Attitude estimation of a simulated flight and GPS positioning with Kalman filter The Kalman filter is an algorithm used for data estimation and sensor fusion. It has been used for decades in several projects, especially in the aerospace industry, being the Apollo program for lunar explorations one of the first to apply the filter. As a way to analyze the practical Kalman filter application in real situations, this paper shows its use in the estimation of the horizontal attitude for an aircraft flight. The experiments were produced inside the X-Plane simulator, through its plugin system and with the estimation of data gathered from the simulated gyroscope. Additionally, a mobile application was developed to show the Kalman filter output for GPS positioning estimation under uncertainty conditions – in this case, inside a building. Results show the data obtained by the filter and a comparison of the values before and after its application.