Method and device for predicting the stopping position of an aircraft whilst landing

1. A method for predicting a stopping position of an aircraft during an approach phase while the aircraft is at a current height and descending towards a runway following a current approach path at a current approach speed, said aircraft passing, with a reference speed, through a reference approach position disposed at a reference height above a proximal threshold of said runway so that a reference stopping position on the runway is distant from said proximal threshold by a reference distance that can be determined by calculations of the aircraft's performance, the method comprising:

when said current height of said aircraft is greater than said reference height,

calculating, using a computing device on board the aircraft, a variation of total energy of said aircraft between a point of said current approach path which has the current height and a particular point of said current approach path which has the reference height and through which said aircraft passes at the reference speed;

determining, using said computing device, from said variation of the total energy, the horizontal position of said particular point; and

adding, using said computing device, said reference distance to said horizontal position of said particular point.

2. The method as claimed in claim 1 , wherein said horizontal position of said particular point of the current approach path is determined from the current horizontal position, the weight, the current approach speed and the current height of the aircraft, as well as from the acceleration of gravity, said reference height, said reference speed and a coefficient, determined from equations of flight mechanics of said aircraft and representing a maximum loss of total energy of the latter as a function of horizontal distance traveled by said aircraft on the ground.

3. The method as claimed in claim 1 , wherein, when said aircraft has passed, whilst descending, said particular point of the current approach path, said stopping position of said aircraft is predicted by calculating the position of the point at which said aircraft touches the runway and by adding to this calculated position a braking distance, known from standard performance figures of said aircraft.

4. The method as claimed in claim 3 , wherein the position of the point at which the aircraft touches the runway is calculated from the height, the longitudinal speed and the vertical speed of said aircraft.

5. The method as claimed in claim 1 , wherein it is checked if the predicted stopping position is on said runway and the result of this check is displayed close to a pilot of the aircraft.

6. A device for the implementation of the method as claimed in claim 1 , wherein the device comprises:

the computing device:

receiving at least information relating to the current horizontal position, the current weight, the current approach speed, the current height of the aircraft, as well as a coefficient representing total energy loss as a function of a variation of said current horizontal position of the aircraft, the acceleration of gravity, the reference height and the reference speed attached to said reference approach position and said reference distance; and

calculating a predicted stopping position along an axis of said runway; and

a comparator that verifies the location of said predicted stopping position with respect to said runway.

7. The device as claimed in claim 6 , further comprising a prediction section that predicts, when said aircraft has passed, whilst descending, said particular point of the current approach path, said stopping position of said aircraft by calculating the position of the point at which said aircraft touches the runway and by adding to the calculated position a braking distance, known from standard performance figures of said aircraft, wherein said computing device furthermore receives information concerning the horizontal speed and the vertical speed of said aircraft, as well as said braking distance.

8. The device as claimed in claim 6 , wherein said comparator controls a usual piloting screen on which is displayed a representation of said runway and a symbol, superimposed on said representation, indicating the evolution of said predicted stopping position during the landing.