The present disclosure provides a computer-implemented method of generating a description of aircraft intent expressed in a formal language that provides an unambiguous description of an aircraft's intended motion and configuration during a period of flight. A flight intent description is parsed to provide instances of flight intent that span a flight segment, the flight segments together spanning the period of flight. The parsed flight intent is converted into parametric aircraft intent by generating an associated flight segment description for each flight segment that comprises instances of flight intent to close all associated degrees of freedom of motion and of configuration of the aircraft. At least some flight segment descriptions contain a parameter range, and the method further comprises optimizing the parametric aircraft intent by determining an optimal value for the parameter of each parameter range.