A B737 is departing Runway 28R. A Cherokee is holding short of Runway 34, requesting takeoff. When is the earliest the Cherokee may depart?

• A. As soon as B737 takes off
• B. As soon as B737 passes the threshold
• C. As soon as B737 passes the intersection
• D. Once B737 reaches climb altitude

Answer: (C)

The correct timing for the Cherokee's departure is determined by the B737's proximity to its takeoff path and the active runway operations. In this scenario, the B737 is departing from Runway 28R, which does not intersect with Runway 34, where the Cherokee is holding short. However, the critical factor is ensuring safe separation between the two aircraft.

The earliest the Cherokee may depart is once the B737 has passed the intersection with Runway 34, which is the point where the potential conflict exists due to the B737’s flight path. By waiting until the B737 passes this intersection, air traffic control ensures that the Cherokee can take off without risking any potential conflicts with the B737's climb or departure path.

Other timings, like allowing the Cherokee to depart as soon as the B737 takes off or as soon as it passes the threshold, do not account for the safe separation needed when an aircraft is still in the process of climbing away from its departure runway. Similarly, waiting until the B737 reaches climb altitude is unnecessary, as the Cherokee can safely depart once the B737 has moved beyond the intersection and posed no threat to its flight path. Thus, passing the intersection is the critical point that allows for a safe and