An aircraft passenger seat with dynamic seat back breakover, comprising: a breakover link; a seat back element pivotally-attached to the breakover link; and a breakover mechanism operable for coupling the seat back element to the breakover link in a first operating condition in which the seat back element is movable between an upright position and a reclined position and decoupling the seat back element from the breakover link in a second operating condition to allow the seat back element to move forward relative to the breakover link past the upright position; characterized in that the breakover mechanism comprises an articulating weighted inertia linkage including: a lower link pivotally attached at one end to the breakover link; a pawl link pivotally attached at one end to the breakover link; and an upper link pivotally attached to each of the lower link and the pawl link and free of attachment to the breakover link; wherein in a coupled position corresponding to the first operating condition the articulating weighted inertia linkage prevents relative movement between the seat back element and the breakover link, and in a decoupled position corresponding to the second operating condition the articulating weighted inertia linkage allows relative movement between the seat back element and the breakover link. a breakover link; a seat back element pivotally-attached to the breakover link; and a breakover mechanism operable for coupling the seat back element to the breakover link in a first operating condition in which the seat back element is movable between an upright position and a reclined position and decoupling the seat back element from the breakover link in a second operating condition to allow the seat back element to move forward relative to the breakover link past the upright position; characterized in that the breakover mechanism comprises an articulating weighted inertia linkage including: a lower link pivotally attached at one end to the breakover link; a pawl link pivotally attached at one end to the breakover link; and an upper link pivotally attached to each of the lower link and the pawl link and free of attachment to the breakover link; wherein in a coupled position corresponding to the first operating condition the articulating weighted inertia linkage prevents relative movement between the seat back element and the breakover link, and in a decoupled position corresponding to the second operating condition the articulating weighted inertia linkage allows relative movement between the seat back element and the breakover link. a lower link pivotally attached at one end to the breakover link; a pawl link pivotally attached at one end to the breakover link; and an upper link pivotally attached to each of the lower link and the pawl link and free of attachment to the breakover link; wherein in a coupled position corresponding to the first operating condition the articulating weighted inertia linkage prevents relative movement between the seat back element and the breakover link, and in a decoupled position corresponding to the second operating condition the articulating weighted inertia linkage allows relative movement between the seat back element and the breakover link.