an energy absorbing device for carrying a passenger seat ; the device comprises a base fixed to a vehicle ; a member displaceable from base ; at least one energy - absorbing arrangement interconnecting base and displaceable member . the energy - absorbing arrangement comprises a plastically deformable absorbing element in response to stresses greater than a predetermined threshold stress . in some embodiments the plastically deformable absorbing element is a helically configured ribbon having spaced - apart ribbon laps . in other embodiments the plastically deformable absorbing element is compressible , and / or extendable . a method of attenuating the acceleration applied to a passenger due to impact is disclosed ; the method comprises steps of : providing an energy absorbing device fixedly attaching the base to the vehicle ; fixedly attaching the passenger seat to the base ; accidently applying the impact to the vehicle ; displacing the displaceable member relative to the base ; attenuating the effect of the impact on the passenger .