What should be done immediately following the handoff of an aircraft?

The immediate step following the handoff of an aircraft is to transfer radio communications to ensure the new controller can establish contact with the aircraft promptly. This step is crucial for maintaining continuous communication and ensuring that all relevant information is shared seamlessly between air traffic control sectors. Once the handoff is performed, the new controller must take over responsibilities for managing the aircraft's flight path, which hinges on effective communication. Establishing this contact allows for immediate updates on the aircraft's status, intentions, and any instructions that need to be conveyed to the pilot, enhancing safety and operational efficiency.

The other options, while important in their own right, are not the immediate priority post-handoff. Updating a flight plan may be necessary as the aircraft proceeds, but it comes after ensuring communication is established. Contacting ground control is not relevant in this context unless the aircraft is landing and transitioning to ground operations, which would happen later in the process. Notifying emergency services would only be pertinent in a situation where an emergency is declared, which should not be a routine action following a handoff.