Abstract: This invention relates to an improvement in a flow sonde, particularly for measuring aerodynamic values in aircraft such as the total pressure, the static pressure and the total temperature. The improvement comprises thermally controlled resistor means in the sonde body, said means having a low increase of resistance within a specific temperature range and a high increase of resistance in an adjacent range, whereby there is obtained a high heating power at a low ambient temperature and a limitation of the power absorption when a predetermined temperature is reached.