Seat for powered aircraft having a leg assembly comprising three points for anchoring to the floor of the aircraft

The seat has a base that is arranged for carrying a bucket seat through an energy absorbing unit. The base is arranged with an establishment frame (5) on an installation plane (P1) on the base. The establishment frame is provided with a supporting frame on the bucket seat and is provided with an anchor unit (6). A set of anchor points (10-12) is arranged for defining an isostatic plane (P2), and the establishment frame is able to accompany a deformation of the installation plane by tilting the isostatic plane.