Abstract: An ice-protection system has first and second zones of a leading edge of an aerodynamic or streamlined aerodynamic component, each zone having a de-icing apparatus and an ice-detection sensor positioned behind an elongated convex window as to be aero-conformal with the leading edge. The ice-detection sensor is in the form of a module and has a sensor head having a front face and abutments at ends of the window. The ice-detection sensors may have a central light emitter and a plurality of sensor elements peripheral to the light emitter. The ice-protection system also has a control system responsive to the ice-detection sensors to control the respective de-icing apparatus, and may activate automatically a sequence of operation.

Abstract: An ice-protection system suitable for use in an aircraft comprises first de-icing apparatus operable to de-ice a first zone; a first ice-detection sensor positioned in the first zone and arranged to detect ice accreted on the first zone; and a control system responsive to the first ice-detection sensor and arranged to control the operation of the first de-icing apparatus.

Abstract: Ice detection apparatus for monitoring ice accretion on aircraft surfaces, comprising an array of optical fibres which are mounted flush with an outer surface of an aircraft skin, and an intermediately located electromagnetic radiation emitter which is provided by an optical fibre. In use radiation is emitted by the emitter generally outwardly of the aircraft surface, and the layer of accreted ice diffuses the emitted radiation scattered and reflected. The diffused radiation is detected by the sensors, and the spatial distribution of the detected intensity diffused radiation about the emitter can be used to calculate the thickness of the layer of ice and the type of ice.