a time‑based, performance‑dependent standard. A 2‑mile minimum between an arrival and a departing aircraft can be used if that separation is expected to grow to 3 miles within one minute after takeoff. The moment this 2‑mile minimum is established is when the departure begins takeoff roll, because that is when the aircraft actually starts its climbaway and the 1‑minute window for achieving the 3‑mile separation starts. Before takeoff, the departure isn’t moving, so the 2‑mile allowance isn’t determined yet. Weather, initial approach timing, or the controller’s clearance instruction don’t set this initial limit; the key event is the start of takeoff roll.