Safety locking device having a rocking hook

A locking device comprising a housing, a first hook cantilevered out on a rocking pin carried by the housing to enable the first hook to rock between an open position and a closed position in which the first hook supports a catch member by a first hooking edge of said first hook, and a retractable locking member disposed to oppose rocking movement of the first hook by a first locking portion of said first hook bearing against said locking member, a second hook adjacent to the first hook, said second hook having a second hooking edge of similar shape to the first hooking edge of said first hook in order to support the catch member, and a link member between the first hook and the second hook, wherein the second hook is maintained in a position close to a position in which the second hook supports the catch member by said second hooking edge when said first hook is in the closed position, so that in the event of a failing of the first hook, the second hook comes into operation for supporting the catch member.