Method and device for determining a reliable position of an aircraft

A method for determining a reliable position of an aircraft, according to which method the following operations are carried out:

• a) at least three first position values which each relate to the current position of the aircraft are produced, each of these three first position values being produced on the basis of information arising respectively from onboard receivers (4) which are associated with a satellite positioning system, and for each position value a probability space (C1, C2) is determined, each probability space (C1, C2) being centered around the corresponding position value (C1, P2) and defining the volume in which, with a probability greater than a predetermined threshold, the actual position of the aircraft is situated;
• b) consistency tests are implemented to verify whether these first position values are mutually consistent, these consistency tests making it possible to declare for each of said first position values whether or not it is valid in terms of reliability, said consistency tests consisting in testing position values pairwise, each consistency test consisting in determining a threshold value which depends on the radii (HPL1, HPL2) of the probability spaces (C1, C2) associated with the two tested position values (P1, P2) and in comparing the distance between these two position values with said threshold value so that, if said distance is greater than this threshold value, there exists a reliability problem;
• c) at least two second position values which each relate to the current position of the aircraft and which correspond to hybrid position values are calculated with the aid of said first position values and with the aid of inertial information;
• d) consistency tests are implemented to verify whether said second position values are mutually consistent, these consistency tests making it possible to declare for each of said second position values whether or not it is valid in terms of reliability;
• and
• e) on the basis of at least certain of said first and second position values which have been declared valid by means of the consistency tests implemented in said operations b) and d), a reliable current position of the aircraft is determined with the aid of a consolidation scheme.

A device for determining a reliable position of an aircraft, said device comprising:

• a system (2) configured to produce at least three first position values which each relate to the current position of the aircraft, said system (2) comprising receivers (4) carried onboard which are associated with a satellite positioning system and which are, each, configured to provide information making it possible to produce a first position value, a probability space (C1, C2) being determined for each position value, each probability space (C1, C2) being centered around the corresponding position value (P1, P2) and defining the volume in which, with a probability greater than a predetermined threshold, the actual position of the aircraft is situated;
• a first implementation section (8) that implements consistency tests that (i) enable verification of whether these first position values are mutually consistent and (ii) make it possible to declare for each of said first position values whether or not it is valid in terms of reliability, said consistency tests consisting in testing position values pairwise, each consistency test consisting in determining a threshold value which depends on the radii (HPL1, HPL2) of the probability spaces (C1, C2) associated with the two tested position values (P1, P2) and in comparing the distance between these two position values with said threshold value so that, if said distance is greater than this threshold value, there exists a reliability problem;
• a calculation section (10) that calculates, with the aid of said first position values and with the aid of inertial information, at least two second position values which each relate to the current position of the aircraft and which correspond to hybrid position values;
• a second implementation section (16) that implements consistency tests that (i) enable verification of whether said second position values are mutually consistent and (ii) make it possible to declare for each of said second position values whether or not it is valid in terms of reliability;
• and
• a determination section (18) that determines, on the basis of at least certain of said first and second position values which have been declared valid by said first and second implementation sections (8, 16), a reliable current position of the aircraft, by implementing a consolidation scheme.