Abstract: An aircraft lighting system is disclosed in which conventional visible light sources at the exterior of an aircraft are provided with optical filters which block infra red light. In this way, it is made possible to use visible external lighting (required by Civil Aviation Authority regulations) during training exercises involving infra red sensitive night vision goggles, which would otherwise be dazzled by the infra red output of the visible lighting. Also disclosed are means of selectively controlling both visible and I.R. light sources using a single existing cable.

Abstract: An adjustable electrical device, such as a trimmer capacitor, comprising a housing and an electrode movable relative to the housing, the electrode comprising a screw-threaded portion which is resiliently deformable to allow compliant threaded engagement with a complementarily screw-threaded portion of the housing of slightly smaller diameter. The screw-threaded portion is split to allow said deformation, the split being in the form of a slot extending across the screw-threaded portion, parallel to the rotational axis of the screw-threaded portion. A further slot is located at the base of the screw-threaded portion, which interconnects with the slot. The electrode is provided with an actuating member having a head portion adapted to receive an adjusting tool, such as a screwdriver, and a body portion which is an interference fit within the electrode.