Transparency having sensors

A system for preventing overheating of a heating arrangement of an aerospace transparency, the transparency mounted in opening in body of an aerospace vehicle, the system comprising:

• the transparency comprising a plurality of glass and/or plastic sheets joined together to provide a laminated transparency, wherein one of the sheets of the plurality of sheets is a glass sheet heated by the heating arrangement, wherein the heating arrangement comprises an electrically conductive member, positioned over a major surface of the glass sheet and a pair of spaced bus bars electrically connected to the conductive member;
• an electrical power source having a first terminal connected to one of the bus bars by a first wire and a second terminal connected to the other bus bar by a second wire;
• a switch electrically connected to one of the first and second wires, wherein the switch in a closed position passes current between the power source and the bus bar, and in an open position prevents current from passing between the power source and the bus bar, and
• a controller connected to the switch and connected to one of the wires, wherein the controller measures the resistance of the bus bars, and when the measured resistance exceeds a predetermined level, the controller acts on the switch to place the switch in the open position.