When may you initiate the approach procedure after being radar vectored?

Initiating the approach procedure after being radar vectored is contingent upon receiving explicit clearance from air traffic control. This is crucial because air traffic control is responsible for managing air traffic and ensuring safety during all phases of flight. The clearance ensures that the aircraft is properly sequenced with other traffic and that it meets the necessary criteria for the approach, such as altitude and alignment with the final approach course.

Receiving a clearance is vital for maintaining safe separation from other aircraft, and it confirms that the pilot can proceed with the approach without violating airspace regulations or infringing on the operational patterns of other traffic. Other stages of the approach, such as establishing on the final approach course or reaching an initial approach fix, do not suffice. Without specific clearance from air traffic control, an approach cannot legally or safely commence.