Energy absorber for anti-crash seat and an anti-crash seat with such an absorber.

An energy absorber (100) for limiting an acceleration force undergone by a heavy body, such as an occupant of a seat subjected to acceleration during an aircraft crash, comprises a take-up drum (10) mounted for rotation about a shaft (13) around which a traction line (11) is wound. The shaft is mechanically coupled to a brake (20) which immobilizes the shaft (13) in rotation when a torque applied to the shaft by the traction line is less than the maximum brake torque that can be generated by the brake and which, when the shaft (13) is rotating, generates a substantially constant torque equal to the maximum brake torque. A control member (40) acting on the brake (20) makes it possible to modify the value of the maximum brake torque and thus to adapt the energy absorber to the mass of the heavy body in order to maintain an acceleration undergone at a desired value for different masses.