A seat attached to a vehicle structure by at least four attachment points comprises, on at least one of the attachments an extendable connecting element (40) which transmits load between the main structure (11) of the seat and the structure of the vehicle, the extendable connecting element (40) including: —a first position in which a structure pin (62), which attaches the extendable connecting element (40) to the structure of the vehicle, is in a position close to a seat pin (64) that attaches the extendable connecting element (40) to the main structure (11) of the seat; a second position in which the structure pin (62) is in a position away from the seat pin (64) and in which the extendable connecting element (40) is able to transmit load between the structure pin (62) and the seat pin (64).