A system for and method of indicating an angle of attack of an aircraft is provided. The system utilizes measurements from existing aircraft sensors so that a dedicated angle of attack sensor is not required. The system enables and benefits from a unique method that includes performing standard flight operations during a calibration flight. The system does not need any aerodynamic model of the aircraft because it utilizes information from the calibration flight to develop an estimated aerodynamic model of the specific airplane. The system utilizes the aerodynamic model and other information to estimate an angle of attack of the aircraft during flight. Finally, the system utilizes additional information to indicate the estimated angle of attack of the aircraft relative to an optimum angle of attack for the aircraft and/or a critical angle of attack of the aircraft. The system further enables recalibration, so as to accommodate aircraft aerodynamic modifications.