Abstract: A spooled optical fibre data transmission line arrangement, for providing communication between a missile and a missile launcher, comprising a rigid, fluid-tight, hollow body having first and second separable parts, the optical fibre being carried by one part and connected at one end via an opto-electric transducer to a terminal extending through the wall of that one part, and the other end of the fiber being connected via a second opto-electric transducer to a terminal extending through the wall of the other part. The two separable parts suitably meet at a tear line and tags extend from adjacent the tear line on one part to the other part ot assist in complete rupture along the tear line when the fibre is required to be extended.

Abstract: An aircraft attitude display device comprising: a circular array of radially extending selectively activatable display elements (5), the radially inner ends of which constitute a boundary defining a central space; within the said central space, a fixed aircraft symbol (7); and means for selectively activating the said display elements in accordance with aircraft attitude so that the selected display elements form a visible pattern, e.g. a sector of the array, bearing a geometrical relationship with respect to the aircraft symbol indicative of the aircraft attitude.The device is suitable for implementation using liquid crystal display technology to give a stand-by display of aircraft pitch and roll which is readily understandable by pilots since it is similar to the display given by conventional rolling ball action aircraft attitude instruments.