Method of computing lateral trajectories

A system for computing trajectory of an aircraft between a departure point (Pd) and an arrival point (Pa), comprising a flight management computer and lines of non-transitory computer code intended to be executed on the said computer, the said lines of computer code comprising instructions for executing a computing of an aircraft trajectory for an optimal flight geometry between a departure point (Pd) and an arrival point (Pa), said instructions comprising:

• loading in the flight management computer the departure point (Pd) and a departure angle (Ad) with a vertex at the departure point, separating a first reference straight line (Refd) and a departure straight line (Dd) oriented according to the aircraft travel direction at the departure point,
• determining with the flight management computer two waypoints (P0L, P0R) of respectively left and right type on the basis of the departure point (Pd),
• loading in the flight management computer the arrival point (Pa) and an arrival angle (Aa) with a vertex at the arrival point, separating a second reference straight line (Refa) and an arrival straight line (Da) oriented according to the aircraft travel direction at the arrival point,
• loading in the flight management computer a departure speed (Vd) and an arrival speed (Va) of the aircraft,
• determining with the flight management computer two departure circles of respectively left (CdL) and right (CdR) type, which are tangent to the oriented departure straight line (Dd) respectively on the left and on the right, and passing respectively through the waypoint of left type (P0L) and through waypoint of right type (P0R), the said circles exhibiting a departure radius (Rd) determined on the basis of the departure speed (Vd),
• determining with the flight management computer two arrival circles of respectively left and right type (CaL, CaR) which are tangent to the oriented arrival straight line (Da) respectively on its left and on its right and passing through the arrival point (Pa), the said circles exhibiting an arrival radius (Ra) determined on the basis of the arrival speed,
• determining with the flight management computer a plurality of continuous geometric lateral trajectories comprising an initial portion (Pinit) comprising a portion of a departure circle, a final portion (Pfinal) equal to a portion of an arrival circle, and an intermediate portion (Pint), such that the aircraft travel direction on the initial portion and the final portion coincides with the direction respectively of the oriented departure straight line (Dd) at the departure point (Pd) and the oriented arrival straight line (Da) at the arrival point (Pa),
• computing with the flight management computer a plurality of predicted trajectories by using the equations of flight mechanics for the aircraft on the basis of the plurality of geometric trajectories as a function of a global state of the aircraft, and
• communicating with the flight management computer at least one of the plurality of predicted trajectories to at least one of the following:
• an autopilot system to control the flight of the aircraft and a man-machine interface for display to the pilot for control of the flight of the aircraft.