What must be included in a flight plan as per FAA regulations?

The inclusion of a route, destination, and estimated time in a flight plan is essential as per FAA regulations. A flight plan serves as a critical communication tool between pilots and air traffic control, providing necessary information about the intended flight. The route details allow air traffic controllers to manage air traffic efficiently by understanding the planned path of the aircraft, while the destination informs them where the aircraft is headed. The estimated time of departure and arrival gives controllers a timeframe for managing potential congestion in the airspace and coordinating with other flights. This information enhances safety and ensures that all necessary preparations are in place for the flight's progression.

Other choices do not meet the comprehensive requirements laid out by FAA regulations for a flight plan. The pilot's name and address, although important for identification, do not provide enough detail about the flight itself. Aircraft registration number and maintenance history are relevant to the aircraft's airworthiness but are not required components of a flight plan. Weather conditions and passenger details are important for flight safety and planning, but they are not mandatory inclusions in a flight plan as stipulated by the FAA. Thus, the most complete and relevant answer is the one that includes route, destination, and estimated time.