a fastening device for fastening a movable element to a structure includes a support member and at least one belt retractor having a retractable belt and a fitting . the belt retractor may be fastened to a support member . the belt retractor is arranged in such a way that , if the fitting couples the structure and the movable element , the retractor prevents unrolling of the belt by more than a predefinable range if an external force , such as sudden mid - air turbulence acts on the movable element . thus , the movable element is secured .