An ice protection system for a structure having at least one surface to be protected from a range of icing conditions. The ice protection system includes at least one heater device, arranged in thermal contact with at least one surface to be protected; at least one temperature sensor for outputting at least one temperature signal, the sensor being in thermal contact with the heater device; and a control system for controlling the heat output of the heater device using the temperature signal. The control system is operable to control the heat output of the heater device in order to maintain the temperature of the heater device at a substantially constant temperature.