Which clearance procedures can ATC issue without prior pilot request?

Air Traffic Control (ATC) has the authority to issue certain clearances without needing a prior request from the pilot. In the context of departure and approach procedures, the key elements involved include Standard Instrument Departures (SIDs), Standard Terminal Arrival Routes (STARs), and visual approaches.

SIDs are pre-defined routes that guide aircraft from the airport to points in the airspace, designed to ensure efficient traffic flow while minimizing conflicts with other air traffic. When pilots are not specifically requesting a SID, ATC can still assign one to ensure the orderly movement of aircraft.

Similarly, STARs serve as structured routes that streamline the arrival of aircraft into busy terminal areas. ATC has the discretion to assign STARs based on traffic management and operational efficiency without needing to wait for a pilot's request.

Visual approaches, while less structured, allow ATC to guide a pilot in for landing using visual references rather than following standard instrument procedures. ATC can initiate a visual approach based on traffic and weather conditions without waiting for the pilot to ask for it.

In contrast, the other options mentioned focus on clearances that are typically based on pilot requests or might not offer the same breadth of ATC discretion seen with SIDs, STARs, and visual approaches,