On a transfer flight, what piece of information regarding the patient is necessary?

The piece of information necessary regarding the patient during a transfer flight is the patient's pickup department. This detail is critical for ensuring that the air ambulance crew knows exactly where to collect the patient. Knowing the pickup department facilitates a smooth and efficient transfer process, allowing the flight crew to coordinate with hospital staff for timely patient handover and ensure that necessary resources and personnel are available at the specified location.

While the other options, such as the patient's emergency contact, insurance information, and previous treatment history, can be important for overall patient care and administration, they do not directly influence the logistics of the transfer flight itself. Focusing on the pickup department aligns with the operational needs of the air evacuation process, emphasizing coordination and safety in transporting the patient.