Abstract: A convertible seat with variable dimensions for public transportation, comprises back lengthening elements, association and positioning device to fit the lengthening elements on either side of the back opposite to the side-edges, and to position the lengthening elements between a retracted position corresponding to a position of minimum seat dimensions along a dimensional axis and a stretched position corresponding to a position of maximum seat dimensions along the dimensional axis.

Abstract: A structure comprising a plurality of adjacent seats for a public passenger vehicle, in particular an airliner, the structure being convertible and of variable size along a sliding axis (100), and comprising:a fixed portion (2) comprising at least two transverse underframes (4) that are spaced apart from each other, fixed to the floor of the passenger cabin, and rigidly connected to one another by longitudinal underframe elements (5) having an axis that is generally parallel to the sliding axis;at least one moving portion (3) that is movable relative to the fixed portion between two extreme positions, namely a maximum-size first position and a minimum-size second position, the moving portion (3) including an end transverse seat side member (6) rigidly associated with longitudinal support elements (7), and intermediate transverse seat side members (8) parallel to the end transverse seat side member (6) and associated with the longitudinal support elements (6), and serving to mount seat backs and arms; andlocki