The systems of tracking temperature in an aircraft are composed of outside temperature thermometers and engine temperature thermometers. Resistance thermometers are the most common outside temperature thermometers, while most common engine thermometer is a thermocouple. The aircraft Pilatus PC-9 (M) is equipped with several temperature tracking systems. The outside air temperature sensor is a resistence thermometer situated on the right wing of the craft, while the engine thermometers are composed of a parallel connected “K-type” thermocouples. Both of the systems are crucial for operating temperature regulation and due to the specific wear of the material and similar parameters like change of pressure, there is a risk od loss of function or any other possible malfunction. Therefore, it’s necessary to regulary perform a test of functionallity exposing the sensor to ice and observe as the temperature drops for approximately two minutes. If it works properly, the temperature will decrease logarithmically. As the temperature drops below +4 °C an indicator should activate as a warning to the pilot of the need for appropriate adjustments. Such a practical procedure was carried out in this paper.