Method for monitoring the integrity of an aircraft position computed on board

1. A method for monitoring the integrity of an aircraft position channel on board said aircraft comprising:

using a plurality of redundant primary channels, each redundant primary channel computing, during a primary computing cycle, a primary position (PosCri) of the aircraft;

establishing, within the electronic control devices on-board in the aircraft, pairs of computing channels by associating, with each primary computing channel, a dissimilar computing channel, each dissimilar computing channel computing, during a dissimilar computing cycle, a dissimilar position (PosDis) of the aircraft;

computing, for each computing channel pair established, a distance (E 1 ; E 2 ; E 3 ) between the primary position and the dissimilar position respectively computed by the primary computing channel and the dissimilar computing channel of the computing channel pair considered;

comparing each distance computed to an alarm threshold;

sending alarm information when at least one computed distance is greater than the alarm threshold.

2. The method according to claim 1 , wherein said plurality of redundant primary channels corresponds to at least one first, one second and one third redundant channel.

3. The method according to claim 1 , wherein alarm information is only sent when the computed distance is greater than the alarm threshold for at least two pairs of established computing channels simultaneously.

4. The method according to claim 1 , wherein alarm information is only sent when the computed distance is greater than the alarm threshold for several consecutive computing cycles.

5. The method according to claim 1 , wherein the number of consecutive cycles, presenting a computed distance greater than the alarm threshold, from which the alarm information is sent, is equal to three.

6. The method according to claim 1 , wherein the computed primary position is comprised of a first component and a second component, respectively corresponding to a horizontal component (PosCriH) for the computed primary position and to a vertical component (PosCriV) for the computed primary position, and in that the computed dissimilar position is comprised of a first component and a second component, respectively corresponding to a horizontal component (PosDisH) for the computed dissimilar position and to a vertical component (PosDisV) for the computed dissimilar position, the computed distances being computed on the one hand between horizontal components and on the other hand between vertical components.

7. The method according to claim 6 , wherein the method further comprises for each computed distance and prior to the step of comparing the computed distance considered and the alarm threshold, modifying the value of the computed distance considered to make the value lower than the alarm threshold when the vertical component of the computed dissimilar position, reduced by a value of the vertical integrity measurement for the dissimilar position (VPLDis), is greater than the vertical component of the computed primary position.

8. The method according to claim 6 , wherein the method further comprises, for each computed distance and prior to the step of comparing each computed distance and the alarm threshold, modifying the value of the computed distance to make the value lower than the alarm threshold when the vertical component of the computed dissimilar position, reduced by a value of the vertical integrity measurement for the dissimilar position (VPLDis), is greater than a lower bound equal to the vertical component of the computed primary position reduced by a value of the vertical integrity measurement for the primary position (VPLCri).

9. The method according to claim 6 , wherein the method further comprises, prior to the step comparing each computed distance and the alarm threshold, modifying the value of a computed distance to make the value lower than the alarm threshold when a limit value, equal to the sum of a measurement of the horizontal integrity of the dissimilar position and a value of a distance between the horizontal component of the computed primary position and the horizontal component of the computed dissimilar position, is less than a measurement of the horizontal integrity of the primary position.

10. The method according to claim 1 , wherein the alarm threshold comprises a horizontal reference to which the distances between horizontal components are compared, and a vertical reference to which the distances between vertical components are compared.

11. The method according to claim 1 , wherein the primary computed position is a position hybridized with military GPS, and in that the dissimilar position is a position hybridized with civilian GPS.

12. The method according to claim 1 , wherein the dissimilar channels are redundant.

13. An aircraft comprising a device implementing the method according to claim 1 .

14. A device for computing a position of an aircraft integrated with said aircraft, comprising:

a multiplicity of redundant primary computing channels, able to compute, during a primary computing cycle, a primary aircraft position (PosCri);

a multiplicity of dissimilar computing channels associated with each primary computing channel in such a way as to form pairs of computing channels, each dissimilar computing channel being able to compute, during a dissimilar computing cycle, a dissimilar position (PosDis) of the aircraft;

a computer configured to compute, for each computing channel pair established, a distance (E 1 ; E 2 ; E 3 ) between the primary position and the dissimilar position respectively computed by the primary computing channel and the dissimilar computing channel of the computing channel pair considered;

wherein the computer is further configured to compare each distance computed to an alarm threshold; and

the computer is still further configured to send alarm information when at least one computed distance is greater than the alarm threshold.

15. The device according to claim 14 , wherein the device comprises at least one first, one second and one third primary computing redundant channels and at least one first, one second and one third dissimilar computing channels respectively associated with the first, second and third primary computing channels in such a way as to respectively form at least one first, one second and one third computing channel pairs.

16. An aircraft comprising a position computing device according to claim 14 .