What should a controller do when a pilot indicates they will not accept a SID?

When a pilot indicates they will not accept a Standard Instrument Departure (SID), the appropriate action for a controller is to clear the aircraft via the filed route, if possible. This is important because it allows the aircraft to proceed safely and efficiently without requiring them to refile their flight plan or hold in place, both of which can lead to increased congestion and delays.

Clearing the aircraft via the filed route respects the pilot's request while still facilitating an orderly flow of traffic within the airspace. It’s crucial for air traffic control to maintain safety and efficiency, and by doing this, the controller ensures that the aircraft can still proceed towards its destination without unnecessary alterations to their flight plan.

The other options would be less effective in maintaining efficiency and safety in air traffic management. Instructing the pilot to hold may create unnecessary delays and congestion, while clearing the aircraft direct to the destination could disrupt the traffic flow and create conflicts with other aircraft. Instructing the pilot to refile their flight plan may also cause delays and is not usually necessary if a suitable alternate route is available.