Compressor rotor blade flutter evolution is under study. The blade oscillation record spectrum is obtained by the segmented Prony method. As shown, the classic Prony method autoregression can be used by itself to identify the blade unstable oscillation regimes in the switching Kalman filter model. The unstable oscillation regime switching is similar to obtained by the segmented Prony method, but the regime switching estimate is less cost from computations point of view.