What is assigned when a Standard Instrument Departure (SID) is not established for the departure route or the pilot indicates a preference?

When a Standard Instrument Departure (SID) is not established for a departure route or if a pilot indicates a preference for a specific route, the appropriate action is to assign a proposed departure route (PDR) for the filed route. This ensures that the flight has a clear and defined path to follow after departure, which is crucial for maintaining safety and efficiency in air traffic operations.

The PDR takes into account both the filed route by the pilot and any air traffic control (ATC) considerations, providing the necessary guidance for the pilot to follow after takeoff. This assignment helps maintain an organized flow of air traffic, especially in busy airspace or when standard routes are not available.

Establishing a PDR also allows pilots to follow their preferred routing when SIDs aren't in play, which can enhance their situational awareness and confidence during the initial phase of flight. This adaptability in routing is vital for responding to varying traffic conditions and operational needs of the flight.

Other options such as standard routing, flight following, and clearance void times serve different purposes in air traffic control processes, but in this context, they do not effectively address the scenario presented regarding the absence of a SID or pilot preference for routing.