A system for establishing an operational flight plan includes a basic flight data acquisition unit for acquiring basic flight data from an external flight plan development system, the basic flight data comprising at least one theoretical fuel weight to be loaded into the aircraft. The system also includes an aircraft actual operational specifications acquisition unit for acquiring actual operational specifications of the aircraft, the actual operational specifications including an airplane context; a proposed flight data calculating unit for calculating proposed flight data including at least one proposed weight of fuel corresponding to the theoretical weight, calculated based on actual operational specifications of the aircraft and a specified trajectory of the aircraft; and a viewer, and a display manager capable of displaying a proposed flight data display window including the proposed fuel weight.