What information is crucial during a flight plan filed directly with the center?

The most crucial information during a flight plan filed directly with the center includes all items provided by the pilot. When a pilot files a flight plan, they must include comprehensive details such as aircraft identification, departure point, destination, route of flight, alternate airports, estimated times, and any special instructions or needs. This comprehensive set of data ensures that air traffic controllers have all necessary information to provide safe and efficient air traffic service, facilitate situational awareness, and assist in air traffic management throughout the flight. Each detail contributes to understanding the aircraft's intentions and helps in coordinating with other air traffic in the area, making all the filed items significant.