At what point should radar be started during the taxi?

The radar should be started in the taxiway because this is the most effective time to begin monitoring and controlling the aircraft's movement on the ground. By activating radar while on the taxiway, ground control can continuously track the aircraft's location, ensuring safe and efficient transitions from the terminal to the runway.

Starting radar at this phase allows for coordination with air traffic control, helping to manage multiple aircraft in close proximity and enhancing safety during ground operations. This proactive approach also facilitates timely communication of any potential obstacles or changes in taxi instructions that might arise, ultimately contributing to smoother operations as the aircraft prepares for takeoff.

Starting radar at any other point would not provide the same degree of situational awareness or safety during ground movement, which is critical in busy airport environments.