A departure clearance is effective upon termination of the call. Which event terminates the call?

• A. The student gives their initials
• B. The controller ends the transmission
• C. The aircraft leaves the sector boundary
• D. The handoff is acknowledged

Answer: (A)

The active departure clearance is established only when the two-way exchange is finished and the readback is accepted. In this scenario, the signal that the exchange is complete is the student giving their initials, which indicates they have correctly read back the clearance and accept it. With that sign-off, the controller can consider the clearance in effect and terminate the call.

Ending the controller’s transmission by itself doesn’t prove the readback is complete, and the aircraft leaving the sector boundary or a handoff acknowledgment are separate actions that don’t mark the termination of the current clearance conversation.