Shoulder belt-type aircraft seat comprising an energy absorbing device

The energy absorbing device includes a casing and a shaft which are rotatably interconnected via disc frames (12) comprising at least one arcuate area (13) of plastically deformable material, opposing the rotation of the shaft with respect to the casing in a first direction, corresponding to a forward-leaning movement of the seat backrest. The casing and shaft are also interconnected via a ratchet wheel (16) allowing the rotation of the shaft with respect to the casing in the direction opposite to the first direction, corresponding to a backward-leaning direction of the seat backrest, without acting on the disc frames. The rotation of the shaft with respect to the casing in the first direction is subjected to the reaction of the disc frames.