In a method for the control and protection of a gas turbine a gas turbine performance and lifetime indicative process quantity is estimated from a set of available process signals. The gas turbine performance and lifetime indicative process quantity is simultaneously evaluated by two different estimation methods, whereby a first estimation method has a high prediction accuracy, and a second estimation method has a high availability, a continuous adaptation of the second estimation method is conducted in order to align the output signals of the two estimation methods, and in case of a failure detected in the supervision of the first estimation method the adaptation of the second estimation method is stopped, and the output of the first estimation method is switched to the output of the second estimation method.