Providing a description of aircraft intent

1. 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, comprising:

obtaining a description of flight intent corresponding to a flight plan spanning the period of flight;

ensuring that the flight intent description is parsed to provide instances of flight intent, each instance of flight intent spanning a flight segment with the flight segments together spanning the period of flight;

converting the parsed flight intent 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 during the flight segment, wherein each instance of flight intent provides a description of the aircraft's motion in at least one degree of freedom of motion thereby closing the associated degree of freedom of motion and/or a description of the aircraft's configuration to close at least one degree of freedom of configuration, and wherein at least some flight segment descriptions contain a parameter range; and

wherein the method further comprises optimising the parametric aircraft intent by determining an optimal value for the parameter of each parameter range.

2. The method of claim 1 , wherein determining the optimal values comprises:

generating initial parameter values thereby forming a model aircraft intent;

calculating a trajectory from the model aircraft intent;

calculating a merit function value for the trajectory using a merit function; and

repeated iterations of amending the parameter values, calculating the resulting trajectory and calculating the resulting merit function value to determine whether the description of aircraft intent is improved, thereby optimising the parameter values by improving the merit function value.

3. The method of claim 2 , wherein one or more flight segment descriptions contain an objective that is relevant to the associated flight segment, and the method further comprises using the one or more objectives to form the merit function.

4. The method of claim 3 , further comprising comparing flight segment descriptions with objectives stored in a database and adding objectives to the flight segment description that are identified as being relevant to the flight segment description.

5. The method of claim 4 , wherein at least some of the objectives are stored in a user preferences model that comprises information describing operational preferences.

6. The method of claim 4 , wherein identifying objectives that are relevant to the flight segment description comprises identifying objectives associated with the aircraft.

7. The method of claim 6 , wherein identifying objectives that are relevant to the flight segment description comprises identifying objectives associated with the aircraft by identifying objectives of the airline operating the aircraft, by identifying objectives pertaining to a phase of flight occurring during the corresponding flight segment, or by identifying objectives pertaining to airspace though which the aircraft will pass during the corresponding flight segment.

8. The method of claim 1 , wherein the description of flight intent obtained includes a description of a set of initial conditions of the aircraft at the start of the period of flight.

9. The method of claim 1 , further comprising obtaining a description of a set of initial conditions of the aircraft at the start of the period of flight and ensuring that the flight intent description and the initial conditions are parsed to provide the instances of flight intent.

10. The method of claim 1 , further comprising calculating a trajectory for the period of flight from the aircraft intent.

11. The method of claim 10 , further comprising causing the aircraft to fly that trajectory or comparing the trajectory with trajectories of other aircraft to identify conflicts.

12. A system for 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, the system comprising:

a processor;

a storage medium comprising instructions thereon, that when executed by said processor, cause the processor to:

obtain a description of flight intent corresponding to a flight plan spanning the period of flight;

ensure that the flight intent description is parsed to provide instances of flight intent, each instance of flight intent spanning a flight segment with the flight segments together spanning the period of flight;

convert the parsed flight intent 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 during the flight segment, wherein each instance of flight intent provides a description of the aircraft's motion in at least one degree of freedom of motion thereby closing the associated degree of freedom of motion and/or a description of the aircraft's configuration to close at least one degree of freedom of configuration, and wherein at least some flight segment descriptions contain a parameter range; and

optimize the parametric aircraft intent by determining an optimal value for the parameter of each parameter range.

13. The system of claim 12 , wherein said storage medium further comprises instructions thereon, that when executed by said processor, cause the processor to:

generate initial parameter values thereby forming a model aircraft intent;

calculate a trajectory from the model aircraft intent;

calculate a merit function value for the trajectory using a merit function; and

repeat iterations of amending the parameter values, calculating the resulting trajectory and calculating the resulting merit function value to determine whether the description of aircraft intent is improved, thereby optimising the parameter values by improving the merit function value.

14. The system of claim 13 , wherein one or more flight segment descriptions contain an objective that is relevant to the associated flight segment, and the system further comprises using the one or more objectives to form the merit function.

15. The system of claim 14 , wherein said storage medium further comprises instructions thereon, that when executed by said processor, cause the processor to:

compare flight segment descriptions with objectives stored in a database; and

add objectives to the flight segment description that are identified as being relevant to the flight segment description.

16. The system of claim 15 , wherein said storage medium further comprises instructions thereon, that when executed by said processor, cause the processor to store at least some of the objectives in a user preferences model that comprises information describing operational preferences.

17. The system of claim 15 , wherein identifying objectives that are relevant to the flight segment description comprises identifying objectives associated with the aircraft.

18. The system of claim 17 , wherein identifying objectives associated with the aircraft comprises identifying an objective of the airline operating the aircraft, identifying an objective pertaining to a phase of flight occurring during the corresponding flight segment, or identifying an objective pertaining to airspace though which the aircraft will pass during the corresponding flight segment, or combinations thereof.

19. An aircraft comprising:

a processor;

a storage medium comprising instructions thereon, that when executed by said processor, cause the processor to:

obtain a description of flight intent corresponding to a flight plan spanning a period of flight;

ensure that the flight intent description is parsed to provide instances of flight intent, each instance of flight intent spanning a flight segment with the flight segments together spanning the period of flight;

convert the parsed flight intent 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 during the flight segment, wherein each instance of flight intent provides a description of the aircraft's motion in at least one degree of freedom of motion thereby closing the associated degree of freedom of motion and/or a description of the aircraft's configuration to close at least one degree of freedom of configuration, and wherein at least some flight segment descriptions contain a parameter range;

optimize the parametric aircraft intent by determining an optimal value for the parameter of each parameter range; and

calculate a trajectory for the aircraft for the period of flight from the aircraft intent.

20. A tangible computer readable storage medium having recorded thereon instructions for 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 that, when executed on a computer, cause the computer to:

obtain a description of flight intent corresponding to a flight plan spanning the period of flight;

ensure that the flight intent description is parsed to provide instances of flight intent, each instance of flight intent spanning a flight segment with the flight segments together spanning the period of flight;

convert the parsed flight intent 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 during the flight segment, wherein each instance of flight intent provides a description of the aircraft's motion in at least one degree of freedom of motion thereby closing the associated degree of freedom of motion and/or a description of the aircraft's configuration to close at least one degree of freedom of configuration, and wherein at least some flight segment descriptions contain a parameter range; and optimize the parametric aircraft intent by determining an optimal value for the parameter of each parameter range.