A method for operating a wind turbine is provided. The wind turbine includes a rotor including at least one rotor blade and a pitch drive system coupled to the at least one rotor blade. The pitch drive system is adapted for pitching the rotor blade. The method includes: determining an actual value of a first variable indicative of an overspeed state of the wind turbine; determining an actual value of a second variable of the wind turbine correlated to the rate of change over time of the first variable; and, estimating an occurrence of an overspeed state of the wind turbine from at least the determined actual values of the first and second variables. The pitch drive system pitches the rotor blade for aerodynamically braking the rotor based on the result of the estimation.