Final answer:
Seamless handoff is preferred for air traffic control when conforming to the appropriate letter of agreement (LOA), providing a smooth transition of aircraft responsibility between controllers.
Step-by-step explanation:
The question focuses on the type of handoff preferred between air traffic controllers. In the context of air traffic control, a handoff refers to the process by which the responsibility for an aircraft is transferred from one controller to another as the aircraft progresses along its flight path. When controllers are conforming to the appropriate letter of agreement (LOA), the preferred method is a seamless handoff. This type of handoff is characterized by a smooth transition with minimal communication required, as all details and contingencies have been previously agreed upon in the LOA, ensuring a safe and efficient transfer of control.