A locking system comprising a handle mounted such that it can rotate about an operating spindle, wherein the handle can move between a locked position and an unlocked position, a hook mounted on the handle and secured in rotation therewith, wherein the hook has a throat in which a latching point of a structure is designed to engage when the handle is in the locked position. The locking system comprises a key associated with the hook and by means of which it is possible to pass from the locked position to the unlocked position of the handle, wherein the key can be removed when the handle is in the locked position and cannot be removed when the handle is in the unlocked position.