Abstract: An aircraft cockpit canopy has a separable portion which is capable of being separated from a remaining portion of the canopy at a clearly defined break line by means of detonating cord, to facilitate ejection of a crew member along a predetermined path through the canopy, the separable portion being of such a size that hinges are provided to constrain it to swing in a predetermined path to clear the ejection path, the hinges being attached to the canopy and bridging the break line so that prior to separation, they remain unused but subsequently they are effective to pivotally constrain the separated portion. Conveniently, the separable portion may be in two or three large parts.